Load development and Optimum Charge Weight of 308 Winchester and IMR 4895 powder with Sierra 175 gr Matchkings. I also evaluate the ability of the RCBS Uni Flow Powder Meter to meter the load with accuracy.
Very interesting video. I never thought of doing a range of powder drops and figuring out the info on them. Thanks for doing all this and sharing it with us.
Very nice & thanks for the info. I haven't done reloads for 30yrs. but decided to start again. One major problem I have w/your technique's, Man pick some decent weather to shoot in for crying out load. So in summary, I would wager a fair amount to say. No matter the conditions, what ever your aiming at will be in a world of hurt, but only for a very brief amount of time. Again thanks for the info on the technique especially on the powder measure. When I used to reload I always used the scales for every load.
Thank-you for your research. I use IMR 4895 in a 220 swift, 34.5 gr. With a 63 gr soft point It worked exceptional for hunting, pressures were fairly low, the rifle I used at that time was an m77 Ruger, ......
Depending on distance, firearm weight and shooting technique faster bullets will tend to impact lower than slower ones because they exit the barrel sooner during the recoil cycle. This tends to be observable from about 200 to 400 yards, closer an you need a half minute rifle or better to really see it and at longer distances a faster bullet will arrive on target sooner and so will start to impact higher than slower bullets, these distances are approximate not written in stone, shooting technique affects this a lot though.
Case pressure was because of military brass Less case powder capacity Get rid of Powder Thrower Use the scale only or buy RCBS charge master digital scale 42.0 of IMR 4895 with 168 MK has been the Load for 50 years in the 308 Win.
I was learning that using the ladder test protocol where the velocity flattens out as powder charge goes up is where to investigate a load with low standard deviation. I believe this addresses the issue of impact being lower as velocity goes up.
A comment on the powder measure: If you pause with the lever up...and dispensing meter full of powder, then it doesn't matter nearly so much how you run the lever so long as you hit it at the end of the stroke and dislodge any powder that is in the meter. Your briefly letting the meter fill will be all over the map...relatively speaking...as the powder does take some amount of time to fill. Let it sit full between loads and then the only variable left is the height of powder in the reservoir...which you'll want to keep at a consistent level for best results. My Hornady measure (basically identical to yours) will throw within .1 grains especially with ball powders. The IMR long extruded powders tend to hang up a little bit as the cylinder tries to cut a grain now and then. Throw out any measures that had a hitch in the throw...and you'll find your consistency will be much better.
The drop in poi is due to recoil and velocity theBullet being in the barrel longer hits higher. Faster gets out without much rise. To test put your hand on the scope and hold it should shoot lower.
+Mickey Ross If you go to the Hodgon website, they have load data for all of their powders. You will have to try and see what load works best in your specific rifle. My sweet spot was towards the lower end of their suggested range. Unfortunately not all guns respond the same and a good load for my rifle may not be a good load for your rifle. As someone told me "Bolt guns have personality" which I find to be very true. Also, there is IMR 4895 and H4895 which are two very different powders so make sure you are looking up the correct one.
If you zeroed your rifle with that load under these weather conditions and then in theory didn't touch it till summer took it out and shot would your pint of aim/ impact be the same? Or how big of a difference would it be? I've read many forums and guys saying imr4895 to not be very temp stable. What's your experience with this?
The point of impact does change with temp, but the point of impact also changes due to air density. I have not ran the chrono on the hottest summer day I could find to see the velocity change. I cannot confirm that the point of impact is moving because of a faster powder burn, or because summer has a higher density altitude number ( lower air density). I use the same load for that rifle and it works well for me. I also read the same about that powder. I have read that a lot of people like Varget as it is to have less temp issues. I have not had good luck with Varget at holding a good group but that is just me and my rifle may not like it. I am not implying that this is the perfect load or perfect powder, It was more to chronicle the methodology that I used to arrive at this load. This load may not be safe in your rifle and each shooter/reloader needs to take anything they read/watch with a grain of salt. My info included. Each person is responsible for their own safety and needs to work up their own load for their rifle. Thanks for the question.
As far as a velocity recommendation, I really don't have one. As someone once told me "Bolt rifle's have Personality, each one is unique." You need to find what works best for your setup. My personal experience is that my rifle does not like hot loads when it comes to reputability.
Would of been good to publish the velocity information off your chrono as that would yield significant amounts of information on your shot-to-shot performance. Otherwise it's a great video!
I'm a bit perplexed. You state that 41.3 to 42.1 grains of IMR 4895 had the most stable position. My Sierra published load data lists 41.5 grains as the maximum load. for 175 gr MatchKings Even your lower range loads in that grouping exceed the maximum safe load pressures. In 40 years of reloading over a dozen calibers I've never even loaded a maximum charge, let alone exceeded it. Please explain. Also, fo less than the cost of an average video camera you can purchase a RCBS ChargeMaster dispenser and digital scale that work together. I've had one for over 20 years now.
When I develop a load, I will investigate a few different sources. I also have the Sierra manual but I also went to the Hodgdon website and looked up their load data. Their published starting load is 41 and their max load is 45 grains (compressed). It referenced the 175 grain Sierra HPBT bullet. I also have a Speer manual, but there was no reference for a 175 grain bullet. I went and looked at all 3 (Sierra, Speer, and Hodgdon) for the 168 grain bullets. The sierra load data was considerable lower than the other 2. I chose to use the Hodgdon published information for the load development for the upper end, and then felt comfortable to go lower than their published because of the Sierra data. With developing any load, you need to look for pressure signs. When I started getting into the mid 44 grain load, I started noticing pressure signs so I stopped and did not go to the 45 max. That's how I ended up testing 40.5 up to 43.3 grain for accuracy, again, I was steering clear of where my rifle started showing pressure signs. With those limits established, I proceeded on with load development for accuracy. Moreover, the video was to outline how I developed the load for my rifle. My opinion is that Sierra load data is very conservative. That's not bad, it's just for liability. Hodgdon data seems to get fairly hot. Regarding the Chargemaster, I purchased one shortly after I published this video. Works great for load development. Statistically, I don't think it is necessary, but it is very nice.
Reloading manuals are not really the maximum .......they were watered down back in the late 60's. If you would like real data find a mid 1960 speer reloading manual .
IMR 4895 was the M852 original powder........also used for years on the Palma Match courses. 44.8 with 155 MK (1992 Palma Match load with RWS 5341 and 92 Palma Brass made by WW. 42.2 with 168 MK is M852 load in LC brass I sold my powder thrower RCBS quickly. ...........went digital and electronic RCBS
The video is shot with a Leupold Mark 4 spotting scope. The scope on my rifle was a Leupold Mark 4, but I have since changed to a Nightforce NXS F1 3.5-15x50.
My stock barrel 700 .308 shoots tighter groups then this. I ran 41.6gr 42gr 42.5gr 43hr 43.5gr 44gr 44.6gr and 45gr of 4895 and shot moa or better. Shooting mixed brass br2 primers and 150gr hornady sst.
TexanUSMC8089 I also use 4064 at 41.3 grains with 165 gr. projectile. I haven't tried it out past 100 yards yet but it does real good for what I am doing with it at 100 yards.
