I purchased a CZ527 Carbine in 7.62x39 with the intent of converting it to a 6mm PPC or 6.5 Grendel, but found that it was capable of 5 shot ~MOA accuracy at 100 yards with handloads in a nice handy package. I had concerns about the construction of the 123 grain bullets, so I started experimenting with loads using the 150 gr. Sierra .311" diameter bullet.

RL-7 delivered good accuracy and reasonable velocity (2200-2300 fps), but the powder still seemed slightly slow for the application. I next tried IMR 4198(not SC) and it's bulkier than RL-7 so even though it was slightly faster burning, the practical limit as what you could get into a case was about 2 grains less than RL-7. I tried AA1680 and the accuracy was less than that obtained with RL-7 and IMR 4198.

I was about to try AA2015, when I remembered the pound of Lil'gun I had tucked away for my 218 Mashburn Bee. I couldn't find any loading data for Lil'Gun for the 7.62x39mm, let alone with 150 grain bullets. The 30 Herrett has a slightly smaller case capacity than the 7.62x39, so I stated off by using WW296 data with 150 grain bullets as a starting point.

My stash of 150 grain .311" in bullets was dwindling, so I decided to use 150gr. 308" diameter R-P 30-30 bullets for the test loads. While not delivering the best in accuracy department, the sub-diameter bullets still proved capable of delivering ~2MOA accuracy during previous loading sessions.

Here are the results:

19.0 gr. 2115 fps
20.0 gr. 2216 fps
21.0 gr. 2292 fps
22.0 gr. 2390 fps
23.0 gr. 2437 fps
24.0 gr. 2502 fps

I stopped at the 24.0 gr. load as 2500 fps was more than I had hoped to achieve. Below is a link to the case heads of the 24.0 gr. loads. The brass was previously fired in a semi-auto, which is why the case heads are dinged up a bit.

http://www.hunt101.com/img/463405.jpg

While "reading" primers is less than an exact science when it comes to operational pressures, these still look like they have plenty of radius left.

John in Oregon

Looks to me as though the primers may be "Cratered" a bit.

2500fps out of a 7.62x39 with a 150gr bullet?? Seems "Hot" to me. Thats gettin close to 30-40 Krag and 300 Sav velocities in that tiny little round.

Good Luck and Be Safe.

.

John, I was all interested in trying Lil Gun in my 2 - 7.62 X 39's, one a Sako bolt and the other a Colt AR. It was to shoot a Hornady V-Max 110 grain .308 bullet as I believe both barrels I have are .308 diameter. I ran into excessive pressure with 23 grains and the 110 V-Max. velocity was 2700 ft/secs though. The exact charge is memory and faulty, I'd have to try to find some old posts. I could not get over the fact that for me this powder wouldn't do miracles! It looks like a natural from the .22 hornet loadings and other applications. I would also mention that it is very primer sensitive in the .22 hornet.

I think you are on thin ice with these loads, please be careful.

Now off to try and find my data.

No luck serching archives... my inabilities. There are other postings dealing with reloading this fine cartridge. I have found that AA 1680 and V V 130 to be very 7.62 friendly. R#7 is also good, as is IMR 4198. Speed = pressure, can't have one without the other.

I agree with your pressure concerns. I think the sub-diameter bullets helped keep the pressures down in these tests. The bolt lift was normal as well, but as we both know by the time this indicatior appears pressures are way too high.

I'm going to start out low again, but his time using .311" bullets and Federal 205 primers, as the Federal primers tend to flatten out more as the pressure increases.

John in Oregon

I took the cases that were loaded with the 24.0 grain load and deprimed them in an arbor press and seated fresh Rem 7 1/2 primers in the cases, and found the primer pockets to still be tight. That's still not conclusive that the pressures were reasonable, but had they been opened up it would have confirmed suspicions that the pressures were excessive.

I'm wondering if the burn profile of the powder is highly progressive and the bore volume expands at a rate that keeps the pressures reasonable in this instance.

Here's a comparison of the Lil'gun .308"
vs. .311" bullet results:

150 grain .308" bullet
19.0 gr. 2115 fps
20.0 gr. 2216 fps
21.0 gr. 2292 fps
22.0 gr. 2390 fps
23.0 gr. 2437 fps
24.0 gr. 2502 fps

150 gr. .311 Bullet
19.0 gr. 2070 fps
20.0 gr. 2153 fps

I didn't load any rounds using the .311" bullet beyond 20.0 gr. but it was clear that the Federal primers were flattened to a greater extent as compared to the loads using Remington 7 1/2 primers and .308" bullets.

Based on what I saw, no way would I attempt to use 24.0 gr. of Lil'gun with the .311" bullets.

Johnly, Thanks for continuing the LilGun and 7.62 saga. It would appear that it is one sensitive son of a gun to work with in certain applications. I noted in the .22 hornet that it was extremely sensitive to which primer was used, and that a lesser spark kept pressures down and velocities up. It might be very interesting to try some small pistol magnum primers and the R-P cases with loads of an already know result???

I've used Federal 100 SP primers in 22 Hornet and 218 Mashburn Bee loads and they tend to pierce when you push the pressure up to normal rifle pressures. I have some Remington 5 1/2 and 6 1/2 primers that might be worth a try, but the accuracy level of the last round of Lil'Gun loads wasn't all the impressive. 26.5 gr. of RL-7 and a 150 grain .311 bullets shoots exceptionally well and churns up 2200 fps, 28.0 gr. of RL-7 with the 130 gr. Norma bullet delivers equally fine accuracy while delivering 2340 fps. I also fired some Norinco 123gr. FMJ as a velocity check, which measured 2290 fps and 3"+ groups.

I'll keep working on the Lil'gun loads, but I'm going to spend more effort exploring AA2015 and 4198SC (when I find some).

Johnly, I agree that the small pistol primers would not handle the pressure, but the magnum ones should as they are for the likes of the.357 etc.

I also agree that one as to be happy with reasonable results of normal powders!

That is why I have stuck with Vita Vourhi 130 and 133 or AA 1680.