These are my thoughts on choosing a powder for 223 and 5.56 pistols and SBRs. Find me other places: ➤ / reloading ➤ / johnnysreloadingbench ➤www.subscribestar.com/reloading ➤paypal.me/jrbdonate Product links may be affiliate links.
Thanks for addressing this subject! There are tens of thousands of pistols and SBRs purchased in the last couple of years who may be interested in reloading. Please make this is a series.
A lot of Mk 262 rounds were fired through the 10.3 inch barrels of the Mk 18 and the original powder was reportedly Tac. That combo worked well, according to some folks. I might try something similar in my 11.5. Btw your Mk 262 clone series was the best set of RU-vid videos ever made. Thanks
With my 11-inch SBR upper, I've found that (26 grains) of Varget or CFE-223 with 55-grain X-Treme FMJ's work very well and give very good accuracy and function. As to load data for heavy bullets in .223 up to 90-grains, Richard Lee's Modern Reloading book "Revised 2017", or later publication date is one stop shopping for bullets/powders. This manual shows 77-grain Sierra over a starting weight for LT-30 at 16.5gr (2342 fps) to 18.3gr (2539 fps). and LT-32 at 17.9gr (2417) to 19.9gr (2625 fps). velocities are shown from 20-inch barrels. (edited) my inability the spell sometimes astounds me.
CFE-223 Runs AMAZING in my SBR and I am getting an average velocity of 2661 with 62 gr apeer gold dots. In my 18", same load only gets me 2867 avg. Very weird, but my SBR loves it, so its my new defense load.
@@siconic21 Yep, my 11" SBR it has an RJ of Texas three baffle Brake/Comp with 13/16 coarse threads at its rear for the provided Blast-Can (attenuator) that mitigates the muzzles flash/blast forward and away from the shooter (all my uppers have this 6.5 Grendel, 7.62x39). The other reason you've touched on. I can use the same load in either the SBR, or the16.5 inch .223 Wylde upper.
Using 26 grains of CFE223 and Hornady 75gr Match bullets in my 20" give me about 2900fps. Wicked fast but not better than 1 MOA. I'm about to try again with Win748 and H322 and drop the CFE down to 24 and work up looking for accuracy
@@chavezhead I haven't had much success with CFE223 unless the case is VERY full, and it still burns dirty. Not being temp stable complicates things, significantly, when trying to push the limit on max load. One day your good , the next you're blowing primers. For a 20" I would try Varget or N140. Load as long your magazine will let you (extruded power). Anywhere between 24.5 and 25gr seems to be about the limit of Varget for 77/75 depending on chamber. Velocity will not be screaming but the accuracy will surprise you.
I understand all the picking the best powder to fit the specific guns and bullets and primers arguments and it can give you maximum accuracy but that mostly mattters on specific shooting platforms such as competition and sometimes hunting. We have to face the facts of today and that is components are limited everywhere, increasing in price everywhere, and nonexistent in some areas of the country. So maybe a versatile powder that covers a range of calibers is an approach to take instead of many specific powders for every gun we own. Versatile powder to cover small rifle loads, versatile powder to cover magnum rifle loads, versatile powder to cover small pistol loads and versatile powder to cover large pistol and magnum loads. HP 38 is great for most pistol loads, accurate 2200 is great for many small rifle loads and so on and so forth. We are in a period of time that you better get what works and as much as possible in relation to availability and affordability. Primers, I had to drive two hours away to buy primers that cost nearly twelve bucks per leaf. So talk about things as business as usual just isn’t reality. Things are changing and quickly. Our feckless leaders nationally and locally in many places are trying their best to enact gun control. A purposeful campaign on limiting supplies to the general public and what we can get is atleast fifty percent higher than it was before 2020. When I started the reloading journey in 2008 I could get anything in two or three locations within fifteen minutes of my house. A set of 223 rcbs dies was under 25 bucks and a pound of powder could be purchased for under 20 bucks. Now powder averages 35 to 40 per pound and I have not bought a set of dies in five years. I never purchase new brass it’s just plum ludicrous. Yes, it has changed, all for the worst for you and me. So that is my suggestion and the reasoning behind it. Take it or leave it. God bless, and look far and hard, one day you won’t find it.
Thanks for the extensive look into this and so many other things that you help us with. Every time I think about looking for data on another project you're my first go to sorce because you aren't afraid to do the hard work in research, lol it's not easy but dang sure is fun.
3031 delivers the fastest speeds without flash in my 16.5 inch 308 barrel. Sierra’s old hunting load for 150 grain bullets was 43.6 ish grains. I worked up to it and found that it was running 100-150 faster than Varget, 4064 or 748. Tac was equally fast but was flashy.
Agreed. I'd joke with my Dad and told him I wouldn't want to shoot my .30-06 with 3031 because I might set all the desert grass and brush on fire. 🔥 LOL It really does have a significant flash because it lacked any flash suppressant coating based on my many years of using it for my very accurate hunting loads. Good Stuff that IMR 3031, Yessiree!! Thank you, JRB, for all your testing and presenting efforts. In all the decades I've been hunting (some 6 decades now) I've tried a few loads then settled on one powder and MY data to give me 3/8" 5-shot groups at 100 yards all day long. Or until the barrel said it needed a break. Point is, find what works for YOU and stick with it until it doesn't work any more then begin again.
you are so right on powder working in a sbr and not a rifle system . i loaded up 1000 for my old 11 1/2 in sbr yrs ago . worked great . fast forward to 6 mths ago figured i would shoot it up for the brass . shot it in my new 24 in bull barrel . it would cock the hammer but wouldn't pick up the next round out of the magazine ! but works great in my 16 in carbine system . the load was a 55 gr fmj using pmp brass and data powder . accurate sold it many yrs ago . was from pull downs . i got it back when accurate was still in mcCowan tn , yea that long ago ! you could walk in with a 5 gallon bucket and tell the owner you wanted 4 # of it and you would walk out with a 5 gallon bucket filled to the brim at the same price as 4 # !! oh the good ol days ! i still got around 14 # of it left lol ! good powder they post data for it still . my sbr loved a load just over starting so that is one resin my rifle system didn't work right . upped to a mid range load and rifle works great . keep up the good work johnny !
The silly car and cliff comparison actually helps a lot. I'm new to reloading and have been looking at the technical data as datasets only but that silly comparison just made so much sense and helped make it click!
For my 11” SBR, I spent a lot of time looking into projectiles that would give expansion at the longest range, and the 64gr Nosler BSB ended up being my choice. Ram TAC is my 1st choice, and CFE223 my 2nd. I seem to remember working out I could still get expansion at a little over 320yards. The Federal Fusion projectile was slightly better, but very hard to come by outside of factory loaded ammo. Another good option is the Barnes 70gr TSX to make a clone of the 5.56 Optimized “Brown Tip”. Barnes has 5.56 NATO Load data for 10,14,16 and 20” barrels which I really appreciate.
The 64 grain nosler bonded is my go to in 556 for defense and hunting. I settled on 26 grains of tac loaded to 556 pressures. Worked that out from ramshot data that gave a max of 26.3 with a 65 grain Sierra gameking. Close to 3000 FPS from a 16 inch barrel. I’d have to look but I’m pretty sure around 2750 from my 11.5. Super tough bullet that does well through barriers and expands well. Too bad it was discontinued but I still have about 500 and 300 loaded.
Very good idea for a new series, should spark lots of interest. I personally went down this rabbit hole when I got a 10.5”. I feel like anything shorter is a waste. There are also different goals to chase. Do you want low flash? Quiet? Fastest or most efficient? Most accurate, low SD? Reliable/cycle? Etc. what’s important to one not important to you. For me I just wanted reliable and low flash, I ended up going with H335 and 62gr fmj for playing, I had it on hand and It did fine for me. I didn’t try to stuff as much as I could in it like a bolt gun. I would probably just blow unburned powder out the end. Thank you for addressing this issue, looking forward to learning something
Thanks for doing this. I have a 7.5" barrel with a 1in 7 twist. Tried all the powder and bullets I had, being I haven't been able to buy much here in Washington State, found 3031 with a 60 to 70 grain bullets worked best in my barrel. I wanted to try a faster power, but not available here yet, to see if I could tighten up my groups. Can't wait to see what you get. Thanks.
QuickLOAD says for a 60 grain projectile, only 81% of the IMR 3031 will burn in a 7.5" barrel. It's up to about 88% with the 68 grain pill. VV N125 looks good, but no actual published data. Same for Nobel Vectan BA6½.
Thank you. About time someone developed a load for sbr's. Can't 2ait for the info, I knew if we played with powders and barrel length we could get something badass. With all of the shrt barreled 556'sout there and not 1 damn ammo company has come up with something badass for them, everything is developed and sold for fricking 16-24" barrels.
Very intriguing! I’m pretty new, the concept Is fun to explore! Can’t wait to see what you come up with! I’m looking to maximize velocity in 9mm for barrel lengths from 3.1”-5” and also mid length PCC barrels such as 8-10.5” I’ll certainly be taking notes on the topic/concept of powder selection! Thank you Johnny! You rock man!
I mostly just load 9mm for function but have a couple powders I use and Alliant Blue Dot is by far the highest velocities. I was getting 1400 fps with 115s out of a 5" barrel and under max powder charge.
Definitely a great idea for a video series. But for 556, anything south of 10.5 inches is just a range toy. I'd focus your energy there, a ballistic advantage modern 10.5 inch barrel is about 120 dollars, very high qualityfor the cost. A Rosco 10.5 is very similar. It would be great if you could shoot groups and chrono these loads. And as a final cherry , send the best of these loads for some ballistic gel testing to guys like BUFFMAN range. I'll definitely be tuning in to the rest of this series, if you pursue it.
I went through this process myself a while back and ended up choosing H322 and Vihtavuori N120 for my short barrel 223 and 300 blk loads. H322 works great for the heavier bullets, while N120 is especially useful for high velocity 110 gr bullets. Sadly, with how things are currently, what is actually available has to be a strong consideration as well. You might not be able to buy the optimum powder, so learning how to adapt load data safely to what components are available becomes more important.
My hypothesis is that for reasonable barrel lengths, what ever powder gives you the best velocity for longer barrels will be the better powder for simply velocity in shorter barrels. I imagine that the consistency may decrease with slow powders in short barrels and that you will have to deal with alot more blast and flash too. But, if I was a betting man, for simply velocity, the slower powders will be better. If it is worth the drawbacks mentioned earlier, that's a decision everyone has to make. I did a small sample size experiment with a 2.25 357, and for 158s h110 produced better velocities than the slower powders such as hs6 and accurate 7. It all has to do with area under the curve. A slower powder that gets to the same pressure as a fast powder, will have a higher overall pressure, doing more work onto the bullet. Even with slow powders in short barrels, you are well on the down hill side of that pressure curve by the time the bullet comes out of the barrel. I think your 300blk sub results are not exactly comparable because you are not running at maxish (technical term) pressure. I would love to see a test or even a little mini series on this. Love the content man.
^ This exactly. I was going to type up a longer response, but you pretty much nailed it. For max velocity, the amount of residual pressure at the muzzle or the % of supposedly unburned powder doesn't really matter. What matters is the area under the pressure curve acting on the bullet, the work done on the bullet. If you have a slower powder that creates a longer pressure curve than a faster powder, and they both have the same peak pressure and same general shape, the longer pressure curve should do more work on the bullet, regardless of whether there is a few % unburned powder at the end or not. 7.5" is pretty short, but in general I've usually seen the same loads that are fastest in my 18" barrel, deliver the best velocities in my 16" and 10.5". Of course this is all with powders that are well suited to and commonly used in the case. I would guess that the Hornady's SBR specific loads are more focused on controlling port pressure in short gas systems and flash suppression than maxing velocity and power in short barrels. I'd propose an easy but interesting test, load up a couple spreads each of several normal .223 powders that run the gamut from the slow end of that particular case/projectile combo to fast end, and run the spreads in both a longer barrel and a short barrel. Either turn the gas systems off or tune both ahead of time and see what powders give you max velocity before hitting pressure. The pistol length gas system may run better with the lower port pressure from faster powders (or maybe not) but I'd bet the same general powders will give you max velocity in both. You could also try the test with heavy bullets and light bullets, IME though, heavy bullets usually lose proportionately less velocity as you go to shorter barrels, than lighter bullets.
I would love to see a reloading adventure for SBR/ pistol .223 using CFE BLK and AA1680. I would even be willing to send a lb of each to donate to the cause! Your patreon is probably the best money I spend each month. :)
If you look around Barnes has some load data that makes a good starting point. The data is limited to just a few powders but still runs the 55gr to 75gr area.
I have a 10.5 223 ar pistol and I just loaded up some hornady 55gr SP with 22gr of H322. I have not yet been able to test them through my chrono because of the weather but I have no doubt they will do great.
I worked up a load for my 7” 223 pistol that I love. It’s a Speer 70gr sp bullet with H4895. I used the reduced recoil recommendations from Hodgdon for the H4895. And I found that I got the best groupings at the lowest recommended reduced recoil specs. Very little if any flash. So don’t rule out H4895 for a SBR.
Gday JRB and crew, great vid bud, sorry to say it didn't quite make up for the personal touch from a classic Monday night Twitch from the past, but i do understand my Brother.
I have a 7.5 1/7 223 wylde barrel. I use N140 25.5gr at 2178fps, 30.4sd, 66es and a 62gr federal trophy bonded bear claw bullet loaded in LC brass. It works but I had to use a seekins adjustable gas block and an odin works heavy buffer with 2 tungsten and 1 steel weights to make it work. But that thing is quiet with the 7.62 asr can.
Modern Reloading 1st Edition has some very interesting loads for IMR 4227 in .223 Rem. I've only tested them in a 16.1 with 40gr and 55gr projectiles, but they work the gun (though the 40gr doesn't lock back).
Couple things to keep in mind. 10.5 is minimal length for a lot of suppressors So 11.5 to 14.5 is your most popular range. And yes there are several gas length options in that range. 14.5 mid gas is my go to
Man, this video answers some of my questions!!! You definitely should make some videos, about getting 16 inch barrel velocities in a 10.5 barrel with pistol powder, and still run reliable and SAFE 🙃😅
Threw the 8" and 12" barrels in GRT just out of curiosity with the 75 Hornady BTHP using max velocity as the sorting order. With the 8" barrel, this advice is spot on but you might add just a couple slower on the list, accurate 2330 to cfe blk seems to be a good range. By the time you move up to 12", you would be better with something like H4895, Tac, N135 range for velocity.
IMOP, cant beat W296 for 300blk. I use it for all loads/bullets and shooting both 7.5" and 16". My 7.5" shoots MOA 😁 with the Nosler 110 Vermegeddon and 125 Ballistic Tip. Not so accurate with the subs, unfortunately
That burn rate chart is misleading sometimes I have heard. But sometimes the most annoying thing is finding load data for powder that you know should work
Johnny i have loaded 223 with the cfe BLK and ran it in my FN 18in dmr 2 be extremely cautious on working up ur load on a longer barrel at 23.5 grain it completely destroyed my extractor paw in the bcg. I started at 18 grain and pushed it a little too far trying to get bolt lock on last round. Final loading that worked on a 18in for me and get bolt lock on last round was around 22g with a H1 buffer.gool luck with yous and hope this helps.
I had hopes that one of those Alliant bottles in the back would be 1200R. With the current powder and primer shortages, 1200R was all I could get a few weeks back.
Is love to see a series on this with maybe 10.5, 12.5 and 14.5 barrel lengths No one meaningfully uses the 8” stuff in 556. It is just tooooo short. 10.5 is the general minimum standard
Completely and totally agree. Wonder why Johnny is such an extreme opposite barrel freak? Always using test barrels that are too long for 300 BLK and now he's obviously going-to-go too short for 5.56. Look at what thr mfgs are selling ... 10.5-12.5 when it comes to 5.56. Let's test something in the middle like out of the SIG MCX Virtus with an 11.5" pipe. PLUS (and this is the really great part) it has adjustable gas. Imagine that Johnny. Welcome to the modern world and, don't get me wrong I love your affordable PSA guns (have known Jamin here in SC since he was selling surplus reloading supplies out of his metal shed in his yard in Pomaria) .... but it is time to test a gun with a gas selector valve.
you can get scary fast with leverevolution too just watch the pressures or it'll pop primers. I have discovered when pushing heavies out of my BCM 18in spr barrel I will pierce primers pretty consistently if I use cci400 I have to run WSR or Win Red or Rem 7 1/2
I just got an 11.5" barrel that I'm going to loosely copy the Colt 607. I am going to try to load 75 grn. GS checked powder coated cast bullets to somewhere between 2000-2500 fps where ever i can maintain appropriate pressures to run the gas operated bolt . So i would enjoy some input and trial and error information to help my project along . The barrel I got has a 1 in 9 twist so 75grn will be heavy but the fact Im using cast and not jacketed the bullets are considerably shorter than say the 75 grain Hornady BTHP I have.
I have found full house loads of even medium popular powders to jam up my carbine 14.5's and my 24 inch Varmint barrels on multiple occasions. Over gassed and suppressed set ups get faster powders in my residence. This is not just about velocity. Its about unlocking power, or lack thereof.
I haven’t loaded any cartridges for my SBRs, but if you’re interested in defensive bullet options for a 5.56 SBR, 77gr TMK is a top choice. Little to no neck, massive permanent wound channel, and consistent penetration, unlike 69gr TMK. 77gr TMK also has a silly low velocity threshold for consistent fragmentation, making it great from short barrels. An 11.5” could still get reliable fragmentation out to 300 yards and maybe beyond. Gold dots and TSX bullets are also good options, but are better if you’re concerned about barriers like car doors. They don’t have quite the same expansion threshold range of the TMK’s fragmentation range.
Hey Johnny funny your making a series on this because over the summer I had some RL 10X and 77gr Sierras laying around and had the same idea but couldnt find load data. I wanted to try it and ended up settling on 22.5 gr of 10X seated at mag length. I went all the way up to 23.1 but hit serious pressure with primer flattening and ejector marks. Thought I would share in case you had some 10X that you wanted to try.
Hello Sir. Absolutely love your videos. I was hoping you could clear up my absolute confusion about checking the lands. I just got into reloading. I followed some instructions on how to check it with a empty cartridge fitting a bullet lose and pushing it into the barrel until it stopped. Also used red loctite to hold it in place. Seemed simple enough. Only problem is the overall length was longer than 2.260 for my 223. If my cartridge is trimmed correctly at 1.750 can my overall length be longer?
I'm still waiting for someone to invent a powder that self regulates it's burn rate by pressure. Would be great to choose a powder by the pressure you want and you add more or less depending on barrel length.
My 10.5" SBR loves CFE-223. I am getting good velocity, averaging around 2661 fps with 62gr Speer Gold Dots over 27.3gr of CFE-223. My 18" only shoots the same combo @ 2867 avg. It is important to note, there are no pressure signs on either using #41 primers, and this is BELOW MAX for 556 load data and I am shooting it out of LC brass. BUT the fireball in the SBR is amazing and scary, thats why I only ever shoot it suppressed.
Good info. I’m getting 2760 avg out of an 11.5 with 62 gold dots, pp 2000mr near max load in speer data, lc brass and cci400. Any more I have slight pressure signs. What can(s) you using with that 10.5?
@@johnd1817 YHM Turbo K 556 can, and worth every penny, lol. Rifle is light, maneuverable, and I would venture to say hearing safe, I can shoot without ear pro and no discomfort. But I am half deaf already, so I may not be a good judge. I also dont do it often.
Those 75gr Interlocks are so badass I just wish Hornady would release the projectiles to the reloaders and I've told them as much I get the perk that they are local to me and I've been privileged enough to shoot with the Hornady folks
You'll be happy to know that all IMR powders contain a small amount of Potassium Sulfate, to help with reducing muzzle flash. Not sure exactly when they started doing that, but at least since the 80s. I think IMR 3031 has been popular enough to have never been modified. IMR 4064 has been popular, but I know they changed its formulation once. IMR 4320 has been pulled from the shelves... three times now? The third time was Feburary 2020, and it's still discontinued. :(
Great analogy! Here's one more. Imagine the car is on the edge of the cliff so you just shove it as hard a you can from standing still. The car doesn't move and your hard blows through the metal of the trunk an all that happens is you hurt yourself with no results on the car. Don't push too hard, it's dangerous
I use 23.6gn of 8208XBR under a 77gn SMK for my 12.5" SBR. MK318 is designed to perform in short barrels also, so that would be a good load to duplicate.
I took some 77gr SMK ladder test loads out in the recent heat to test for pressure and accuracy nodes. I found significant pressure indicators at 23.3grs of 8208XBR when using cci41s, no issues moving up to 23.6 with FED AR Match primers. Using Lapua virgin cases, 23.5 gas of XBR and FED AR match primers printed .75 inches at 100 yards, no pressure issues whatsoever in 90 degree heat and in a hot barrel.
Wow I just tried tac and cfe223 out of my 13.9 and had horrible results... Mayne I need a slightly faster burn powder man it would be nice to see some data on this topic different burn rates vs velocity qt 100 yards say out of 10.5, 13.7, 16" barrel comparison
Btw, I read that some powder gave a fireball because the case was not filled enough for pressure to improve burning. I do not remember which but I think it was some 223 powder.
using Benchmark with 40gr varmageddon I'm hitting around 2900fps out of a 10.5 but I have it screaming at almost 4000fps out of a 20. That said in cloning mk262 my 262 clones are my sbr ammo as well its slow but brutal in ballistic gel. my other goto is the Barnes MPG over 8208xbr 10x also does killer in SBRs especially 10.3 to 12 inches
A 7-10" .223 is about like cutting a .308 down to 12". You can try all you want, you're going to send most of you powder out the end in a fireball. That's 300blk territory. For 10-14" .223 you're best bet is going to be about H335 - N135 range for best burn to case fill (55-77gr). The clean burn and velocities I've seen out of N530 is unreal. On the pricey side but probably the best you can get for that application.
I would love to find some alternative uses for 300BLK. I've never seen anything other than 300 blackout. It's really only useful for subsonics I think.
Here’s my work up with TAC. 2650 ish FPS and 6 SD. www.thehighroad.org/index.php?threads/308-winchester-reloading-ramshot-tac-hornady-180-grain-sst.890039/#post-11968191
Another point to consider with short barrels. Bullet construction may dictate a lighter bullet for terminal ballistics. With the short barrels at a given range. Bullet efficiency may suffer beyond a given yardage. While still meeting the burn efficiency and accuracy.
So I was thinking, isn't this a thing?Remington was doing this back in 1963 with the XP-100, right? I just picked up my Hornady 7th edition and turned to the 22 caliber handgun section and found loads for the 221 fireball and 222 with 10" barrels and 223 and 22br both with 14" barrels. They all list alot of the powders you mentioned. H335, h322, imr 4198 and 3031.
I dont have much first hand knowledge on the subject, but according to ballistics by the inch heavier bullets seem to lose less velocity than lighter bullets. But I'm not sure what powders were used.
This was and is understood by generally everyone knowledgeable of reloading and especially Johnny. The weight of the bullet is limited by the cartridge dimensions and in balance with the powder type and amount used. You can't just use heavier and heavier bullets and powders that work well for medium bullets, as the peak pressure will climb dramatically with the heavier bullet moving slower at different microsecond stages of firing.
This was a pretty good video brother... I've always wanted somebody to break down the burn rate chart for how to use the burn rate to pick a powder especially for off label use or if that's not something that can/should be done... Some times you can find a bullet but the powders you have on hand or the ones available to buy won't be listed in the load data. I'm relatively new to seriously reloading and I've had to come up with the data on my own more times then I'd like... I'm using the burn rates to pick powders close to the ones listed and work up using the listed powders charge weights starting at the lightest charge or using other bullets/bullet weights load data and staring at their lightest charge weight... So far I haven't got myself in trouble but a couple times I've ran through a lot of components just to find out it won't work like I want and can't help but to think eventually I'm going to pick the wrong combination...
I use 1680 and 5744 in my 300BO, for a 8" SBR I would try 5744. It's not volume or position sensitive and is fast enough to give me slightly better velocity's than H110.
I think with carbine length 5.56 it’s pretty well established that 11.5-12.5 are the minimum you really want. IMI 77 gr chronoes 2550 from my 12.5. I think the ideal bullet would be the 69 gr TMK. Pick up 10% BC, pick up ~100-150 ft/sec in velocity, and it’ll still expand violently. With that in mind I’d be running H4895 if I were you. I remember it was quicker than you thought in the mk262 clone video
Depends 100% on the application. For general use, out to an occasional 300yd shot, sure. As Johnny said, this is for home defense/indoors use, which even a 7.5" barrel will get done. Will ideal frag and ap characteristics be common? Probably (of course) not. Like you expressed, loads for 11-13" are well established, too. It'd be a waste of Johnny's time to just duplicate the results that hundreds have already found/concluded, where 7-9" is a fair bit more exploratory.
@@EtherFox why would you bother with a 5.56 in a known finicky configuration when you could just do 300 blk? I’ve got a 7.75 300 blk pushing Barnes 110’s at just under 2100 ft/sec. 5.56 under 10.3 is a novelty and a bad one at that
25.7 gr of H335 with 55 gr bullet does a four foot long flash out of my 10.5 barrel with a flash forward muzzle device. PMC Bronze 55 gr factory does a 10 inch flash.
