Just to start, I don't load a lot of 9mm. For me, it's a utilitarian cartrige (conceal carry) and has no recreational use. Plus, factory ammo is (was?) fairly cheep, so I have a lot of it. But I've been loading for 36 years and have a lot of experience in general with AA propellants (save AA#9).
I assume "120/122gr target loads" is a lead slug. If so, you might want to try AA5. Your burns with the slower powder may not be as consistent, but the pressure curve will be more gradual, which bodes well for lead. Leading problems are common with 9mm.
AA5 should work really well for 115 GDHP's, and fairly well with 124 GDHP's. I have loaded 124 GDHP's with AA5. Yielded 1049 f/s though my Khar CW9 (3.7" bbl? I think) - which is 1f/s more than Speer's non+P factory offering. I wasn't comfortable with further increases in charge weight. This is well short of Speer's +P offering; which yields 1133 f/s in the same gun (the ammo I carry).
I had better results with Power Pistol. It's a tad slower and a lot more energetic than AA5. Great stuff that Power Pistol.
I like heavy bullets, so I never worked up 115's for high performance (emulating defense ammo). But I suspect AA5 would do well here.
Yes, I believe AA7 was "made for 9mm," but I think it was for carbines (i.e. Uzi's). Barrel length changes everything. I've never loaded 9mm w/ AA7. If I did, I'd only be for heavy bullets (147's) and/or long barrels. Not likely to happen. Now if I had a 357 Sig, that'd be a different story
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