Originally Posted by SDGlock23
Concerning AA9, maybe I'm the oddball here but I never get anywhere near the listed velocity using any of the AA powders (in 10mm anyways), well except that I've not tried AA7 yet. AA5 for instance claims essentially 1200 with a book max load from a 5" bbl, and I only get south of 1050 fps from the 20. AA9 claims almost 1250 fps with 13.5gr but with 13.2gr I'm not even touching 1150 avg from my G20.
Granted I need to work up some more loads for it since I haven't dealt with AA9 much at all, but it seems like a lot of powder for so-so velocity. 8.0gr Unique was getting me the same velocity as 13.2gr AA9, roughly 1145 fps. Too bad Unique isn't the most consistent metering powder out there. It's also too bad striking oil in the backyard is easier than finding a jug of 3N38, because 11.5gr of it is getting me a 1350 fps out of a 180gr JHP from my stock G20, which is a little faster than what I like to push a 180gr, but the point is, it works very well.
I too have found Accurate's data to be a bit optimistic for A9. Hornady is a bit closer to what I see with XTPs in my G20. I typically pick a spot between the two maxes (although I don't think you could get 14.9 gr under a 180 XTP if you tried to work to Hornady's max). For a 200 gr, that would be about 13.0 grains @ 1200 fps. 14.0+ starts getting the 180 moving. Lots from a few years ago (made in Belgium) had some temp sensitivity, so that could be a factor.
The weird thing that I've noticed is that 180 and 200 XTPs go almost the same speed for a given charge. What that tells me is that Accurate no. 9 likes neck tension. The longer bearing surface (higher bullet pull) of the 200 lets the powder "spool up" a bit, or so it seems.
The other thing about Accurate no. 9 is that it has been manufactured by different companies over the years. It has changed a bit. The latest USA-made version seems to be a bit more dense. In my small sampling of re-works, I've noticed similar results as far as velocities, groups, velocity variations, etc. The newest batches have shown some signs of being less temp sensitive.