.300 Whisper Pistol Build

[abyssdncr]

Made it out this afternoon with a new batch of loads. Mounted a Bushnell 3-9x40 off my 10/22 to a YHM riser mount and shot some groups at 50 yds. Based on my last outing, I upped the AA9 charges and loaded in 0.2 grain increments from 8.9 grains to 9.7 grains. I was using an Adventure Arms 20 round mag and loaded 5 at a time; all loads locked the bolt back on the last shot and zero malfunctions of any kind. Woo hoo!

Not sure if this data is useful for anyone else, but here's a summary of the Chrony data:

Case: LC 5.56 Fireformed
Bullet: Hornady 190 gr. SP, seated to mid cannelure
Powder: Accurate Arms 9
Primer: CCI BR4
Charge Wt 8.9 9.1 9.3 9.5 9.7
Average 1001 1013 1034 1060 1098
Spread 43 24 34 28 27
Std Dev 12 8 10 9 7
50 yd Groups .73"* 1.40" 1.08" .65" .93"
5 shots* .79" 1.03" 1.06" .80" 1.01"*

*First shot of the day went 40 fps faster than average and outside of the pattern by about 1.5", so I tossed it from the data and group measurements; one shot on the last group went wacko wild by 2"...???

Also shot 5 rounds of my Speer 125 gr. SP hunting load from last year. It gave me 1.25" 5 shot groups at 100 yd last year before season with velocities around 2100. Out of the 8" barrel average velocity was 1694. The first shot went 2.6" high of my 50 yd zero and the next four went into 0.35".

Uh, yeah...there's a big difference in recoil with the super loads! Not sure just how much extra gas the system was getting with this load, but I decided to hold off on the 155 gr. super loads until I get the valve installed to turn down the gas.

All in all, success! Now I need to give it a good scrubbing, because the action is pretty dirty now. Next up will be to experiment with some leftover 178 gr. Hornady AMax.

Happy shooting!