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Muzzle PSI and pressure curves

Posted: Tue Aug 09, 2022 4:26 pm
by Demphna2
Alright, I just ran some numbers using GRT.
Currently doing load development with N105 and 190 gr Sub-X. COL 2.09. 6.5" barrel with V7 proprietary gas tube (shorter than pistol gas).

8 gr of N105 got the bolt 2/3rds of the way back. Muzzle psi was 6880. If I seat out at 2.24 at 8 gr, muzzle psi will be 7280 and velocity will be around 1000 fps.

Ran data with my N110 loads seated at same COL and the lowest charge I tried was 8 gr at just below 900 fps with a muzzle psi of 5800. Those cycled and held the bolt open.

Does this have to do with the different powder pressure curves? And how does this play out with how quiet a load is? Less muzzle psi should mean more quiet. I'm assuming the difference is in the percentage of powder actually burned?