Thread: 7.62x39 sub sonic loads

Originally Posted by No.3

Should be able to find a fast pistol powder - Red Dot is a good one if you can find it. TrailBoss is obviously the default, but you might struggle to find it in sufficient quantity.

As far as loads, the 7.62x39 is a lot smaller in volume to something like the .308Win - so usually would require less powder all things proving correct. My 20" .308 is using 9.5gr of Red Dot with a 170Gr Sub-X pill at 1040FPS if memory serves correctly. I think for the similar speed in the smaller case with a similar weight of pill it was in the region of 6gr.

As far as loads with the fast pistol powders, you can't really go too light in grains of powder and cause a safety issue with ignition of the powder and pressure - the safety issue is not having enough pressure to clear the pill out of the barrel. If you jam a pill in the barrel and fire another - it usually isn't good. The usual advice is to start at the highest load recommendation without the suppressor on and work back until you have reached the velocity you require and have confirmed stability. Then check the velocity with the suppressor fitted as you can end up gaining a bit of speed.

When loading with fast powders, you can run into pressure issues with too much powder as the pressure curve is very steep (like vertical) then quickly dropping away - which is quite different to standard rifle powder loads which come up to the max pressure comparatively more slowly and then drop away in more of a curve. Too much fast powder is possible instant bomb. Within standard loads like a '08 length case it's safe - for reference there is a 'standard' reduced load using Red Dot of 13gr and standard weight pills (150-180gr) which is good for about 1600fps or so depending on the pill and I've never heard of any dramas with that amount.

I never had much luck with subs until I started crimping the necks lightly, then everything got a lot more reliable and groups tightened right up.

I've got this Green dot (500gms incl container) & Lil gun (same) if anyone's interested. I picked these up a few years ago with the same idea to do subs in my Howa x39 but never got around to it. I did use it for loading a x39 brass shell, powder, cotton wad & a piece of brass ball cock arm as a crimped projectile to use in a diving friends power head spear (apparently worked great)
I'll be heading up tp the waikato in mid October if that helps.
I'll put some other powders up on Buy/sell etc soon as well as these.
Phil.