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Posted: 6/22/2005 3:33:03 PM EDT
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I got a free 20" h-bar barrel for a member here and i stuck it on a upper that i had and i put a dummy round in the chamber and closed the bolt and went to pull back the bolt and the round stayed in the chamber. The bolt is an RRA bolt and its new it runs perfectly in my M4grey. My only idea is the chamber is to deap or the locking lugs are worn down. and i dont own any headspacing gages so there most likly not much i can do if the chamber is to deep. Thanks for any input and info |
This is my biggest fear about assembling an upper from parts. Sure, they are all made to work together.  "Mil Spec" means nothing.The proper way to headspace a rifle is have the bolt of that rifle push the chamber reamer just until the bolt closes, and then check with a complete set of gauges, and measure fired brass too with a Mo's Gauge (spelling?). This is what I do when headspacing an M1A or Garand. I prefer barrels with short chambers. Chrome lined barrels can be cut, BUT it is not easy; also, sometimes, the chrome is cut all the way through. All this assembling of parts that are, supposedly, made to close tolerances, leaves too much in question. I don't know how to fix your problem. Measure the headspace. If it is too large, try another bolt, until one fits. |
| It's possible that your dummy round has the shoulder pushed back to far. I've got 3 guages. A .223 Go, a .223 No Go and a GI 5.56mm field. The only one that really matters is the Field guage. If it will swallow that then you have excessive headspace. It's quite rare to have a headspace problem. I've done about 20 builds over the last 13 years for myself and friends and never had a problem. |
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