Teri Anne's post was very detailed and absolutely excellent!
I recently had DPMS AR in 5.56 NATO that I had trouble getting any kind of accuracy with it. Three inch groups at 100 yards was common even after adding a Timney aftermarket trigger and trying a number of different handloads and bullets. I'd gotten a Teslong borescope for the prior Christmas & found the bore to have a lot of copper fouling in it! I finally scrubbed the bore with JB paste & Kroil down to bare metal and put a lot of effort and sweat into it! The first trip to the range gave me 3/4 inch groups with several loads!
I'm a hunter and also a handloader but I often put my deer rifle away for 9 or 10 months between shooting it! I once had a deer hunting rifle that had previously given me 1 inch 3 shot groups at 100 yards with it's favorite loads! I cleaned it as best I knew at the time after hunting season, put it in the safe and after about 10 monrths, took it to the range to make sure it was still sighted in! I couldn't get groups under about 2 or 2 1/2 inches!
It was a Featherweight M-70 Winchester in 270 Win. and really liked the rifle but I eventually sold it because of the accuracy issues! Now I wonder if that barrel simply needed scrubbed down to bare metal?
