It was nice and snug. There's an angled shoulder along the outer tube that basically works like a compression mount. Threads were nice and clean, so it spins on smoothly and just snugs up on the shoulder. They also offer a 5.56 end cap, if you're into that kind of thing. The most impressive part was the mount. VERY solid. It basically interfaces with two separate shoulders, pulling the can solidly onto the mount, with compression from the front and rear of the mount. After you thread it down onto the front shoulder, it has a elliptical ring that works sort of like the ASR, but better. When you tighten the locking ring, it squeezes a second shoulder on the rear of the mount when it locks down. It and the Deadair mounts are by far the best on the market right now.
Normal cook offs due to the rate of fire. But it did a good job of demonstrating that the modular design would outperform the capabilities of an AR.
