He's doing more than that... He's claiming 500fps increase, accomplishing that by (for some strange reason) cutting a compound shoulder angle, rather than simply using the same neck/shoulder junction as the headspace reference as PO Ackley did to achieve the same goal, but most importantly, he's increasing operating pressure by 7,000psi. So he definitely isn't improving brass life with this plan - he'll be stretching case heads a lot faster with that higher pressure than any saving it might gain by less trimming.
So really, a guy willing to exceed SAAMI pressure standard by the logical interpolation that the AR-15 can withstand the bolt thrust of 52kpsi with the same case head when using 6.5 Grendel or 6 ARC (fair assumption, in my book), then if we believe the extra 500fps is attainable, then it's fair to expect we'd gain 350-400fps of the gain he's claiming simply by adding powder, changing powder, and running that higher operating pressure... Blowing the taper on a 7.62x39 case to a straight cylinder would increase the case capacity by 3.4grn H2O, a 9.5% internal capacity increase - extrapolating from Hodgdon, Hornady, and Nosler load data, commensurately increasing powder charge by 10% (which is NOT how we scale powder charge for improved rifle cases) would only yield ~150-200fps increase... I'd hesitate to believe that we'd actually get a 9.5% internal capacity gain with any feasible case design (aka, wouldn't blow out a straight cylider, we'd leave at least 10 thou taper, which only gives 7% increase), but it's really that increase in pressure which is doing the lion's share of the performance gain.
Ultimately, his cartridge shows 1) ANYONE with a 7.62x39 AR-15 can load 350fps faster than factory ammo by loading to known safe 52kpsi limit instead of throttling to 45kpsi SAAMI standard, and 2) Improving a cartridge by blowing out body taper and shoulder angle can add another 150fps... Not really Earth shattering news there...
I'll admit, I COULD be convinced it is wise to blow out the shoulder on a high pressure version of a cartridge so it can't be chambered into a weaker rifle design - such as adding a belt to 450 Marlin to preclude its use in Trapdoor 45-70's, but it would be more honest to describe that as the reason for blowing out, rather than trying to claim blowing out the compound angle shoulder as the reason for the 500fps gain.
When he describes the pigtail gas tube as increasing dwell time, I couldn't help but hope viewers understand this is absolute nonsense... Then he describes how an adjustable gas block operates, and states flipping the switch allows shooting the standard 45kpsi 7.62x39 ammo vs. shooting the 52kpsi wildcat... But then immediately his cohort asks, so you just flip the switch to shoot the rounds (repeating what he'd just said), and he flips his response and says, "no, you just flip that for shooting suppressors or not."... dingus...
The absolute nonsense of him shooting rapid fire and nearly falling over at 2:00 in his video, with his doofy hat on crooked just seals the deal for me. Even if the idea really did what it claims, I'd order a reamer and dies to make a straight 7.62x39 Improved, no silly compound angle, rename my version the "7.62 Notadumbass" and not send a penny to this dingus.
www.762yahweh.com
