Beautiful but out of spec
I've been building and shooting ARs for over 30 years. I can troublsehoot nearly all problems and have the tools, gauges, and drawings to make repairs and even predict issues. Sometimes a tolerance stack up can work to a builder's advantage if you have the parts to swap around, but often it will ruin a build if too large.
The design and appearance of the carrier is excellent. It's really stunning in the grey DLC coating, reminding me of a dull chrome finish--not blingy but still eye-catching. The finish is smooth and even. The only visual issue was the gas key staking looking like it was done with a square punch (def not a MOACKS). It was uneven, too, and raised sharp burrs. Not impressed by that. The OACKS screws are first class but only a proper staking can fully utilize their innovation.
With this carrier I used a brand-new JP Enterprises enhanced bolt, cam pin, firing pin and retainer. This is one of the most impressive bolt kits I've ever seen and gauged. Flawless fit and finish; worth the money. After BCG assembly I checked headspace and headed to my range. I must note that the feel of the gas ring in the new SA carrier was quite rough but not unusual for a brand-new build. However, JP uses a very relaxed one piece ring and it passed the standing test. A bit odd IME.
Loaded one M193 round for lockback test. It failed and recoil was suprisingly soft. Tried a few more times, same thing. Tried a full mag and had short stroking. I swapped the A5H2 for a A5H0 and M193 finally locked back. Tried Wolf .223 and, again, no lockback. Swapped the Sprinco green spring for a (used) polished JP rifle spring and it actually locked back consistently (it's an OLD spring). It should be noted that the gas port on my test barrel cycles all ammo 100% with hot 5.56 heading to 2PM and weak .223 going to 4-430PM. Verdict: Something is wrong. Also note that this carrier is about 2 ounces lighter than a standard M-16 carrier.
Upon close examination I found that the bolt tail run/bore was way too big causing a significant gas leak and hammering the FP retainer in short order (and lot's of fouling in the fire control area). All other dims were in spec (bolt run, gas key run, gas key bore). Unfortunately, a problem like this cannot be fixed unless you can find a bolt with an out-of-spec tail.
