Thread: 7.62x39 sub sonic loads

just got my hands on a Howa 20" in 7.62x39 and wanting to cook up some sub sonic loads for it. Hornady do the 225gn projectiles so thinking of using those but not sure on what type of powder to get (or what's available...) also open to use other weight pills if anyone has any recipes i could start with?

Watching with interest… just had some 151g casts arrive and haven’t reloaded at all for this rifle

I'll do a big post when i get more time. Ive just spent a couple of weeks playing with the 255gr subx pill (heavily modified) in my 7.62x39 ruger.
Heres a big red hind i shot Saturday @ 25m in public Bush.

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.

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.

Only subs (and some supersonics) I've ever bothered with have been cast, propelled by shotgun powders red dot, blue dot and unique. I tried trailboss when it came out
but found it extremely dirty and no improvement over what I was using. A lump of lead works pretty well if it's in the right place, same as any bullet really

Originally Posted by Scott Cowan

Watching with interest… just had some 151g casts arrive and haven’t reloaded at all for this rifle

4-5grns trail boss will see you right.

You won't be able to use trailboss behind the 255gr subx , as it wont fit in the case behind the bullet. I tried.

Originally Posted by 338Lapua_cam

just got my hands on a Howa 20" in 7.62x39 and wanting to cook up some sub sonic loads for it. Hornady do the 225gn projectiles so thinking of using those but not sure on what type of powder to get (or what's available...) also open to use other weight pills if anyone has any recipes i could start with?

What twist rate.dows.the Howa have?

Here some of my load and results. Pic heavy to save phone typing .
I pull the 123gr fmj out of this Chinese ammo and store the powder. Then reload with HiSkor800x and put a Modded 240gr Sub-X pill in.
3 step projectile trimming process. Bench linisher 5mm off, then in lathe to trim to 1.300" , then drill to get a bigger holllow cavity and tune the weight to 240gr.
Take note that the cold & fouled bore shot is around 930fps so i have specially loaded some 10gr for cold fouled bore barrel state.






And this shows why trailboss is not suitable for the 255gr subx pill

My Ruger 16" barrel measures at 1in10" twist, which isnt enough to stabilise the 255gr subx pill which is 1.540" long.
This is why I trim them to 1.300" long, also it helps give decent expansion at subsonic velocity.
The lead-alloy seems too hard for subsonic use imho, if you look at the recovered bullet from the pictures above you can see decent expansion , however this is after going front on through the neck/spine and lodging against the spine on the offside behind the top of the shoulder blade.

Here is a link for a subsonic stability calculator:
https://sharpsbros.com/subsonic-bull...ty-calculator/

As has been stated, no need or use for TB in this case for heavy subs. Similar to the 300blk, even with more normal powders, there just isn't the case capacity to get such a heavy projectile going supersonic.
Interestingly, well before the .223 progenated the .300blk, the 7.62x39 progenated a subsonic round known as the 9x39. It is likely that while the 300blk is largely inspired by 7.62x39, it also derives some inspiration from the 9x39.
@Ammo Direct NZ also stock a factory 255gr subsonic load, @338Lapua_cam you can pick up a packet just up the road in Whanganui if you order online ahead of time. Might be a good way to gauge the suitability of the 255gr projectile before buying 100 to risk having 90 left over that are no good to you.

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

Yeah, it's a bit of an interesting question. 255gr will usually go straight through unless you hit something bloody solid - the 170gr Sub-X has a serious amount of penetrating ooomph (I shot one into a block of wood in the wife's garden and it went straight through and I still haven't found the pill after digging down over 40cm so the 255gr is more of the same!

If the lighter pills are going straight through unless they hit something as well, I'm not too sure what the gain is going for an extra 105gr except maybe recoil...

Originally Posted by Micky Duck

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

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