02-01-2023, 10:37 PM
Upper received back from gunsmith today. I noticed that the BC was changed as per my request. I then weighed the BCG and the BCG from the semi auto version Colt lower. There was a 1 oz. difference, the Colt was the lighter of the two, as expected. I added a little more lube to the BCG ( the heavier one) that came with the Grendel upper and proceeded to fire and function test. I did take both BC's with me, just in case.
Loaded one round in the mag and fired. Proper ejection and bolt locked back correctly. Tested 3 more shots that way, all locking back correctly on the bolt. Loaded 3 rounds for semi auto fire, knowing that it would function correctly since it locked back on an empty mag as it should. It functioned as expected feeding reliably and locking back on the bolt when empty.
Nothing wrong with the Colt Sporter lower, or the 5 oz rifle buffer in the A2 stock assembly. Apparently the issue was caused by a faulty BC. The gas chamber didn't look correct to me upon inspection, having an area about mid length of the chamber where material appeared torn out ( galled depression) rather than machined.
Called the smith and relayed my results and satisfaction with returned upper. The BC that was sent back with the upper was the one he tested with as well.
In conclusion, I now have what I expected to get initially, a fully functioning Grendel upper that functions with the lowers I have. Now to continue with load development and get some shooting in, on paper and maybe some coyotes too!
Thanks to all that responded to my original post, I appreciated the help.
Loaded one round in the mag and fired. Proper ejection and bolt locked back correctly. Tested 3 more shots that way, all locking back correctly on the bolt. Loaded 3 rounds for semi auto fire, knowing that it would function correctly since it locked back on an empty mag as it should. It functioned as expected feeding reliably and locking back on the bolt when empty.
Nothing wrong with the Colt Sporter lower, or the 5 oz rifle buffer in the A2 stock assembly. Apparently the issue was caused by a faulty BC. The gas chamber didn't look correct to me upon inspection, having an area about mid length of the chamber where material appeared torn out ( galled depression) rather than machined.
Called the smith and relayed my results and satisfaction with returned upper. The BC that was sent back with the upper was the one he tested with as well.
In conclusion, I now have what I expected to get initially, a fully functioning Grendel upper that functions with the lowers I have. Now to continue with load development and get some shooting in, on paper and maybe some coyotes too!
Thanks to all that responded to my original post, I appreciated the help.