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Okay, it seems the problem is not solved. I put 693 rounds through the rifle in Kyle Defoor's class last weekend. Gun ran like a champ. Slow fire for distance, mag dumps, etc.
Take the rifle down to clean it and... (drum roll please) the bolt carrier collapses on the bolt as if there were no rings. The ring (McFarland) appears compressed.
I'd love to hear some thoughts/suggestions.
Thanks!
One of my kit builds ate gas rings. Went through three sets of rings in the first couple hundred rounds. Got a Mcfarland ring from Fulton Armory and have put about 500-600 rounds through it with no further problems. Since then, all my AR's have Mcfarlands. Some pass the carrier weight test and some don't, but I have no problems.
Hmm. Here's two reports where McFarland rings failed the standard test, but users report their guns still run.
Do McFarland rings need a different standard for testing whether they're worn out? My gut and engineering judgement both say "rings is rings. don't cut McFarland any slack". But then, why would McFarlands keep a gun running while loose, whereas loose 3-piece rings are known to cause short stroking?
IraqGunz, I am super curious as to whether your large sample of McFarland rings passed or failed the "standard test" (i.e. does the bolt carrier collapse down onto the bolt when you set the assembly down on the bolt face). Also, if they "fail" the test, how'd you justify running them anyway?
Last edited by kartoffel; 01-27-12 at 21:57.
Oh no, not another lube thread! Read this first: Lubrication 101.
That's correct. Same way the Army taught me in 1990. I have seen some folks do the opposite where they hold the bolt to see of the carrier falls off.
I'm tempted to just keep shooting it until it starts to choke and see how long that is. The rings aren't expensive, but I don't think I should need to replace them every 500 rds.
Kartoffel, the gun did this the first time with the standard 3 gas rings. It wouldn't pass the field test, but it continued to run without a hiccup so I don't think it's a McFarland thing. I am wondering if it's a Young Mfg thing though...
Last edited by El Cid; 01-28-12 at 11:35.
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Kartoffel,
When I was doing the overhaul of Bushies I did a number of things.
1. Checked and staked carrier key.
2. Staked castle nut.
3. Reamed chamber with M-guns reamer.
4. Replaced extractor spring and insert.
5. Replaced gas rings.
In every case the gas rings ALWAYS passed the test. I never had any of the McFarlands fail and should they have, they would have been replaced.
Owner/Instructor at Semper Paratus Arms
Facebook: https://www.facebook.com/SemperParatusArms/
Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/
M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141
Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com
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