Last week, I assembled one of the recent Colt M16A1 kits currently for sale from Century.
The parts are almost new and the barrel is an aftermarket 1/9 barrel. The barrel has no manufacturer's mark, but the word on the street is that they're from Green Mountain.
When I went to check the headspace, I found that the bolt won't close on a Clymer "No-Go" gauge (from Bushmaster), but also won't close on the "Go" or an unfired M193 cartridge case (bullet pulled). The gauges are marked 5.56/.223 REM and I tested with the extractor and ejector removed from the bolt. I ordered another barrel of the same make from Apex Gun Parts, and had the same result.
Is it correct that there's no fix that I can do? Has anyone had the same experience with the barrel extensions on these new barrels being set too tight? The bolt in the kit is new; is there any use in trying a used bolt?
Here are some photos to illustrate my results.