I don't plan on getting either of these cartridges in the near future, but wonder how similar they might be ballistically. What advantage would the Whisper have, except perhaps being able to feed through a 223 magazine?

Hmmm...from Cartridge of the World, the whisper is designed to work with heavy bullets to achieve steady subsonic velocity for accuracy, combine the use of a silencer, to provide sound reduction(hence "Whisper"). I guess run-of-the-mill 7.62X39 can be loaded to do what a Whisper can do but the Whisper is made compatible with AR-15 so no change in magazine/bolt is required.
Hope this helps

Pyrotek

Mark, I'm sure you know that Colt has made some 7.62 x 39 AR's and that mags are available however the twist rate would probably be insufficient for the heavies as in the whisper. I have both a Colt, and a Wiseman custom mini Sako in 7.62 x 39 and the cartridge has proven itself on deer and Mtn Lion with great success. Bullet choice is most important of course. The dreaded 150 Nosler BT has been excellent at an initial velocity of 2375 ft/sec's. Also accuracy with this case has been superior.

308Sako: You've got exactly what I've been coveting in your 7.69x39 Sako. I assume it's built on the L-461? Sounds like a wonderful little deer and small game rifle.

Charles Daly has been promoting their Mini Mark X Mauser (actually a Zastava push feed) in 7.62x39, but none have yet been imported. That little gun wouldn't be up to the standards of your Sako, but for the price would be attractive.

Stonecreek, you wouldn't believe the accuracy. I called bill when I had a chance to shoot some 155 Palma's thru it, and grouped less than 1 inch at 200 plus yards. Wow, and no real recoil.

The 7.62x39 is a .311 diameter bullet, not a 308 like the whisper. There are not many heavy weight .311 bullets available, but plenty of 308s.

Dan

While the factory 7.62X39 ammo is all .311 for the SKS, most of the commercial guns chambered for the 7.62 have .308 bores. Both the Ruger 77 and the Mini 30 are both .308 bores. In addition RCBS dies (and others perhaps) are shipped with both a .311 and a .308 expanded balls. Makes feeding your toy easy.

I also used to own a 7.62X39 bolt but mine was on the Sako A 1 action. The rifle was much the same as 308sako's sounds I however used the 110 gr. Barnes X at 2700 fps. Great little killer and did it shoot. I think I'll have to do this again but next time on the 75 action.

Gabe

When loaded with the same weight bullet, they appear to give almost identical velocities. The only advantage I see is that the Whisper is based off the .223 case, so bolt actions would be far more easy to find to work on than one with the 7.62 bolt face.