Hi,
to throw something else out there.
Take my example in the post above. Using QL I noted the calculated muzzle pressure just as the bullet exits the muzzle for these particular loads (in brackets). Now the muzzle pressure will affect the behaviour of the barrel during recoil. So note that the last powder has 20% more muzzle pressure.
S335, 65.2gr / 98% fill / 67 243psi / 2 500fps / 1.191ms barrel time (6 744psi)
S355, 66.4gr / 99% fill / 57 526psi / 2 500fps / 1.254ms barrel time (7 728psi)
S355, 71.0gr / 105% fill / 50 054psi / 2 500fps / 1.294ms barrel time (8 112psi)
I need to tell this story. I simply could not get my Sako .375 to shoot. I bedded the action (and I do know how). I threw plenty lead down range until I read an article on larger bores requiring more free floating space between barrel and stock.
I opened the stock out and matters improved significantly but with one powder only??? I happened to have two different loads (powders) at the range and noticed that when shooting the one load that my rifle sounded like being slapped with a wet fish yet was fine with the other load. I slipped some cardboard in at the tip of the forearm to wedge the barrel and the sound went. The sound of the wet fish was actually the barrel slapping against the stock causing wayward shots.
It was then that I realised that one powder was recoiling more / differently for the same given velocity. I opened the barrel channel and the rifle became a 1MOA heavy calibre which was perfect for me as I am not a great shot, and it takes a little taming over a bench. I actually managed a three shot group of .241 MOA but consider this fluke as I have not gotten close since. My best group for any calibre.
So powders in my opinion can affect the muzzle behaviour and therefore accuracy.
