Ideas for subsonic 7.62x39?

[Monkeyman]

I need to load some subsonic 7.62x39. The first issue is bullets; I have two guns I need to load for, an AK47 (presumably with a bore close to .311") and a Contender with a .308" bore. Since the AK is a bullet hose anyway I think I can concentrate on .308" bullets, preferably softpoint and maybe around 200gr to 220gr. The brass is Federal American Eagle, it's my blasting ammo.

So, I need some thoughts on bullets and powder to achieve 1050fps from a 10" barrel. My Contender barrel is a rechambered .300 Whisper, I think twist is 1:7 so I should be OK with 220gr bullet stability. Max range will be 100yds.

I already have Bullseye, Red Dot and Blue Dot as well as H4227. Should I be looking for data for light .44mag and similar handgun loads? Or maybe just use .300 Whisper loads and hope the extra case volume doesn't matter?

Please feel free to theorise as much as possible.

[Rocky Raab]

You'd be on the right track with existing Whisper loads. You might have to bump them up a tad, but that only means that Whisper loads are perfect as starting combinations.

I also agree that the bore diameter difference probably won't matter that much.

Got any greenies, lately?

[Monkeyman]

Thanks Rocky

Got these two on a golf estate recently, 50yd headshots with suppressed 77/22 and CCI0056 SS HP. Seems they were bothering the guests, a troop of about 40. I need to go back a few more times.

I'll go searching for Whisper loads, if you come accross any please post them here. The contender barrel also has a problem ejecting, seems the ejector is bent. Have you had that happen to a Contender before?

[Rocky Raab]

Yes, I have. The problem occurs when you get a sticky case (after firing) and open the barrel. The extractor wants to move the stuck case, but can't. When you push down harder on the barrel to open it, the short side of the "L" on the extractor gets bent inwards - it is stuck under the extractor groove of the rimless case. Eventually, your arm wins and the extractor loses. In worst events, the extractor even slip out from under the case.

If you look at the extractor with no round inserted, you'll see the bend.

You can carefully bend it back, but it's weakened forever. Oddly, this seems to happen most often (almost exclusively) with rimless cases. I think the cut needed to install the spring for the rimless style extractor is part or most of the reason. Rimless extractor are simply weaker due to that cut.

[Rocky Raab]

Load data for 300 Whisper, all with 220-gr bullets. altered 221 Fireball cases and Rem 7 1/2 primers, ALL give sub-sonic speed:

AA5 - 7.5 grs
AA7 - 10.5
AA9- 8.5
1680 - 10.3
2015 - 12.0
(I cannot understand the charge weight for AA7, but that powder has always been a conundrum to me - RR)

H110 - 9.0
4227 - 9.2
335 - 13.8

Edit to add: Here's the webpage source of this data
http://www.quarterbore.com/300whisper/

[Lone Star]

I would strongly recommend against using fillers in any semi-auto cartridge. The violent action of these arms can cause the filler to shift with potentially disasterous effects. With the powders recommended, particularly the handgun and flake shotgun powders, no filler is needed particuilarly since the long 220-grain bullet must be deeply inserted into the case, safely taking up plenty of space without a filler. I've shot many sub-sonic loads out of my .30 Herrett (limited to 150-grain flat based bullets due to its slow 14" twist) using BlueDot with no filler and great performance. The Herrett has a very similar case capacity to the AK round.

Fillers are seldom recommended for any reduced loads anymore due to the potential for chamber ringing and filler shifting. Lyman, who for decades recommeded fillers in larger cases like the .45-70, no longer does so.

More .300 data:
http://www.accuratereloading.com/300whisper.html