Re: 7mm Allen Magnum/RL33/180 gr Berger testing
When I designed my 7mm AM, I played with designs nearly exactly like yours, moved my shoulder forward 100 thou, did not go that extreme on shoulder angle because I have seen some serious issues with these extremely sharp shoulders with powder bridging and as the cases get older, they can get a bit finicky with shoulder collapse when bumping the shoulder.
Also found that there was no increase in performance over my design so kept it as is.
Anyway, I am a bit surpised your not seeing more velocity. My 7mm AM in my Raptor rifles is easily pushing the 190 matrix to 3400 fps in 30" barrel lengths. My personal light Raptor T-Hunter will push them to 3350 fps and it only has a 27" barrel length. These are using RL33.
If your looking for a powder between RL33 and WC872, you may want to try US869 from Hodgdon. I have found its a bit faster burning then most lots of WC872 but lots of WC872 can vary ALOT depending on what you get. I have seen it noticeably slower then US869 and some lots nearly identical so just depends on what you have for burn rate. Guess that's what we get with the lower price.
Not sure if it will work and you WILL notice velocity variation shooting in different temps with all of these ball powders. Sometimes DRAMATIC variation with a chambering like this.
Your pressure issues with RL33 may be your shoulder angle. Hard to say but I am surprised you can not get more velocity with your barrel length.
H-50BMG would probably be ideal in burn rate for your application but unfortunately, this powder is so bulky, I would say you have zero chance to get up to top working pressures and I would suspect powder bridging would be a serious problem.
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