08-18-2011, 06:44 PM
The only things I've really seen break on M4's & AR's as far as operating parts go is bolts, and that is on guns run through extreme schedules. While I've heard of Grendel bolts breaking, I haven't seen it yet. I have broken non-MPI bolts on AR's after over 10,000 rounds through the gun within a year. I cracked the handguards on my M16A2 when Clinton got re-elected in 1996 while I was in the field on the DMZ in Korea, but I don't think you're talking about that...
It's always good to have spare bolts on hand, that have the exact same bolt face depth. You should also change your ejector and extractor springs every 2000-4000 rounds, and look at the bolt gas rings around then as well. After about 5k of high volume, gas rings can erode, and cause you to lose your gas seal, leading to short-stroking. Recoil springs are also supposed to be changed at somewhere between 5000 & 7000 rounds, depending on how they measure in length, or if they become weak. Most soldiers don't realize what parts are periodically changed in their weapons because it is armorer-level maintenance. As a civilian, one needs to assume these armorer-level duties oneself. The AR is probably the easiest service rifle to maintain, without any real gun-smithing skills, so only a few basic tools are necessary.
It's always good to have spare bolts on hand, that have the exact same bolt face depth. You should also change your ejector and extractor springs every 2000-4000 rounds, and look at the bolt gas rings around then as well. After about 5k of high volume, gas rings can erode, and cause you to lose your gas seal, leading to short-stroking. Recoil springs are also supposed to be changed at somewhere between 5000 & 7000 rounds, depending on how they measure in length, or if they become weak. Most soldiers don't realize what parts are periodically changed in their weapons because it is armorer-level maintenance. As a civilian, one needs to assume these armorer-level duties oneself. The AR is probably the easiest service rifle to maintain, without any real gun-smithing skills, so only a few basic tools are necessary.