Thread: 7.62x39 sub sonic loads

Originally Posted by Micky Duck

When a 151 grn goes through n through I fail to see need for 200 plus lol.

Probably the main advantage, and it is relevant in that it is hard to get TB powder right now, is that you don't need to use TB powder to get subsonic speeds. Call it a work around that doesn't compromise on pentrating ooomph.

There are some wicked hollow points made for the M1 carbine something like hundy grain. Years since seen them but cavity was 11 mm deep.

There is plenty of trail boss around... Folks just not parting with it lol.

Originally Posted by longshot

Probably the main advantage, and it is relevant in that it is hard to get TB powder right now, is that you don't need to use TB powder to get subsonic speeds. Call it a work around that doesn't compromise on pentrating ooomph.

Yeah we never really did. What it did do was sort of bring everything up into the light as it were, with a bit more safety than the old ways and no arcane drilling out flash holes or weirdities like that.

Originally Posted by Roarless20

Yeah i agree, and i would love some cast ~100gr pills for subsonic possum medicine. Cause I definitely wouldnt shoot a possum with the 240gr

Also Mickey you know that 'need' has little to do with why we play around with different loads and cartridges

Hornady .309 90gn XTP?

has the 1:9.45 twist rate

a good bit of info here lads, thanks for that. but yes trail boss is not something that can be easily obtained so will be looking at alternatives.

Originally Posted by Pommy

The 225gr Hornady bullets are .308 ones right? I would skip those and start off with the 255gr SubX like Roarless20 has. They're the correct diameter for the bore. Bonus they're 30gr heavier.

A bit of AR2205 or pistol powder should be all you need for them in a bolt action.

yeah sorry about that, meant to type 255gr not 225gr...

Originally Posted by 338Lapua_cam

has the 1:9.45 twist rate

I wouldn't risk shooting standard 255gr subx with that twist rate with a suppressor on .
I checked the numbers for you vs that calc i linked:

Originally Posted by Micky Duck

When a 151 grn goes through n through I fail to see need for 200 plus lol.

Yes, the increase in energy between the two bullets at the same is speed is only 100 or so ft lbs. Subsonics need a different mindset I think. Expansion only really occurs if bone is hit even with the flash expensive jobbies otherwise there's a leaky hole with virtually no tissue damage. Flat nosed bullets seem to perform best. There's no need for streamlined stuff subsonic. 174 gr mk V11 303 fmjs loaded backwards are pretty impressive.

Didn't Keith extoll the virtues of flat point bullets for cutting good wound channels using Pistol calibres and cast bullets? Back in the 30s or when ever? Translates well to rifle subsonics

Pretty definitive contemporary article right here from our very own world famous Naki-ite

https://www.ballisticstudies.com/Kno...allistics.html

The mindset thing is similar to using a bow. Got to hit animal just right,be prepared to shoot again and wait for it to bleed out if chest shot...spending more on Lehigh projectiles seems to give big increase in performance but that price tag...yeah nah not for me lol.

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.

OOOPS here's the photos

PM me if you want any.
cheers,
Phil.

Originally Posted by Marty Henry

Yes, the increase in energy between the two bullets at the same is speed is only 100 or so ft lbs. Subsonics need a different mindset I think. Expansion only really occurs if bone is hit even with the flash expensive jobbies otherwise there's a leaky hole with virtually no tissue damage. Flat nosed bullets seem to perform best. There's no need for streamlined stuff subsonic. 174 gr mk V11 303 fmjs loaded backwards are pretty impressive.

I think that's why Robert's 151gr cast pills seem to perform so well. Bloody great hole in the front end which is virtually flat...

I've seen a few rounds made up with the .303 FMJ pill loaded backwards - for some reason very unreliable performance from them. Some tumbled and went sideways through things, some flew straight - I have no idea what the problem with them was as I've heard a lot of people put forward that they are quite good performers.