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I've been working on a 9mm load for awhile now and finally found what I think is the sweet spot for accuracy. The target below shows 17 rounds fired from a measured 25 feet using an S&W M&P9c (3.25" barrel). The shots were fired using a pistol rest (I'm not nearly that good free hand).
The load is 6.0 gr of power pistol, 115 gr. FMJ, CCI 500 primer. The bullets are from Precision Delta. The 6.0 gr load should give about 1,125 FPS. Anything less than 6.0 grans is definitely less accurate. In fact I was very surprised by the difference .2 grains made.
I started out using 4.8 grains and they fired okay, but the groups were really spread out. The accuracy improves as a direct function of powder weight up to about 5.8 grains. Then at 6.0 grains there is a step increase in accuracy. Not sure but I'm guessing that the difference is sonic velocity. I don't have a chronograph, but the Hornady data indicates sonic velocity is reached at about 6.0 gr. of power pistol.
The load is 6.0 gr of power pistol, 115 gr. FMJ, CCI 500 primer. The bullets are from Precision Delta. The 6.0 gr load should give about 1,125 FPS. Anything less than 6.0 grans is definitely less accurate. In fact I was very surprised by the difference .2 grains made.
I started out using 4.8 grains and they fired okay, but the groups were really spread out. The accuracy improves as a direct function of powder weight up to about 5.8 grains. Then at 6.0 grains there is a step increase in accuracy. Not sure but I'm guessing that the difference is sonic velocity. I don't have a chronograph, but the Hornady data indicates sonic velocity is reached at about 6.0 gr. of power pistol.
