I need to ask AAC if their velocity spec is based on CIP or SAAMI, as SAAMI does have a 5K psi lower limit and could explain the slower velocities. AAC does rate from a 20" barrel. Accuracy was better than most typical FMJ/HP I'm used to testing in this caliber. My lot size is small, but I did have one pierced primer in the SKS. I've had pierced primers before in brass case 7.62x39mm, so likely a primer cup tolerance needs to be looked at. No noticeable excessive muzzle flash from their powder choice. No cracked cases or issues related to the cases themselves.
As far as the gel results go, we had expansion from all of our typical barrel lengths. You can effectively apply what you see from the 10", as to what you would get at 50-75 yards when fired from a 16". I have confirmed with AAC that this bullet is a Hornady SST, and Hornady is doing all of AAC's in house bullets. I will try and work on the FMJ test next. I was sent this ammo slightly before production started to review.
7.62x39mm, 123gr Sabre Blade Black Tip, America's Ammunition Company (AAC)
7.62x39mm, 123gr Sabre Blade Black Tip, America's Ammunition Company by
Buffman RANGE, on Flickr