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Posted: 4/15/2011 4:05:24 PM EDT
| I just recieved two uppers today. One 5.56 and one 6.8 SPC. I have yet to pick up any 6.8 ammo, so I don't really know the dimensions. I pulled the BCG's out of the two rifles, and there does not seem to be any size difference between the two bolts. The battery is dead in my digital caliper, so I can't really check it that way. I placed an empty 5.56 casing on each bolt face, and can't see a difference. I assume that I need to be making a phone call Monday morning. |
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There would be about an 1/8" gap with a 5.56 round in a 6.8 bolt. I can see a difference looking at mine just on bore size alone. Another visual indication is on the 5.56 the ejector has it's own groove in the bolt wall but the 6.8 ejector is about 1/32-1/16" away from the wall so the inner bore of the face is perfectly round except for the extractor claw. ETA: After looking at the 6.8 again there may be a very slight groove for the ejector.
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