Hi all, I bought a 300 wisper 10bbl and sent it off to SSK to be reamed to 30x39. My intent was to shoot lots of surplus 7.62x39 ammo in it. I'm getting sticky extraction. Could it be the steel cases, mostly Russian Hollow points, or too high of pressure? The Russian hollow points seem to work really well on ground squirells. Plus they are cheaper than I can reload for.
any thoughts?

If you are shooting this in a Contender, you are asking for trouble -- and I'm surprised JD didn't lecture you before letting the barrel go. The oversized bullets, coupled with the high breech pressure, combine to create enough backthrust to seriously damage a Contender frame.

If you are shooting and Encore, the frame is beefier and stronger, but the same combination I mentioned earlier, not to mention the steel cases, will bring this problem about.

Shooting .311-312 bullets through a .308 bore is seldom a good idea...

Okay, I already have a 30-30 and 309JDJ. What would be another good caliber that I could rechamber this bbl to?

Heck ya got it, you have already paid for the barrel and a rechamber job , just load for it with prudent loads and 0.308" bullets. Way back when NRA convention was in Nashville, the TC reps told me that the Contender barrel would NEVER be chambered for the 7.62X39 because some lots of "military" ammo were up to 40 percent above SAAMI standard for pressure.
So you gots a rimless 30 Herrett and may even be able to coax a bit more performance from it.

Case capacity is still case capacity, pressure is pressure, and pressure and capacity control all the rest of the results!

LouisB

Just my opinion of course . . .but worth all you paid for it!

I have always wondered what the Fascination with the 7.62x39 is? We already have the 30 Herret which is pretty much the same round. And I would think of one wants to UP the horepower a little maybe form some cases with 375 brass.

The danger of the 7.62x39 is the .311 or .312 bullet in a .308 bore when using military Ammo.
Maybe it is the CHEAP CHINESE ammo we could buy to help fund more weapons for the chinese army?

Fireball

.30x39 means .30 caliber bullets, not .310" & larger, which also means you must reload, which also means the monkey is on your back to produce ammo that is safe to shoot.

If it were intended for 7.62x39 standard ammo, I am sure SSK would have so marked it as such.

Way back in the early '90s I improved the 7.62x 39 to the Ackley type configuration to increase case volume and decrease pressure.... all in an attempt to make shooting surplus ammo possible in the then new .32-20 and .32 H&R Mag. barrels TC was bringing out, which, btw use .311-.312" bullets in the TC factory .308" groove diameter barrels. Also, anyone with info to the contrary, correct me, but I am 99% certain the Ruger Mini-30s had .308" groove diameter barrels. So the act of shooting .310" bullets in a .308" barrel is not so far out as suggested.

Even long throating with a .311" diameter throat in the TC factory barrels did not work. Still too much pressure in the 8 equal land and groove factory barrels.

I had made a number of standard 7.62x39 barrels in both .308 groove diameter and larger groove diameters up to .312." In standard rifling types where the riflings are narrow, they worked.... marginal, but they worked.

But in the factory barrels with the wide riflings, it was a "no-go" no matter how I chambered and throated. The factory barrels simply ran too much pressure, which can only be attributed to the amount of bullet metal displaced by the unusually large surface area (more correctly, volume) of the wide factory riflings.

In regard to shooting .310" bullets through .308" groove diameter barrels, it is the throat that runs the pressure up if it is not large enough for the larger bullets. Ie., throat a .308" groove diameter barrel that has narrow rifling with a .310" or larger throat diameter, and you can shoot the standard 7.62s in Contenders.

But since it is simply too, too close to the ragged edge, even though I have done it a number of times, I do not recommend it, nor will I normally do it. And I certainly am convinced to NOT do it at all in the equal land and groove factory barrels.

If you want to shoot surplus ammo, stick with the Encore.

BTW, the early work I did with the 7.62x39 in Contenders was in cooperation with an Army EOD technician from the Dugway/Tooele area Army Depot and involved many different types of surplus ammo. Some of it is in fact hotter 'n a firecracker, but neither Mick nor myself stretched any frames that I can recall.

On the other hand, commercial WINCHESTER, ie. SAAMI spec., FRACTORY ammo would blow primer pockets when fired through even the improved 7.62x39 chambers with .311" throats. And these should not have been steel jacket bullets either.

When the .310" factory bullets were pulled and the same weigh .308" bullets substituted in the same case with the same powder charge, pressures were fine. But the combination of .310" bullet and the wide factory rifling just did not work.

BTW, the Improved 7.62 case with .308" bullets is a neat round, ala .30 PPC except for the sharper 40 degree shoulder. Except for the lack of a rim, it is a more expedient version of a .30 Herrett, requiring only fireforming with new commercial brass to make cases.

Mike