Barrel installation "botchery"?
The carbine I built still isn't giving me the accuracy I'm expecting. I'm looking for 2-3 MOA but actual results are much worse. I initially thought the problem was a 16" Del-Ton barrel, standard hand guards, and the DPMS BCG that came with the upper, but that has been replaced with a 16" Daniel Defense barrel with LaRue rails and a BCM BCG--still on the DPMS upper.
I'm shooting my all factory ArmaLite rifle beside it as a control to make sure it isn't me. I get much better results out of the rifle. Both are being shot sandbagged from a bench with the same magnified optic (QD mount switching back and forth, paying attention to the group size and ignoring the shift in POA/POI between different ARs). Unfortunately, there are too many differences between the rifle and the carbine for me to say it's one thing or the other; examples, 1/9" vs 1/7" rifling, clamped gas block vs pinned front sight post, barrel profile, one all factory vs one built by me (this is probably the culprit heh), etc... At 25 yards, which should be very manageable, the control rifle is turning out < 1" groups (fine) and the custom build carbine is spreading them out to 2-3" groups. Remember: this is sandbagged from a bench.
I fully recognize Federal XM193 and XM855 isn't the most accurate ammunition in the world, but it should be tighter than 2-3" at 25 yards. I get the same results from both the rifle and the carbine whether I use XM193 or XM855.
I've reviewed the barrel installation procedure and I think I got it right. Zero loc-tite was applied during installation and the barrel nut took about 65 ft-lbs to get everything lined up, which I believe shouldn't be under nor over-torqued.
- Could there be something funky with the dimensions of the DPMS upper, especially as it pertains to how loosely the barrel fits into the receiver (I thought torquing the barrel nut would make that not matter a bit)?
- Is the Daniel Defense barrel, as tough and reliable as it is, just not going to give me the desired results?
- Am I just expecting something that is not reasonable from the carbine even though the ArmaLite rifle is yielding satisfaction?
- Something else I'm just not thinking of?
Will be happy to share any further details, but I think I brain-shat the right info... Thanks in advance!