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Posted: 8/26/2006 3:46:35 PM EDT
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I finally got around to sighting in my DPMS AP-4 Carbine today. It seemed to take forever to get the rifle to even start shooting in any kind of a group. After 2 1/2 hours and 100 rounds of PMC 55 grain FMJ, I was shooting 3 inch groups at 50 yards, using the iron sights and a bench rest under the handguard (I know, it's terrible accuracy, but I'll work on that). In order to get the rifle sighted in to this point, my windage was adjusted almost completely to the left. I feel there is something wrong, that the windage shouldn't be adjusted that far to the left. I've searched throughout this site for similar inquiries, but the results were limited. Some responses to those other inquiries recommended adjusting the FSB and re-sighting. I have no idea what this means. Is there something wrong that my windage requires to be adjusted that far to the left? How can I fix/correct it? Thanks, Gunner |
| Sorry to hear you were having a hard time... 3" at 50 yards does seem to be a problem, and having to crank the windage nearly all the way seems like it also may be a problem. We've heard about excessive windage many times before with a few different manufacturers. It could be a couple things. Im unfamiliar with that specific DPMS, does this gun have fixed sights or BUIS's? |
Fixed sights. It's not the 3" at 50 yds. that bothers me so much, I'll work on that, just that the windage had to be adjusted so far to the left. Gunner |
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sent a bushmaster back to factory... same deal rear sight all way to right.... even though looked centered on rifle, when I got back from them, prob. solved. Explained to me that when indexing barrel, if off few thousandths, way off w/ irons nice when mechanical zero is also the actual zero |
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Two possibilities are, you have a barrel index problem, or the FSB is canted. Barrel indexing requires loosening of the barrel nut, which requires tooling. FSB canting can sometimes be corrected with a rubber mallet by tapping the FSB in the correct direction. The rubber mallet trick, while frowned upon by some, has helped quite a few folks in the same situation as your in. ETA: How were your groups after you obtained zero? Still 3" @ 50m? |
if it wobbles; fsb is canted, or barrel is not indexed properly. try the dead blow. |
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