Hey Gunnutz, I'm having a bit of a chuckle over the XCR parts kit request, concerning a gun with 200 rounds through it
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Fwiw, in my experience with my XCR, at a little over 18,000 rounds through it, the only parts you may want on hand, are springs and maybe a recoil buffer.
My hammer spring broke, the replacement was upgraded to the x39 surplus spring. Was always a x39 upper/rifle but the hammer spring was the same as my friends .223 rifle. The upgraded spring has lasted over 10,000 rounds.
My recoil buffer is original, and still looks new.
The day I bought the gun, I took it out with the sole purpose of figuring things out, i.e. the gas setting. That's what the day was dedicated to, and it took all of 2 hours to break the gun in and learn that 1 was too low and 3 gave me trigger slap. It ran on 2 for thousands of rounds, it's now on 1. That said, it's not a set it and forget it, system.
The easiest way to learn the gun, is to induce failures as well as inducing what can be obnoxious trigger slap. Try the gun on 4, 3, 2, 1, and even S. Figure out what causes what. It's easier to do it on your terms than waiting for the gun to stop cycling, then wondering why. Or wondering why the buffer is torn.
Ambient temp shouldn't affect the gas system, different brands of ammo will.
Learn the gun, so when it talks to you, you know what it's saying.