Testing some 303 British duplex loads Black Powder 303 British MORE POWER! • Black Powder 303 Briti... Black Powder 303 British • Black Powder 303 British
Major Ned Roberts' book "The Schuetzen Rifle" talks extensively about duplex loads, I highly recommend it to anyone interested in the subject. The purpose wasn't to increase velocity, it was to use the smokeless to blow the bp fouling out of the barrel, and when used in reverse (bp under a load of smokeless) it was to help ignite smokeless charges back when primers were inferior and inconsistent. I have an Ideal No. 6 powder measurer that is double chambered specifically for dropping duplex loads. The smokeless chamber is smaller than the BP side.
I figured as much. When the smokeless stuff is mixed appropriately with black powder I figured the increased chamber pressure and heat would force a cleaner, more intense burn and "atomize" the fouling into more smoke, effectively forcing the fouling out of the barrel and keeping things cleaner.
I tried it in my martinis about 5 years ago, got some bertram brass. I think I used 5 grains of bullseye and 85 grains of 1.5f. It was cleaner and more consistent in the 20 rounds I loaded up. I chickened out, did some 35 grain trail boss loads (very unsatisfying thoop), some buffalo rifle (5744) then went back to all black and magtech brass.
Interesting info! Thanks for that, willardspicer. I've never done a duplex load in my life. However, the preacher who I grew up with was a WWII vet who served on a battleship. He told me of smokeless powder charges in there big guns with black powder basically as priming powder.
100 years ago, was the age of the craftsmen. They could build anything out of nothing by hand, and make it work. Much had better specs than stuff typically made today using machines. Progressive depth rifling, for one example... Aircraft out of plywood and glue, for another example. Canning and food preservation methods for another. It is REALLY interesting, to get info on their techniques.... Thanks for the excellent info !!!
People look down on the technology of the past because people could "do it for themselves" and we have high tech machines that do it for us or do it better, but those same sneering people cant match the past. Today people cant "do it for themselves" like those in the past.
Some thoughts on duplex: 1. Useful technique for emergency use of BP in modern rifles (while stretching the supply of on hand smokeless.) Cleaner burning, albeit lower velocity. However, loaded rounds should be used within a short duration since long term stability of propellant may be compromised. 2. It seems the "model" is like "one-and-a-half stage" propulsion. The primer ignites the compressed smokeless first with rapid burn, pushing both the BP charge and bullet out of the chamber. The initial pressure pulse is much higher. The BP ignites while the bullet is still in the barrel, but only partially completes combustion before the bullet leaves the barrel. This results in lower bullet velocity for a given charge. As a plus, the expanding gas from the smokeless acts along the entire length of the barrel and blows most unburned BP and Burned BP residue clear of the cartridge case and the barrel. It might be possible to achieve the same chrono while reducing the BP charge somewhat since only a fraction of the BP charge actually acts on the bullet. This may need a filler to prevent powder migration. 3. Try shooting duplex with video under dark conditions to see if you can see how much powder burns outside the barrel ... 4. One solution might be to premix equal parts of BP and smokeless for the intial fill (determined by smokeless fraction), then top with remaining BP (reduced charge), then filler, then bullet.
I can't say how much without doing some math but at the very least removing the sulfur will lighten the molecular weight of the exhaust gasses; lighter gasses means higher gas velocity and should in turn result in higher projectile velocity for the same mass of powder.
You nailed it here. Took the words out of my "physics freak" mouth. This is exactly what is happening. The black powder is definitely getting launched out and burned outside of the barrel. Making a more homogeneous mix even just at the base will result in a less wasteful but slightly dirtier load.
Ive went from 0 interest in BP to looking into it hard and looking at getting some stuff. Only BP channel on the web i found thats fun to watch and can watch a full video without being bored.
A few years ago, I was trying to shoot an old muzzleloader that was too old to be taken apart. The only way we could get it to fire was to load 2 gr of FFF and the full load of FF. The nipple was nearly completely clogged. This solution came from the collaboration of an engineer/gunsmith and an older gunsmith. This was the only solution that worked on that gun. I mentioned this on RU-vid and someone that read the manual jumped on me like I was an idiot. I am the engineer/gunsmith! The only way to shut him up was to ask for his college degree in engineering or his gunsmith license. If you need to shut up, a moron, ask for something he doesn't have. The funny thing is he appeared to still be in the know-it-all years, pre-forties. Duplex loads have been used in so many guns since the beginning of guns. It wasn't until the early 1900's that changed. But if you think about it, the primer is a fast burning "powder". Even a cannon used a duplex powder load with a fuse. The 303 is not going to get too hot, unless you grind up the powder or use FFFF. Also, as your barrel gets fouled, the bullet will require more pressure to escape the barrel. Meaning the velocity should pick up the more you fire the gun, without cleaning.
Lyman made a powder measure, the Ideal NO. 6, with large and small reservoirs and two adjustable measuring chambers for dropping duplex charges. This technique was also used with some of the very early semi-smokeless & bulk smoke-less powders that were difficult to ignite by dropping a small primer charge of black under the main charge of smokeless.
Man you are wild. Easily my new favorite black powder RU-vidr. You actually try new stuff and experiment. I’d love to see a new how to series on antique muzzleloading propellant. For “educational purposes only” of course.
OH damn, where to start, I played with duplex loads for a couple years when I had my own range back in the early 90's. Had a lot of fun with it. DON'T try it if you have any doubts. My neighbor was into black powder for his .54 caliber muzzle loader and he was experimenting with duplex loads in it while i was doing 38-55 in an old Winchester something. We had a blast with them, literally, never blew anything up just loud bangs and lots of smoke. But it made clean up super easy in the muzzle loader and the Winchester. Our bottom load was Unique under whatever black we had on hand. No chronograph available to the public yet so we relied on targets at different ranges, out to 250 yards. Some went every where, others were used for hunting , plinking is what we did so forget that. Others around us got involved in this with their firearms and it went from their, it is really doubtful one of these loads will blow you up, but don't try it till you do a lot of reading and tons of light load experiments. The smokeless can be whatever you want to light off the BP but keep the volume down on the smokeless. There are a couple books written by gunsmiths who experimented with smokeless duplex loads, one of them was doing forward ignition and duplex smokeless, tried that to, very time consuming and way different than any other handloading. Gave that up after a few thousand rounds. Great video Jake, brought back some memories.
I used unique also, very little clean up. The forward ignition, like on some Cannon cartridges, Elmer Keith did with a small brass tube, duplex loading when he worked at the Arsenal
When I got into shooting BPCR in the early 1990;s, I used 3gr Rl 7 topped off with 65 grs of 3fffg under a 405 gr bullet lubed with SPG. Between the powder and the slug was a thin waxed paper wad, with a thin cake of SPG lube. This combination of the duplex load and the SPG lube, made it possible to shoot 50 rounds of 45/70 black powder loads, with no cleaning in between and superb accuracy. I later switched to magnum rifle primers with about the same results, without the RL 7. Keep up the good work.
Sounds on par with my experiences. I solely load duplex as it, with appropriate load development, lets me go to the range 100-200 rounds in hand and it´s downright RARE that i even have to clean between shots. At all. But, as noted it is very much a judgement call. Where i live it´s the old originals that are used and seeing that and duplex.. well. Fact is the oldest gun i´ve tried it in is the French Mle 1866 Chassepot. What is, basically, a 45-90. I normally use "the 2.8 factor". Ie; for whatever weight smokeless i add i multiply that with 2.8 to get a "blackpowder factor" out of it, and it works rather well. On the other hand, got me an 1886 Kropatschek and that thing sees nothing but duplex.
My dad had specific duplex loads he used regularly in his cowboy stuff. No holes were punched through time and space. The problem typically lies with that guy that lives by the "If a little is good, a lot MUST be better!!!". That's when there's bits of steel and fingers whizzing through the air. Anyway, that was really interesting. I couldn't even begin to tell you why it went the way it did, but it was interesting. And I would have to agree with you on why it burned so clean. Mostly because your conclusion made perfect sense, but also because I sure as heck don't have a better reason.
Well he said it’s not any faster but it appears the fouling gets burned off. I wonder if the jacketed bullets might be scrubbing fouling out anyway. I don’t shoot a lot of BP in cartridges and when I do I tend to use cast bullets. I’m not commenting negatively about this experiment I’m just saying why my conjecture is of the position it is. I have been Messi b around with BP slugs, making sabots from foam and using Lee REAL for 50 cal muzzleloaders. So far just strapping to the bench and shooting. So far no damage. I have a 20ga from a company with nonexistent product support that imports Turkish shotguns and uses the name of a small town in TX and they shipped a barrel with a deformity so I am limited in what can be done with it. Thinking BP 3” loads and push shot payload up until I burst it or can’t fit anymore shot in it. Maybe work up a BP buckshot load for it.
I feel your pain on asking certain questions. My kids bought me some 777 and some Pyrex for Christmas. They just don't fire in my old flintlock. SO, I asked about compound loading. Just 10 grains of real powder down first then 60 grains of 777 or Pyrex. You would think I called them dirty names and insulted their mothers. So I decided to do what I needed to do. It works, the gun fires every time and its accurate.
If you are shooting a flintlock and real black is hard to get. Then you've got to do, what you've got to do. Don't let the pursuit of perfection get in the way of the good is what I say.
I have shot hundreds of duplex rounds. We all did in local or club BPCRS matches in the early days and were limited to 10-15% of the bp charge. The NRA sanctioned matches were limited to straight black powder or Pyrodex. We appreciated the MV boost but the main reason was to decrease fouling. My go-to duplex powder was IMR 4227. The thought at the time was each grain by wt of smokeless was equal to about 7 grs BP. I had no problem with it. When you got the lower MV results I noticed several "contrails" of ejected particles still burning. I wonder if that load just was not completely burning in the barrel?
@@Everythingblackpowder Back in the 70's a bunch of us used to initiate newbies that wanted to shoot our personal black powder rifles, we would load a heavy load and let them shoot it. That pretty much stopped them from asking to shoot another man's rifle. But it also showed how much powder was getting burnt after exiting the muzzle. Often there would be a flash 3 to 5 feet long into the great wide open, especially if it was dark out. Try shooting your lower MV loads into the ground after dark, you might be surprised at the powder you are burning outside the barrel.
I have a Lyman black powder guide from the early 1970's and the Lyman guide mentioned duplex loads used by shooters competing in long range matches such as the Creedmoor BP matches. The Lyman guide however did not reveal any load data. So don't listen to the naysayers...The Lyman guide was printed before most of them were born.
Modern artillery uses duplex loads because even though pressure is less in black powder the flame jump speed from grain to grain is faster. I believe there is a central column of black powder surrounded by smokeless for the charge. This carries the primers flame throughout the powder load faster and creates more pressure. Our military is largest customer for Goex and therefor dictates the specs for the burn rate we see.
I was thinking along those same lines. The BP is easier to ignite and is on the primer side and carries a hotter flame to the smokeless powder in those cannon rounds.
Well. There are three kinds of people. Chefs, who can take any combination of foods and make you a meal. Cooks who can follow a recipe and make a decent meal. And people who basically are so inept that they need to just stick with eating cold beans out of the can. Virtually every naval rifle and most artillery use a duplex load of sorts. It’s nothing new. Every 30 pound bag of powder for a 16 inch rifle has a patch sewn to the base containing about 5 pounds of powder. This as an “initiator” for the main charge. The naval ballistic engineers that made up these loads are chefs, not cooks. What your doing in making duplex loads is I think not an attempt to initiate your main charge, but to boost it. In terms of performance. And you are intuitively correct. Your trading a bit of fast-low energy volume for some slower-high energy volume. Think in terms of volume equivalence of potential energy. Obviously I have done this. With smokeless propellents. That’s where the true danger lies. Your still on relatively safe ground. Trading volumes between two relatively safe alternatives. Simply never exceed the max load of smokeless. Black powder will always “dilute” the power of the smokeless. In general terms. Your experimental approach is sound. Even interesting. I’ve not really thought much about this in 40 years. As you progress from cook to chef you must expect a certain amount of noise from those poor souls relegated to eating cold beans from the can. Such is human nature. Fox out
I have tried it in double rifle calibres using 5744 in an attempt to get the velocity up to regulate, the smokeless needs to be on the primer, but all I found was that it burned very much cleaner. Many thanks for posting this information. Chris B.
Excellent work, I knew you had it in you! I always found those Fudds online in the forums to be ridiculous talking about how guns magically get turned into pipe bombs whenever yadda-yadda-yadda blah-blah-blah. I am a physics nut so I have known for a long time that there is a right and a wrong way to do something like this and that when done correctly it is safe to work with. Good on you.
Elmer Keith (and others) experimented with duplex loads with smokeless powders of different burn rates - one fast and one slow. Their concensus at the time was that it wasn't worth the risks because the hoped for gain didn't happen. I did think, (one time) that maybe the smokeless powder was pushing the black down the barrel. With one of the shots, it looked like a couple puffs of smoke occurred down and right of the main cloud - as if some grains were igniting in the air rather than burning in the barrel. Might be worth using same ratios, but mixing the smokeless throughout the black to see if that makes any difference. Good video.👍
Interesting, i was guessing that maybe the smokeless finished expanding before the bullet left the barrel leading to temporary faster acceleration but not that reduces the efficiency of the black powder because it has too much space or not enough time to push the bullet
Thanks for the video Jake. We have been using the duplex load in our Rolling Blocks, Hi Walls & Sharps rifles for years. 3-5% smokeless under 2Fg BP in 40-65, 45-70, 45-90 & 45-110. The error spread is more then straight BP but with the duplex load blow tubing not necessary. Cheers
There is a line between "don't do it" and "be careful', and if you don't know how to do what someone is asking about, please just refrain from giving your thoughts on it instead of proclaiming it to be impossible. Great video and all who watched it are more knowledgeable than before!
I recall an American Rifleman article from maybe late 90’s that described people mixing fast and slow smokeless rifle powder to flatten and square up the pressure curves.
Yep, i have made and fired many hundreds of duplex loads with a fast smokeless powder igniting very cheap 50 cal powder. Very safe and low pressure. But really really cheap. 30-06 works great. Even worked in 454 Casull. It's a cheapskate method because i bought 8lb kegs of 50 cal powder for 36 bucks. ;-) (Don't ever do it, though)
first exposure to duplex loads was .45-70 in a Gatling gun! WIN296 and FFFG, been 30 years so the weights escape me, we'd handload in single stage rockchuckers all week for hours after work..... then have the best 2 hours of fun you can have with your clothes on!
For special applications, duplex (or more) loads are used in a lot of Military impulse cartridges. They are designed to reach a specific pressure volume or peak pressure at a certain time. These are used in anything from bomb racks to ejection seats to EOD power actuated tools.
Here are two cents. In this comment I am speaking exclusively about black powder and smokeless powder as it pertains to cartridge firearm loads and the shooting of such. If I recall correctly, everything I have read in all of Paul Matthews’s published works I found nothing talking about dramatic velocity improvements. Paul Matthews said, the primary purpose of duplex loads was to reduce the amount of fouling when shooting black powder cartridge firearms. Paul Matthews left us a wealth of knowledge. My only purpose in using a “dash” of smokeless is to reduce fouling in the bore and the mechanism of a given firearm. For me It serves this purpose alone. So, I only use just enough to effectively clean out the fouling, and not a “dash” more. Thank you Jake for courageously casting little light onto this topic.
Your assessment is correct, in that particular cartridge you are simply trading ratios between two different gas makers. RX-7 is an excellent booster for duplex loads because it has been a very high-nitro double-based powder since the late 80s and thus lights very well and burns very well at low pressures compared to many extruded rifle powders. However, in the small 303 with a bottleneck and small bore, the only way to get more velocity is to increase pressure up into the normal operating range for the cartridge with a propellant that has a long enough burn curve to push past what black powder is doing. RX-7 by itself is a superb choice for the .303. Duplexing really shines when you get into the super-squirrely zone with all-smokeless. Using a few grains of I-4198 to kick off a full case of .50 BMG or 20mm surplus powder can be done very effectively in bottlenecked, high-pressure cartridges and rifles where a case full of the cannon powder is safe in the first place, then start substituting in a little kicker at a time until the burn cleans up and the velocity begins to come up to what you would expect as normal for cartridge and bullet combinations and powders from the manuals. Duplexing smokeless can and will easily kill you and your friends if you're stupid about it, but that should go without saying, but there are ways to research and experiment safely if you understand what you're working with.
Great stuff. I have also done plenty of smokeless duplex loads, using a fast smokeless powder in front of 50 cal smokeless powder. Works great and perfectly safe in ammo from 308 and up. 30-06 works really well. Very cheap. Don't anyone else ever ever try it, though.... ;-)
I have been shooting duplex loads in old and new Sharps rifles since the 1960s. In the 1960s the only reason to do it that I was aware of was to shoot cleaner loads and produce higher scores. Chronographs didn't exist for the average Joe and it would have been a bit of work to calculate velocity. By my opinion duplex loads have always been about shooting cleaner loads and reducing BP fouling. Good video, I bet a lot of younger shooter never heard of this.
I don't know why, but this video brings back memories of a guy around here, when I was younger, who loved muzzleloaders, but couldn't always get black powder. He had a Lyman Plainsman Rifle, or something like that. Anyway, he made a special powder measure that he used for Smokeless powder loads. (Yes, I know that loading a modern black powder firearm with even one grain of H4895 will cause a crack in the space time continuum.) He maintained that it was safe, as long as you paid attention to the details. But he also said that he would not recommend any of us try it. I always wonder though, if he just liked experimenting, and the "can't get the real stuff" was just an excuse.
The results were much less speed than i could imagine from those duplex "alchemist" loads, very strange how clean it burns than pure BP. Really the best videos!
Thank you for doing this. Topics like this I think are good to show because it sounds scary to people who don’t want to learn anything or think for themselves and just follow directions. And learning is the only way to keep our recreation going.
Love the video. I played around years ago with a NEF handi-rifle with a 20ga ultra slug barrel: a heavy barrel made from 12ga barrel blank. I shot some duplex loads out of that but using Re7 and 5577 and you brought back some fond memories.
In soviet union there was a problem with reloading components, existed primers didn't work well in a cold weather. So hunters used so called "winter loads" for shotguns. They put small amount of black powder on the bottom of the shell and main smokeless load above. When Berdan style primers were used, it was recommended to put a few grains of black powder into the primer pocket
Many years ago I played with using 5 percent Red Dot under goex FF in a 43 Spanish Remington. The reason was to make shooting cleaner. My way of loading and shooting I could only see a little cleaner. So I stopped and went back to straight BP. Thanks for your effort. Good video.
I put together some grandson loads for my 303 years ago. I used 100 grain .312 bullets I had on hand for my revolver. Enough Red Dot to hit 1600 that I found in an old manual. He had to single load them, but for a 12 year old it was a great load.
Excellent video. I would have started the monolog portion sporting an eye patch just for the hell of it. The comment section has lots of real good information on past use of duplex loads. Even though I see no value in duplex loads in my life, I enjoyed the content. Keep up the excellent work. And don't shoot your eye out kid.
I’ve thought about this topic from view point of blasting logs. I have an old unknown tin of shotgun powder that I thought of using as a ‘duplex’ load. My gut feeling was to put the smokeless at the end of the burn rather than the start because obviously, the more pressure, the faster the decomposition. So in my instance, the black has built the pressure and heat before the nitro even starts. Never tried it and it’s hard to collect scientific data when splitting logs. But your work is certainly thought provoking
I will have try and find my notes from when I was loading duplex in 45-70 for BPCR 20 years ago in my rolling block. I remember it wasn't alot of smokeless, I did it for the cleaner burning so I could shoot more before I had to run a borepig down the barrel.
in fireworks, people send shells up with BP. They send rockets up with BP or Rocket Candy (Saltpeter/Sugar). In TM 21-210 (S1#9) Pickatinny Arsenal states that a granulated fudge-prepared Rocket Candy mix (3:1wt) functions as small arms propellant, with exemption of pistols (i presume for cycling reasons, like can happen with bp). I would love it if you as an outlier would prepare US Army improvised White Propellant as per 1969 instructions and tested it in your standard way in a BP rifle and revolver in the usual way. You tried sulfurless and sodium powder with interesting results, it would be extremely watchable to see by how much basically "rocket candy propellant" would undershoot your creations and the benchmarks Goex and triple7. It will not be a winner (or will it?) but by how much? How gummy would it get? (sulfur is way harsher on steel than any carbohydrate so its safe) How many fps? The fairly large amateur rocketry community too would find it interesting how their powder performs in a rifle. Did Uncle Sam send people into war with a recipe for sneezing powder or did their improvised powder do the job, and how well? This oldtimer, and many with me, wants to know!
Triplex, another type of duplex, and black powder competition. Dick Cassul, the biological daddy of the .454 revolver cartridge that bears his name, used loads consisting of three powders in his testing, mostly before the cartridge went commercial. My faulty memory, going back to things I read in the 70s, and 80s, tells me that he used a small charge of Bullseye next to the primer, the largest charge of 2400 (and maybe some other slow pistol powders) in the middle, topped by Unique, in a larger amount than Bullseye. Do your own research ti verify. Another 'duplex load' as descriibed by Rocky Gibbs the designer of Gibbs wildcats, used a single smokless powder per case, though he experimented with more than one powder. What he called a duplex load, once again from memory, used a primer or flash tube, that carried the flash closer to the bullet base . He experimented with different lengths, widths and materials to make the tubes. He claimed more velocity (inspite of less case capacity, a cooler barrel, and less throat errosion, since the flame front went from the mouth of the case, pushing unburned powder toward the base where it was trapped. At least to a greqter degree than normal. Also in early twentieth century black powder matches, a very small amount of smokeless was the first charge, followed by the prefered black gun powder. the smokeless was fast, like Unique or even Bullseye. As more of a primer than a propellant. The purpose being consistant ignition. They also spoke of greater cleanllness. I can't recall if these matches were muzzle loading or cartridge, but they were black powder matches, and adding smokeless, quickly became cheating. Some shooters still did it, and had to find ways to conseal their crime. Just like car racing, isn't it!
I experimented with duplex loads 40 years or so ago shooting 45-90 out of my Sharps. It was strictly in an attempt to reduce fouling. I can't remember the particulars though and my notes were lost somewhere along the way during a move. All I can say for certain is that I went back to loading straight black. I enjoyed the hell out of this video. Nice job! 👍👍!!!
Very educational . I too have dabbled in the alternative propellants etc . One to try is gun cotton . Tried it in 45/70 gov sharps rifle and it worked very well . Started low and worked up . Clean burn and good velocities . Tried it in 44/40 single action army and I wasn’t impressed . Good fun though 👍
I've done some duplex smokeless loads for my .45-120(a slower smokeless and a fast smokeless) - both ways. Fast over slow, and slow over fast. Key is to start low on both, and work up. Both having a 5%-10% fast, 90%-95% slow - just different positions in the case.
Its my understanding that duplex loads were somewhat popular in the late 1800s and early 1900s. Right when smokeless powder was coming out. I understand a small amount of black powder was sometimes used to help give better ignition for early smokless powder that sometimes did not combust fully. ... personally, i dont see nor have a need for duplex loads. As always, i liked and enjoyed the video. Keep up the good work!
Gawd I know Jake!!! My own father in law...died in 1993 age 90), did that... He used to load 45/70s with black and some smokeless plus creamed Wheat as filler. I pulled a few bullets and measured it. I NEVER FIRED ONE in the guns I have in the caliber. I have zero Idea what smokeless he used. I know, older guys had long experience with what they do. I STILL don't trust it. You sir are a.. I don't know if better, but braver man then I. btw 303 Brit. Lee-Metford was in black.
Food for thought. Take a smokeless muzzleloader and duplex a Swiss 3-fg load, or anything that is actually available that might possibly equal a Blackhorn 209 load since 209 is virtually non-existant.
I saw a duplex load in a shotgun shell once which kind of surprised me, half of it was flake powder the other half was extruded tube powder, both smokeless.
Interesting results. Back in the late 90s my dad and I tried a few duplex loads in a 45-70 Perdersoli Sharps. I don't remember much about the load specifications but I think it was around 10ish grains of smokeless and 65-68 grains of 2f. I remember that we got better velocity than straight black but stopped using the load due to safety concerns. We did place fairly well in a couple 1000 yard gonge matches though.
When running low on both black powder (which can happen these days) and Pyrodex I load 20 grains of BP first in my flint lock ML and then 60 grains of Pyrodex on top of that with a single projectile. I load this at my work bench the night before the hunt. In the field it's all black powder. The purpose is to just use up all my different powder types together.
It’s all about common sense Jake. That’s why there are Darwin Awards because of a lack of sense. Kind Thanks for another interesting and informative vid! Many Blessings and Higher Velocities. DaveyJO in Pennsylvania
I went back and looked at the relative burn rate charts for the smokeless powder used. The Alliant Red Dot was ranked 9th fastest out of 175. The Accurate 5744 was ranked 71st fastest out of 175. The Alliant Reloader 7 was ranked 77th out of 175. So of the general population of reloading powders, these were all faster than the median (87 or 88). It might be worthwhile to try a slower powder like Hogdon H870 (ranked around 165 of 175). I picked that one cause it was on sale on Brownell's ... Also, I plotted total charge weight vs avg speed and given four points, you can drive a straight trendline thru all four error bars. I expect the red dot might not really be on that straight line cause it burns so much faster plus it had the smallest BP charge, making it the most efficient ... but it was the smallest in terms of total charge wt.
9 grains of green dot in my 8mm mauser with 205gr cast bullets is just subsonic. 13gr is the old famous "The load" and is my longer range plinking load. More than likely since these "DOT" powders burn so fast and create a lot of pressure early it gives the bp a small window to react. So the less smokeless load did better because the bp actually had time to contribute, while the more smokeless load was already way down the barrel before the bp burned. I feel like something like 3gr of red might be enough to do the cleaning effect and keep speeds up.
Not being a safety freak is one of my favorite things about this guy. I completely agree, if you try something stupid that's on you. I wish other people would be more willing to share their loads. It is is better to give someone a starting point and something to go by than it is to make them guess on their own and blow themselves up.
I have shot numerous loads duplex in a 303 Martini Enfiels 303. Duplex loads burn cleaner. For best accuracy, paper patch cast projectiles with 2 wraps of cigarette paper then size with bees wax . Accurate and lots of fun. You must paper patch with a few beers whilst doing this procedure. This step is essential. And size 2 thou over bore diameter. Copper projectiles need speed to perform accurately.
This is Shaun from rebels barn I make and shoot my own 4inch civil war style canons I learned to make powder from you the 75-15-10 method/willow my pucks do not dry in the swampy environment I live in so I bake them in a small pizza oven plastic bulb type at 325 degrees for 20 minutes pucks blister and turn to iron try this from what I can tell it's stronger than go-ex seems clean to me
My old Lyman reloading manual 46th edition shows 2 duplex loads for the 50-70 using SR4759, and also shows duplex loads for the 50-90 using the SR4759. It even has one duplex load for the 50-140. I tried the 50-70 duplex loads in a rolling block rifle that I had back in the 1980s, but the rifle had an oversize bore and would keyhole bullets with full loads, black powder only, or duplex. The duplex loads were certainly cleaner shooting.
Your topic reminds of the time I told an ex Marine and gunship owner of my intention to cut down 9X19 spent cases and re-size/form them to 9x18 for my Mak. He scolded me up and down, said don't do it that I blow the gun up and hurt myself. He was completely wrong, it worked out great. I use duplex loading sometimes to get stubborn propellants to ignite completely, i.e. 3-4 gr of BP in a Ruger Old Army with the rest being a BP substitute. Another example that worked is using 5gr of BP in 30-30 to ignite WC-866, a slow burning military pull down powder made for .5O BMG. A few grains of Trail Boss first in my Savage ML-10 will do wonders for setting off one of my benzoate based BP propellants. Lastly there has been research and patents issues for so called 'progressive propellants'- this is where you have 2 different particle sizes, finer and courser blend designed to sustain the pressure curve and create higher velocities via a plateau pressure curve rather than a spike/peak.
I've been using duplex loads in 30-30 and 45-70 for several years. You really don't get much of a performance boost with duplex loadings. I've noticed a slightly larger standard deviation than straight BP. Where the biggest benefit, especially in small bore (30-30) is the reduction in fouling. If you can swab after every few shots then probably no need to shoot duplex; but, if you want to maintain accuracy over a larger number of shots then you may find benefit. Working up loads for the best accuracy is a long and tedious process.
Some Soviet manuals for shotgun cartridge reloading with smokeless powder recommended adding a few grains of black powder to the bottom of the cartridge case. The reason was that the old-fashioned primers intended for black powder did not ignite smokeless powder properly
Interesting experiments. I do question the practical utility of creating loads that can change mv and poi by the simple act of shifting the relative positions of the bp and smokeless in the cartridge. Even with compressed loads, under field conditions it seems to be you would get some migration and mixing of the powders unless you could maintain a consistent orientation of the cartridges and avoid any sharp movements. I'd add, you may want to consider that the disappointing results of the mixtures had to do with the effect of both temperature and pressure on the mixed components. If your bp is burning at a lower temperature and pressure than a straight smokeless load, the effect might be to reduce the rate of combustion of the smokeless part of the load, resulting in lower muzzle velocities compared with 100% bp loads.
I remember reading a long, long time ago that Elmer Keith loaded an shot some duplex loads. I can't remember what he was shooting or in what. All I remember is that he did it. I would ask what you do with your cartridges after firing BP in them to clean them? I always learn something from your videos. Thank you very much. Keep up the great work.
