I've shot KD AQT's a couple times with my AR (24" 1 in 9" twist) and found out something interesting this weekend at 600 yards. From 100 to 400, PMC Bronze .223 drops ~2MOA per 100 yards and is quite accurate (it helped me get a 220 KD this weekend), but after 400 yards, it is all over the place. From 400 to 500 yards, it is at least a 4 MOA drop and at 600 it was actually keyholing. Out of 20 rounds at 600 yards (albeit very rapid fire), I only got three hits and they were all sideways.
Overall, I am very happy with the ammo (especially its cost at <$6/20 rounds), but at least in my rifle, it is only useful out to 400 yards.
We emphasize the you need to learn your rifle, but make sure you learn your ammo as well. Come ups are always critical, but knowing the limitations can come in handy.
Mike the bronze has a few things about it that make it not quite capable. one it's a .223 VS. a 5.56 load. IE not full power, two is a 55gr FMJ which is not quite compatable with your 9 twist barrel which is more of a 62-69 gr bullet twist.
55's work fine in 1-9 twist although the original M-16 used a 1-12 twist. The 1-7 or 1-8 is for the longer/heavier bullets which are a better choice at that range.
Bullet shape will play a role also. Have you tried any other 55 FMJ ammo?
Check this link out: http://books.google.com/books?id=6Ocu_C6xMdwC&pg=PA28&lpg=PA28&dq=.223+55+fmj+600+yard+performance&source=bl&ots=g3H1MjFYrI&sig=uFSe69xrRJILw1E2bwn36tUUMzk&hl=en&ei=5Z-xTambMMyCtgfIt4ngCw&sa=X&oi=book_result&ct=result&resnum=2&ved=0CB0Q6AEwAQ#v=onepage&q&f=false (http://books.google.com/books?id=6Ocu_C6xMdwC&pg=PA28&lpg=PA28&dq=.223+55+fmj+600+yard+performance&source=bl&ots=g3H1MjFYrI&sig=uFSe69xrRJILw1E2bwn36tUUMzk&hl=en&ei=5Z-xTambMMyCtgfIt4ngCw&sa=X&oi=book_result&ct=result&resnum=2&ved=0CB0Q6AEwAQ#v=onepage&q&f=false)
It might be that your bullets are going transonic/subsonic which will cause the keyholing too.
RR
PMC makes up a solid 95% of what has been used in this rifle and I am definitely comfortable with its limitations. I wasn't going into this expecting anything great out of it at 600 but was surprised with its complete lack of performance. I'd like to try some M855/SS109 at 600, but for anything serious, it'll be 69 or 77 grain SMK. That however, is beyond the scope of our focus at Appleseed.
My main intention here was to encourage people to learn their ammo as well as their rifle. I know for sure that my rifle is more than capable of a very high level of accuracy, but in this case, my ammo was not and it was great to find that out.
RR, thanks for the link. I've definitely going to read that completely when I have some time this weekend. In a quick scan of that article, I just realized that my come up may have been lacking as well and it is possible that I was skipping rounds off the berm into the target (the target were elevated above pits). We jumped from 400 to 600 and I made my best guess, but I expect that I under estimated by about 3 MOA. Combined with the 20mph half value wind, I was at a disadvantage for sure.
I'll be back at this range again at least twice this year, and I'll give it another go to confirm that either the ammo is lacking or that I didn't really know my rifle as well as I thought ++)
Absolutely, knowing your rifle and how it acts at different ranges is crucial.
I had shot my AR at 100 and 300 yards with the same PMC 55 gr. ammo, which gave me good groups. Recently, I shot it out at 500 yards out of a 16" 1/7 twist AR and got hits on a 20" steel plate; there was a steady 10 mph cross-wind, but the effects were almost negligible. A slight (2 to 2.5 MOA) hold negated the wind and allowed me to shoot 4MOA groups. If I missed at all, it was me, not the rifle or ammo.
At that distance, 600 yards, if you were off even a little bit with your come-ups, your shot would be way off...elevation-wise, not windage wise. Unless those 3 hits were just lucky, I would say that the come-ups weren't the issue. The wind could have played a HUGE part in the inaccuracy if it wasn't a fairly constant wind. Was it a constant 20mph half-value wind, or was it a varying wind?
Keyholing could only be caused by lack of concentricity of the bullets, or axial precession caused by canting. That can be caused by manufacturer's defects (bullet defect, or improperly seated bullets, i.e., canted in the case). The 1 in 9" twist should stabilize those bullets just fine. I'd suspect the twist if you were using 80 grain match bullets, not 55's.
Quote from: mike93lx on April 19, 2011, 12:12:47 AMOverall, I am very happy with the ammo (especially its cost at <$6/20 rounds), but at least in my rifle, it is only useful out to 400 yards.
If you like the cost of that stuff, try some Wolf or Bear. It'll give you better performance at about 2/3 the cost.