Originally Posted by Zombie Steve
Scientific Wild ___ Guess
If the manuals are showing you different things, you need to remember that powder charge is only one part of the equation. Look at the brass they used, the primer, the test barrel (they are probably testing a 24" barrel and you're shooting a 16" barrel), bullet shape / weight, seating depth... all have an effect on the pressure (well, not barrel length... but it does impact velocity).
What velocity are you looking for? My plinker 55 grain load only does 2,850... which is what PMC, American Eagle or Wolf ammo is going to get. You just aren't going to get to 3,000 fps with that bullet and a 16" barrel. Don't go chasin' nato loads with canister powders... particularly not with a fast burning powder like AA2230. I my opinion, 2230 is just about right for 50 grain bullets and below. Get into the heavier bullets and you want a slower powder.
I was looking for something similar to m855. My thinking was I am using the same bullets, same cases, same primers. I believe at the same length aswell, though I failed to write down my xm855 length so I could be wrong on that.
I chronographed xm855 at between 2861-2956. Relizing that this is nato spec ammo, I wanted slightly less velocity, seeing as they are using crimped in primers, and brand new brass. That is what I achieved at 24.4 gr. At 24.4 gr of aa2230 I achieved 2886 fps on the high end. That is basically what I got, slightly less than 855, and still apparently within a safe loading range. This was using the same barrel, very close to the same distance away from the chrono, and in very similar temperatures. My load also produced better accuracy than what I was getting from xm855. Now I have two published sources telling me I am on the mid to low end, source dependent.
Again I am not seeing any pressure signs in the brass or the primers. But I still do not know what sort of pressure I am getting. Judging from my lyman 49th edition I am apparently under 50,400 c.p.u. (thanks for reminding me btw) with a barrel that is rated for 65,000 cpu IIRC. But how far under?
I would love to go back to ramshot tac, but that simply is not an option for some time apparently.
Something else I saw. Was aa2230 is very similar to ramshot x-terminator. At least as far as loads go. This powder (ss2230) just has me all sorts of discombobulated apparently.