Disclaimer: I want a LWRC 308 and a XCR-M, so don't think this an AR-piston hate post.
I like the big AK like bolts of the XCR, seems impossible to break. The POF bolts are the same AR bolts that are prone to breakage at the cam pin hole and little lugs that are known to get sheared off with heavy usage.
I have PDF document from Crane (dated 2006) weapons report I got off the web detailing the shortcomings of the AR. Basically it said M4 bolts that seen hard usage (mostly in full auto) should be canned in the bin at the 3,000 round point. M4 bolts that shot mostly in semi-auto, should be canned at the 10,000 round point. Remember these are milspec Colt bolts the Crane report is referring to and not civi Bushmaster bolts. I hear Internet Rangers tell me they have 20,000 rounds through one Colt M4 bolt, I am not hear to argue with them, I am only stating what the Crane Reports say.
Those of you want to see this Crane PDF, PM me your email and I'll send it to you.
Basically the issue with a DI system is heat and high pressure, take these away and the AR system is cured! I hear from the internet, LWRC, HK, and POF that these Colt AR/M4 bolts will last a lot longer in a Piston AR (such as LWRC or POF), because the system just runs a lot cooler and most of the high pressure gas escapes off before it reaches the bolt. Though this makes totol sense to me, you still have to ask....
- Was it not the high pressure gas is what enables DI's AR's to reliably cycle, even if full auto? I am sure Stoner was no dummy, and if he really believed the AR system needed a piston, he would have put one in.
- If the piston of the these piston-AR's is taking the brunt of the force, would that not mean these little pistons are now prone to failure because of these hot and high pressure gas? Are we not taking a reliable and simple system of a DI AR only to make it more complicated? Have you seen these pistons? They are little (and remember they have to be in order to use them with the existing AR system). The XCR piston is nice and beefy, enough where you can wack someone over the head with one, and put it back in your XCR and you know your gun will still reliably work.
I also still doubt these same M4 bolts will last that much longer in a piston AR system, it is still the same bolt with little iddy biddy lugs. I betcha if I accidently dropped an AR bolt at just the right angle enough times on cement, these lugs will eventually break off, so no hot gas and high pressure needed! Look at the lugs of an AK an XCR and you can see they are 100 times more beefier and there is no way they will break off by dropping them on the cement.
Another Disclaimer: This report was given by a gun ethusiast who enjoys this hobby of guns, but has no gun back ground whatsoever (other than humping one while in the Army). So flame away! I look forward to your flames. ;D