Post by GLSHOOTER on May 12, 2016 15:41:53 GMT -8
I would say that looks and is are two different things. We can get the same speed out of five powders. Cool but getting there is a whole different pressure world. Some behave nicely and act pretty linear on pressure. Others are as spiky as a horny porcupine. Not good. The 1680 is VIOLNENT when it comes to spikes. RL7 nice and mild and easy to work with. 2200 is a good one for lighter, 125 or less, bullets but not ideal for the 150's. I would not use 1680 much over 110's if I even wanted to. Just too many other better choices.
At one point I loaded up some Lil’Gun using 7.62X40WT data for a given bullet weight. The A-30 is much bigger in capacity yet on the first shot smoked a primer and on the second shot blew it smooth out of the case. The Lil’Gun went back on the shelf for the SOCOM.
If you want to play the game look at 7.62X39 data and use that as a start. Don’t go crazy but don’t just say XXXX speeds means YYYY and ZZZZ powder are close. Not happening. Ritch did quite a bit of testing on pressures on various bullets and powders. We abandoned what was too hot or crazy acting at the top end. The vagaries of the A-30 are that is low capacity and big bore. You trade fast powder spiky pressures with slow pushy ones that may not reach your desired speed.
Don’t go wandering off reading about someone else’s versions of this cartridge as they ARE NOT THE SAME! We have the largest capacity on this one. We have barrels proven to shoot at lower pressure. We also have data that has been tested and SHOT not just run through QuickLoad. I compiled all this as we went and we arrived at viable limits or suggestions. Admitted we didn’t shoot every powder and we didn’t go for case melting levels. We went for safe sane numbers that we knew everyone could live with.