I found that my conditions here since I am so far above sea level as well as atmospheric conditions play on how fast and how loud my loads are.
Edit works in pistol 8.2 Noveske, AAC Micro 7, and H&R
Load data is
208gr Remington's
10.5gr A1680
2.120 OAL
I am above 6000ft and shout around 9000ft above sea level. I cannot measure speed but can measure the sound of sonic crack. I could probably go even lower than this and still cycle the noveske with the SDN6 on it.
Last edited by redfernsoljah on Tue Apr 16, 2013 10:53 pm, edited 1 time in total.
- Steve
Misspellings and grammatical errors courtesy of my Ipad Mini.
DO NOT USE UNIQUE for 300 BLK loads! I had excess pressure signs including burst primers in the area of 900 fps using Unique and wildly erratic velocity swings with any powder charge weight. try 9 - 10 gr of VVN110 with 220 to 225 gr bullets.
Also, the only thing that matters in regards to the speed of sound is temperature. Altitude, humidity etc. have no apreciable effect.
"Those gun control activists advocating exchanging a liberty for safety should recall that the safest place on earth is solitary confinement at Leavenworth."
- Rand T. Lennox
Here's a unique powder group with my Remington Model 700 as mentioned on page 1. I believe it was a 6 shot group. Nicely quiet when shot suppressed. The beauty of shooting a bolt action rifle or single shot in 300 BLK is that one can try all sorts of load combinations without having to be concerned with it functioning semi-auto.
Hey LEO- if you're only loading for a bolt, try IMR4227. Around 10.0 grains pushing a 220 grain pill works for me and is much more consistent than A1680, and quieter too. It just won't cycle an AR. From a non-cycling AR, I've been getting an average of about 1020 fps and SD in 10 shot strings in the 13-16 neighborhood with 10.0 grains of IMR4227 and SMK 220 pills. WHat is the twist rate of your barrel? 1:10 probably won't spin a 220 SMK enough for use with a suppressor, but I'm betting you already know that.
Get some VVN-110 and start at 10 grains and work your way down. My load with a 208 Amax is 8.6 grains. Less of a faster burning powder is quieter than more of a slower burning powder to get the same velocity, and with a bolt action you don't need slow powders to cycle the action.
OK, thanks for answering a question I was going to post. Less of faster burning is quiter than more of slower burning powders. Makes sense. Thank you. Now I just need to find more powder...
Thanks guys! Just starting down this path myself. I have a manual operated only AR with integral suppressor I built on a Form One.
Tried 180 Nosler and 7 gr of Unique. Too loud but sub sonic.
None of the previously mentioned Unique issues. Slightly flattened primer. Perhaps the poster has too long of brass and is getting high pressures from difficult bullet release??
