7.62x39 susonic
 

First post so thought I'd better contribute something! Tried a 300/221 last year but couldn't get it to shoot and wasted 600 Sierra 240grners trying.

Was very dissappointed with first cold shot through a suppressor (will post a specific thread now i think of it)

Wish you guys had been up and running then !
Will no doubt discuss more about what went wrong...

Moved to the 7.62x39 in 3 different rifles and have had excellent results on goats and paper.

Keen to shere experiences with these catridges and especially some theories re suppressor design as had to do a lot of testing.

If I've realised anything it is that whatever problem I'm tackling here it has probably already been solved somewhere else !!

Curious
 

Email sent with questions...

I am VERY much interesting in hearing about this. I have had terrible luck w/my cold bore shots on my savage .308 and was considering .300 whisper using a model1sales 300 fireball upper on one of my AR lowers. If you can share any/all info you ahve... that would be VERY HELPFULL!!!

I see that there has not been very many replies to this thread. This is my first in here. I have had JDJ contender barrels in 300 whisper and I loved them. My question though is why not the 7.62x39? The more and more I think about it, why not just down load the Rusky? I am looking at building a new bolt gun and was going to buy the dies for my smith and have hime build me tha barrel and then got to thinking about the Rusky.

Is there any reason why this is not more common? Are there any hang ups or is it just a matter of timing. I know that there were not as many Ruskys in the country when the 300 was made popular and there was definately a stigma when it came to anything communist. Does any one have loading data for a 16" barrel and any suggestions for building up a bolt in a 7.62x39 subsonic? thanks in advance.

Excellent idea and there are a few loads posted here and there. As you said there is a stigma attached since its not "our" cartridge. Also there is the lack of bullet selection in .310 and the fact that barrel makers are a little hesitant to make a .308 barrel chambered for 7.62x39 because the first thing that will happen is somebodys gonna shoot hot factory (.310) cheap ammo in it and have problems. The 7.62x39 runs into the larger case capacity problem like the 308 win (though not as bad) with fast burning small kernel powders. Using low charges to get subsonic velocities with the pistol powders usually results in less than 50% full case density (possible secondary detonation) and gives wide velocity spreads. Think of it like this with a small charge in the case setting in the loading block all the powder is resting on the primer. Turn it on its side and the powder is all laying on the side of the case. Turn the cartridge nose down and now all the powder is around the bullet with an air gap between it and the primer. All these will have a different burn and the velocity will vary slightly so you want the case as full of powder as you can get with a small charge. This is where a high volume bulky powder that has a light charge weight is needed. For the 7.62x39 I use to use dupont "bulk" which had a charge weight of 5.5 grains per cc of volume and would make a nice subsonic load without fillers but unfortunately they stopped selling it in the 70's and supplies have dried up. Fortunately Trail Boss came out and it is appears to be an even better substitute since it has a charge weight of 4.6 grains per cc of volume and it really fills a case up. IMR hasn't released burning speed data yet but it is suppose to be close to red dot speed. I have been using it with 200 grain bullets and getting full cases with subsonic velocities (7.62x39) and am getting ready to load some with 125 gr speer tnt's. It is way to fast burning to cycle a gas gun but it looks good so far for bolt guns.

thanks for the reply here and for the guy that PMed me.while we are on the topic; what about the .30 carbine loaded subsonic and in a bolt gun? Wouldn't the smaller case take care fo some of the problems?

It's not that I do not like the .300 whisper; it's just that I am looking for an easier source of componants. Also if there is round that I can duplicate the 300 W ballistics with yet still have the ability to use factory loaded ammo. it would be a great benifit.

The 7.62x39 is very close and if you are going the custom barrel route just have them do a .308 bore 1:8 twist. .30 carbine won't take the heavy long taper bullets. I do agree about the components though and that is why I went with the 300 fireball instead. I kind of feel like a cheat but since I can barrel it as .308 1:8 twist and use resized .223 rem brass that was the way for me to go. I bought brass but am now setup to resize and trim brass under 5 seconds per piece so components shouldn't be a problem.

Just a little update since I mentioned using Trail Boss powder. Got to try some rounds in what the owner said was a match barrel and the bolt starts dragging with the 200 grainers at 960 fps so I see no way to use this with bullets over 200 grains if you are trying for the usual 1000 fps mark. This was at 9 grains of powder. The 125 gr FBHP fly very nicely at 1020 fps with 6 grains which is 1.3cc. I believe the powder burns a bit faster than what I was thinking.

just in case I'm talking about the 7.62x39 cartridge

pug, thanks for the information. Seeings how we are reloading anyhow. Have you tried running .311 in the .308 barrel. I realize that they have to be down loaded becasue of the increased pressures but it is possible.

Yes it is possible because at 50,000 psi you can swage all kinds of bullets down the barrel but as you mentioned pressures rise and are hard to calculate (at least for me). Also there is the fact that I see no need to use .311 bullets in a .308 barrel. There are more weights and styles in 308 and they are cheaper than .311 for the same weight. Now I have pushed quite a few .311 down a .310 bore but I am sure you know bullets are really lacking in .310. I have also had to drive (with a rod) quite a few .311s out of a .310 barrel because the drag was so much higher than expected for subsonic loads. I must point to the warnings in the bullet makers data where it says to use bullets only in the barrel they were designed for safety reasons but as you also said we are handloading....