There's the groups with h4831sc and h4350. Nothing great yet but the ones with check marks by them I'll mess with seating depths with one higher charge and one mid load with each powder and see if that tightens them up.
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Pressures?
- Thread starter RG300WSM
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Ive heard that barrels get faster velocity as they "settle in" but obviously new barrels wouldnt cause pressure issues.
I have had an order of bad bullets, oversized by a thou or two. Mic your supply of bullets.
I'll definitely take my chronograph next time. According to the berger book approximate max vel for 210 gr berger in a 300 wsm is 2,701 fps with a 26" barrel. Take into account my barrel is 22" and -27 fps per inch that puts me at 2,593 fps max for h4350 and 2682 fps max for h4831sc. Which means I was 70 fps over max velocity at 2661 fps with my old load which could have caused my brass to fail sooner because I definitely showed pressure signs at over 50 degrees..... So onto the next question how slow is to slow? Picture for how I feel...
Huntnful
Well-Known Member
If you weren't chronoing the fired brass, that felt like it was hitting pressure too soon, it was probably running the same velocity as the higher charges in the factory spec brass. You might just be over sizing and dumping more powder in for no reason. I normally see velocity and pressure signs directly related. The new brass could be absorbing some of that energy with the .008 shoulder growth on that initial firing. I wouldn't over size just to add more powder until you actually confirm the velocities from the fired brass with 58gr. and the new brass with 60gr.
Chronographs are a must as velocity is also a metric of pressure. Maybe you have good velocity at low charges? Likewise I would be cautious of higher velocity above published data in the absence of other pressure signs.
Another thing is maybe its just a matter of the combination of your components and your rifles chamber/barrel. I have a bullet Im getting a little lower than the velocity I expected but determined its just what the primer and powder I have on hand will give.
Bob Wright
Well-Known Member
I think 4350 is pretty fast for this. 4831SC I found to be good until it reached a pressure that made the velocity become unstable with random ejector marks. So Chrono is in order no matter what.
The other issue I had was a tight neck chamber. I ended up turning all my brass to get to .003-.004 chamber clearance on loaded rounds.
I also found RE23 powder calmed my rifle down as it is double based and easily achieved my same velocity requirement, where H4831SC was just not doable without being on the hairy edge.
Mine was a 7RM with 180 Bergers.
The other issue I had was a tight neck chamber. I ended up turning all my brass to get to .003-.004 chamber clearance on loaded rounds.
I also found RE23 powder calmed my rifle down as it is double based and easily achieved my same velocity requirement, where H4831SC was just not doable without being on the hairy edge.
Mine was a 7RM with 180 Bergers.
I'm going to have to get new brass out to use so would you guys shoot 100 cases with just whatever powder and bullets to fire form it to the chamber then do load development or shoot the new brass through a chrono and get a load that groups that is under Max velocity then try to match that velocity after I size it?
I would, since you can't really get down to meaningful load development without chamber-fitting brass. This why I chuckle about people hating AI chambering because of 'all the fire forming'. It turns out that All of your choices actually need to be fire-formed!
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Use that time fire forming to determine seating depth for your bullet. Have a factory 300 RUM that shoots .5 MOA with starting load under 210 HVLD and 215 hybrid but with different seating depths
Plinker147
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I've used new brass in load development and never had to change anything after resizing. Not always but I've had in happen that way for several rifles. So, I would use your 100 rounds to gain meaningful info like seating depth, pressure with the bullet you're planning on shooting.
I would only run the new brass necks thru your expander so you can assure your getting -your- neck tension and not worry about shoulder bumping the first firing. The difference in velocity between new and fireformed is negligible but neck tension could be more variable on pressure and velocity.
MagnumManiac
Well-Known Member
I never run powder tests on new brass…too many variables.
You're better off picking a powder down a bit from the top velocity performers, reduce the max load by 3 grains and do your seating depth testing first, then powder and primer testing. The results will astound most. Have done it this way for a very long time.
Cheers.
You're better off picking a powder down a bit from the top velocity performers, reduce the max load by 3 grains and do your seating depth testing first, then powder and primer testing. The results will astound most. Have done it this way for a very long time.
Cheers.
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Agree with MagnumManiac, don't do pressure testing on Virgin brass. I've gotten false readings even with premium brass. Too much stuff going on, yet that doesn't mean it can't have a great, stable, and accurate load.
Depends on cartridge to some degree as well. Belted magnums will always have significant fireforming need unless using new Peterson Long brass. The 300WM Long version was 0.003 shoulder difference new and no different than my fired brass. I use new brass to start my load development knowing full well adjustments may be needed but at least I am getting some benefit from fireforming the brass. YMMV
