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Posted: 3/2/2015 8:45:28 PM EDT
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Sorry if I'm beating a dead horse, but this is my first AR10 build. I recently assembled my mega maten and I'm having an issue with the bolt not closing on a live round. The barrel is a Rainier ultra match and I've tried two bolts (DPMS and AIM surplus). I tried head spacing both bolts prior to install they were both tight. I wasn't sure if I was doing it right. Here are some pics of what I'm talking about.
Bolt closes all the way with no round. 
this is the pic of the bolt with a 308 winchester round. 
Any ideas? Could I have gotten a defective barrel? Or defefective BCG's? |
| What color is your barrel extension? I know Rainier Arms offers a DPMS pattern (black extension) and an Armalite pattern (silver extension). I couldn't imagine both bolts are to blame, but stranger things have happened. Have you tried Rainier Arms in the industry forum? |
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So you're saying that both bolts DID headspace, but barely? And a round won't chamber? I know that 762 and 308 have different rim/brass thicknesses, that could be a factor. It shouldn't be, though. My guess is that your barrel extension or chamber is too damn tight. I've seen that before with "Ultramatch" stuff. Tolerances can be so tight that it borders on out-of-spec (or actually IS out of spec). The fact that you've tried two bolts and neither will close leads me to think it's the barrel. DPMS may not make the best stuff in the world but their 308 BCGs have been the go-to for ages with DPMS-compatible 308s. Contact Rainier and see what they say. Only bad AR15 bolt I've ever come across was a Rainier Ultramatch. (And the only out-of-spec lower I've ever had was a Spike's). ETA: DSTRBD asks a great question, are you sure you have the right barrel extension? -Stooxie |
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You take the extractor and ejector off of the bolt...
Then see if the bolt will "finger" close on one of these ten (10) : 
http://www.midwayusa.com/product/160060/ptg-match-headspace-gages-308-winchester-package-of-10?cm_vc=ProductFinding |
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Quoted:
The barrel extension is black. As far as removing the extractor... For the life of me, I could not not beat the roll pin out. I damaged a few roll pin punches trying. I've already started a post in Rainier Arm's forum. I'm just waiting to hear what they say. so teh ghey. 
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