7.62x39 subsonic Loads

[MagnumPI_357]

Hi Everyone,
I have been reloading for this rifle for a while and I'm getting a moderator for it soon, I really wanted to try some subsonic lead loads as I think it would be ideal at my local 50m range. Its a AIA bolt gun taking slightly modified AK mags, its 1:9.5 twist .311 barrel should stabilise most bullets under 1000fps.

I've never downloaded rifle rounds before and I'm a little wary after seeing clouds of toilet roll flying down range and bent bolts!
Trying to avoid that I've done some searching and found lots of people talking about it, but cant find any specific load information.
Has any manufacturer ever publish subsonic rifle data?

Many thanks from across the pond

Anthony

 

[n2omike]

What is the twist rate of the barrel? If you want to use heavier bullets, it will need a fairly quick twist rate. If you use standard 123-ish grain bullets, it will have about the same power as light 9mm pistol loads. Could still be fun for plinking, practice and small game.

 

[MagnumPI_357]

The twist rate is 1 revolution in 9.5inches

What is the twist rate of the barrel? If you want to use heavier bullets, it will need a fairly quick twist rate. If you use standard 123-ish grain bullets, it will have about the same power as weak 9mm pistol loads. Could still be fun for plinking, though.

 

[n2omike]

The twist rate is 1 revolution in 9.5inches

300 Blackout is the subsonic kissing cousin to the 7.62x39. It was developed to be a subsonic cartridge able to stabilize longer, heavier bullets. It can be had in both 1:7 and 1:8 twist rates. To see what your gun will work with will require testing. I wouldn't invest in large quantities of long, heavy bullets until you've seen if your longer twist rate can stabilize them at subsonic velocities first. Good Luck!

 

[GeoDudeFlorida]

Hi Everyone,
I have been reloading for this rifle for a while and I'm getting a moderator for it soon, I really wanted to try some subsonic lead loads as I think it would be ideal at my local 50m range. Its a AIA bolt gun taking slightly modified AK mags, its 1:9.5 twist .311 barrel should stabilise most bullets under 1000fps.
View attachment 1181593
I've never downloaded rifle rounds before and I'm a little wary after seeing clouds of toilet roll flying down range and bent bolts!
Trying to avoid that I've done some searching and found lots of people talking about it, but cant find any specific load information.
Has any manufacturer ever publish subsonic rifle data?

Many thanks from across the pond

Anthony

She’s a beauty! Built on a No.4 action, I hope? Not that building on a No.5 action would be a bad thing I suppose…
Do you know if they kept the original Enfield barrel/rifling and just cut back the chamber? Savage used a 1:9-1/2 twist on their 6-groove barrels; every other arsenal used 1:10 or 1:10-1/2 (Longbranch. Canucks had to be different)
I would say use any bullet in the same range as the heavier .303’s; 220gr, IIRC.

Edited to correct typo. Longbranch arms factory never made 1:20-1/2 barrels. Phumble phingers.

 

[MagnumPI_357]

She’s a beauty! Built on a No.4 action, I hope? Not that building on a No.5 action would be a bad thing I suppose…
Do you know if they kept the original Enfield barrel/rifling and just cut back the chamber? Savage used a 1:9-1/2 twist on their 6-groove barrels; every other arsenal used 1:10 or 1:20-1/2 (Longbranch. Canucks had to be different)
I would say use any bullet in the same range as the heavier .303’s; 220gr, IIRC.

Thanks, I think the Aussies made it from scratch, the mount points for the rail are integral to the action.

 

[MagnumPI_357]

300 Blackout is the subsonic kissing cousin to the 7.62x39. It was developed to be a subsonic cartridge able to stabilize longer, heavier bullets. It can be had in both 1:7 and 1:8 twist rates. To see what your gun will work with will require testing. I wouldn't invest in large quantities of long, heavy bullets until you've seen if your longer twist rate can stabilize them at subsonic velocities first. Good Luck!

So you think 300 blackout subsonic loads would work?

 

[Another_Kelley]

Cool Rifle Anthony! I've played a little with heavy (200gr) cast bullets in a Ruger M77 in 7.62x39. I was using Trail Boss, N120, and A1680. Trail Boss was the easiest to work with (and quietest suppressed) because it has such good case fill compared to other powders with reduced loads. Never could get what I would call acceptable accuracy with A1680 or N120 in regards to sub-sonic loads. A1680 was erratic when the case fill isn't above a certain level... velocity variations more pronounced.

Also worth a mention are Hornady's .312 XTP pistol bullets. At sub-sonic velocities, they still mushroom fabulously... and at 2000+ they behave like a varmint bullet. 100gr .312 XTP has been the most accurate 'odd-ball' bullet I've seen good unanticipated accuracy with. Tested them upwards of 2500fps with CfeBLK and they are still holding together for me.

 

[stoney1666]

tried some 220 gr x39 with 10.3 gr of 1680 and they dropped 8" at 100 yds. no trying for suppressed, just for fun.

 

[GeoDudeFlorida]

Hi Everyone,
I have been reloading for this rifle for a while and I'm getting a moderator for it soon, I really wanted to try some subsonic lead loads as I think it would be ideal at my local 50m range. Its a AIA bolt gun taking slightly modified AK mags, its 1:9.5 twist .311 barrel should stabilise most bullets under 1000fps.
View attachment 1181593
I've never downloaded rifle rounds before and I'm a little wary after seeing clouds of toilet roll flying down range and bent bolts!
Trying to avoid that I've done some searching and found lots of people talking about it, but cant find any specific load information.
Has any manufacturer ever publish subsonic rifle data?

Many thanks from across the pond

Anthony

The only thing I found that might be useful is the VV tables for 7.62x39. I’m sending you a screenshot but the app is free.

 

[MagnumPI_357]

Cool Rifle Anthony! I've played a little with heavy (200gr) cast bullets in a Ruger M77 in 7.62x39. I was using Trail Boss, N120, and A1680. Trail Boss was the easiest to work with (and quietest suppressed) because it has such good case fill compared to other powders with reduced loads. Never could get what I would call acceptable accuracy with A1680 or N120 in regards to sub-sonic loads. A1680 was erratic when the case fill isn't above a certain level... velocity variations more pronounced.

Also worth a mention are Hornady's .312 XTP pistol bullets. At sub-sonic velocities, they still mushroom fabulously... and at 2000+ they behave like a varmint bullet. 100gr .312 XTP has been the most accurate 'odd-ball' bullet I've seen good unanticipated accuracy with. Tested them upwards of 2500fps with CfeBLK and they are still holding together for me.

What load did you try with the N120?

I found numerous other posts saying 155gr lead with 4.5-5.5gr titegroup, but I'm dubious of pistol powder in rifle cases. I find 4.5gr of titegroup in my 45LC gives very erratic velocities, shame Tin Star still isnt in production and we cant get trailboss anymore

 

[n2omike]

4227 worked really well for me in 300 BO. VV120 was a good performer as well. Less luck with 2400, Lil Gun, H110, Enforcer. Those are the ones I can think of off the top of my head I tried. IMR 4227 was the clear winner among those. VV120 came in 2nd. This is with the Berrys 220 grain plated bullet. Your mileage may vary! 4227 would definitely be worth a try if you have it.

 

[EricBu]

Step 1: Slug barrel and verify....standard 7.62x39 uses .311 (.312 - .313 cast) bullets, but a good number of guns in the US use .308 (.309 to .310 cast) for obvious reasons. This is important for shooting cast, coated cast, and plated bullets subsonic. IE, if you have a .311 barrel a plated berry's .308 will be like throwing a hotdog down the hallway and you'll be looking at minute of barn. Using a cast (avoid w/ a can)or coated bullet in .309 in a .311 will likely result in the bullet not obturating at all, and not only gas cutting, but also causing a horrendous amount of leading in the barrel as well as the can (yes, a coated bullet will lead badly undersized).

Step 2: There is subsonic load data available for this round, with heavy bullets, and it's very close to 300 blk, but you'll have to work at finding it. The popularity of sub 7.62x39 dropped significantly when 300 BLK rose in popularity, and now there isn't many people doing it. Loaddata.com might have some, but mostly you'll have to search hard for it. It will be with the same powders as well, things like H110, RL7, Lil Gun, etc. Haunt the suppressor forums to find it.....it took years for sub 300 BLK data to be published anywhere, so you might have to work from scratch, in which case you can start with a 10% reduction off the START charge for 300 BLK or 300 Whisper subsonics of the same bullet/weight, but take a rod to the range with you because you may very well stick some bullets starting out. You could also download GRT (Gordon's Reloading Tool) and model what you want to do and see where it is pressure wise. You also must accept the risk of this, if you are new to reloading...developing your own load data from scratch is not the way to gain experience.

 

[EricBu]

What load did you try with the N120?

I found numerous other posts saying 155gr lead with 4.5-5.5gr titegroup, but I'm dubious of pistol powder in rifle cases. I find 4.5gr of titegroup in my 45LC gives very erratic velocities, shame Tin Star still isnt in production and we cant get trailboss anymore

Pistol powder is the goto for sub rifle shooting in a LOT of cases (see what I did there?), though TG is a little fast for this application IMHO. As an aside, 4.5 is a little light for 45 Colt. I run 5.7 under 250 RNFP in my 45 Colt loads, and they are ~ 1000 fps out of a Henry X w/ Hybrid 46 suppressor. 4.5 would be erratic I'd think, not enough pressure to obturate the bullet, not enough to expand case against chamber, probably pretty sooty too. I use a medium to heavy crimp in my 45 colts over TG.

 

[Another_Kelley]

What load did you try with the N120?

I found numerous other posts saying 155gr lead with 4.5-5.5gr titegroup, but I'm dubious of pistol powder in rifle cases. I find 4.5gr of titegroup in my 45LC gives very erratic velocities, shame Tin Star still isnt in production and we cant get trailboss anymore

I was using a powder coated 200gr Cast Lyman .314 pushed through a Lee .311 sizer. Started around 16gr of N120 and was in the neighborhood of 12-13gr before the super-sonic crack had subsided.

 

[chevrofreak]

I run a 220gr .309 Berry's spire point over 12.5gr of Accurate 1680 out of my Norinco MAK-90 (1 in 9.45") and they stabilize well, and actually have enough gas to cycle the action suppressed. You don't have to worry about cycling, so you could run a slightly faster burning powder and have a quieter result. VihtaVuori N120 might be something to look at .

 

[Swampman]

Has any manufacturer ever publish subsonic rifle data?

Hodgdon has some subsonic .308 Winchester loads with Titegroup and Trail Boss listed in their online data, but nothing in 7.62x39.

If gas gun function isn't an issue, my favorite powders for subsonic 7.62x39 are Red Dot for cast bullets and Trail Boss for jacketed.

 

[MagnumPI_357]

Pistol powder is the goto for sub rifle shooting in a LOT of cases (see what I did there?), though TG is a little fast for this application IMHO. As an aside, 4.5 is a little light for 45 Colt. I run 5.7 under 250 RNFP in my 45 Colt loads, and they are ~ 1000 fps out of a Henry X w/ Hybrid 46 suppressor. 4.5 would be erratic I'd think, not enough pressure to obturate the bullet, not enough to expand case against chamber, probably pretty sooty too. I use a medium to heavy crimp in my 45 colts over TG.

Your right there about the erratic 45lc, somewhere I shoot has a max muzzle velocity of a 1000fps so I have to at least try to stay under, They are for my long barrelled uberti SA. I'll try some more crimp as I dont run very much if that doesnt work I'll try heavier loads and see how I get on .

 

[N555]

I run 1:12 and 30cal spritzer bullets up to 190gr are stable subsonic with out a silencer but I never tested them with a silencer.

 

[MagnumPI_357]

I run 1:12 and 30cal spritzer bullets up to 190gr are stable subsonic with out a silencer but I never tested them with a silencer.

What load are you using?

 

[MagnumPI_357]

Step 1: Slug barrel and verify....standard 7.62x39 uses .311 (.312 - .313 cast) bullets, but a good number of guns in the US use .308 (.309 to .310 cast) for obvious reasons. This is important for shooting cast, coated cast, and plated bullets subsonic. IE, if you have a .311 barrel a plated berry's .308 will be like throwing a hotdog down the hallway and you'll be looking at minute of barn. Using a cast (avoid w/ a can)or coated bullet in .309 in a .311 will likely result in the bullet not obturating at all, and not only gas cutting, but also causing a horrendous amount of leading in the barrel as well as the can (yes, a coated bullet will lead badly undersized).

Step 2: There is subsonic load data available for this round, with heavy bullets, and it's very close to 300 blk, but you'll have to work at finding it. The popularity of sub 7.62x39 dropped significantly when 300 BLK rose in popularity, and now there isn't many people doing it. Loaddata.com might have some, but mostly you'll have to search hard for it. It will be with the same powders as well, things like H110, RL7, Lil Gun, etc. Haunt the suppressor forums to find it.....it took years for sub 300 BLK data to be published anywhere, so you might have to work from scratch, in which case you can start with a 10% reduction off the START charge for 300 BLK or 300 Whisper subsonics of the same bullet/weight, but take a rod to the range with you because you may very well stick some bullets starting out. You could also download GRT (Gordon's Reloading Tool) and model what you want to do and see where it is pressure wise. You also must accept the risk of this, if you are new to reloading...developing your own load data from scratch is not the way to gain experience.

Thanks for suggesting GRT, I'd never heard of it. Had a quick go with it last night and the results are interesting!

I don't like to bring up detonation, but I always had it in my head that small amounts of powder in a large case could cause it. Seeing that hodgdon say 8gr of titegroup in a 308case is okay it kind of destroys that idea. 5gr in a 7.62x39 gives the same load ration as 8gr in a 308.

 

[Another_Kelley]

I don't like to bring up detonation, but I always had it in my head that small amounts of powder in a large case could cause it.

It's my belief...that the detonations you speak of with, "large case capacity + small amounts of powder" - has a lot to do with the fact that when the primer goes off, the heat is allowed to enter the entire cavity of the bigger case all at once, and will flash ignite that fully exposed layer of powder, instead of the typical burn from one end to the other.....

 

[N555]

What load are you using?

Its for a 30-30.
What can you get for bullets?

 

[EricBu]

Thanks for suggesting GRT, I'd never heard of it. Had a quick go with it last night and the results are interesting!

I don't like to bring up detonation, but I always had it in my head that small amounts of powder in a large case could cause it. Seeing that hodgdon say 8gr of titegroup in a 308case is okay it kind of destroys that idea. 5gr in a 7.62x39 gives the same load ration as 8gr in a 308.

Detonation is more a individual or type of powder problem...and more likely to occur with small charges of really slow powder in a big case...H110 comes to mind. TG is kind of the GOTO for small charges in big cases in a LOT of applications...it excels in that application.

 

[MagnumPI_357]

Its for a 30-30.
What can you get for bullets?

I have some cast 155gr I'm going to load a couple at 4.0/4.5/5.0 and hopefully chrono them at the weekend.