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Posted: 3/18/2011 6:56:10 AM EDT
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I stopped in to visit a friend of mine while on the road last week, and we were talking AR's and he has a Bushmaster, so I asked him how he liked it.
"I can't get it sighted in" After a little more talk I agreed to take it home with me and sight it in for him. It is an an xm15 A3 with detachable carry handle. Sporting only the iron sights. He sent it with some Rem and PMC 55gr FMJ ammo. I set a target up at 25 yards, and fired 3 shots. The 3 shot group was 6 inches high and 3 inches across. 
I thought this was pretty bad grouping so I looked things over and found the carry handle only finger tight. I used a quarter and tightened it as tight as I could get it to go. I looked to the rear sight and found it was bottomed out on adjustment so I adjusted the front sight extra to bring the rear sight back in place and shot 3 more. POI was about right but again the group was 2 1/2 inches across. I moved the target out to 50 yards. and shot 3 more. This time the POI was 8 inches high and the group was around 5 inches. I got to wondering about the ammo so I grabbed my Spikes LE 16 Middy that I had also brought out to sight in, and it was sporting a new Eotech XPS3. Using the same ammo it shot 2 one inch groups. Back to the bushmaster, I readjusted the front sight to bring POI down and shot 3 more shots. The first shot was right on, then shots 2 and 3 went back up 6 inches. 
At this point I filed stripped the upper and pulled the hand guards to see if i could tell if the BBl nut was loose. As near as I can tell it isn't. So I thought maybe it just really didn't like the ammo, so I pulled out a box of handloaded 55gr FMJ I had in my range bag, and shot a few more. POI wandered all over the target. So Now I'm scratching my head. Have I missed something obvious? Why is the accuracy so poor and the POI wandering so badly on a iron sight rifle???? I took it home and stripped it again. I looked at the BBl and bore with a flashlight, I checked the flash hider and anything else i could think of but cant find any problems. Anyone have any thoughts on what i can look for? I think I might pull the carry handle and put the eotech on it just to see if that helps. Any help would be appreciated this one has me stumped. |
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Ok first things, 3 shots is not a group.
You solved one issues with the carry handle being loose. You may have a perfectly good rifle that just does not like PMC ammo. Go shoot again; 10 rounds slow fire. Do not adjust sights or your point of aim. To be honest it does not mater were the shots are you just need to get a real shot group to determine how the rifle is shooting. Get a different brand of munitions, better quality. Do the same. Report back. If your groups are 2" at 50 with crap ammo, that's probably bought right. Adjust sights accordingly. If you are continuing to have issues swap out to another sight (sounds like you have multiple) again do not adjust for impact vs point of aim, just shoot 10 shots. See how the weapon is shooting. |
| Check to see if the front sight is canted. I had some issues zeroing 2 Bushmasters because of that. Had to send it back to factory and have them readjust it. They paid for the shipping too. If you can zero this gun then its time to call them and ask for a call tag. They will fix it. It is just annoying as hell. |
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Quoted:
Ok first things, 3 shots is not a group. You solved one issues with the carry handle being loose. You may have a perfectly good rifle that just does not like PMC ammo. Go shoot again; 10 rounds slow fire. Do not adjust sights or your point of aim. To be honest it does not mater were the shots are you just need to get a real shot group to determine how the rifle is shooting. Get a different brand of munitions, better quality. Do the same. Report back. If your groups are 2" at 50 with crap ammo, that's probably bought right. Adjust sights accordingly. If you are continuing to have issues swap out to another sight (sounds like you have multiple) again do not adjust for impact vs point of aim, just shoot 10 shots. See how the weapon is shooting. While I appreciate the input, a 3 shot group is plenty to know a rifle is shooting Poorly. 3 shots in a tight group may not mean much to show accuracy, but 2 shots at 25 yards without adjustment that are 3 inches apart are plenty to know sometrhing is not right. I'm looking for advice on what might possible be wrong. Wether or not it is shooting poorly has already been established. Thanks Ricky |
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sounds like the rear sight is screwed up to me. wouldn't be the first time. This sounds like the most likely problem. The aperture could be flopping around. Mount a rear buis or RDS from your rifle onto the bushie and see what happens. (I'm assuming the shrubbie has a fixed front sight). |
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Ok first things, 3 shots is not a group. You solved one issues with the carry handle being loose. You may have a perfectly good rifle that just does not like PMC ammo. Go shoot again; 10 rounds slow fire. Do not adjust sights or your point of aim. To be honest it does not mater were the shots are you just need to get a real shot group to determine how the rifle is shooting. Get a different brand of munitions, better quality. Do the same. Report back. If your groups are 2" at 50 with crap ammo, that's probably bought right. Adjust sights accordingly. If you are continuing to have issues swap out to another sight (sounds like you have multiple) again do not adjust for impact vs point of aim, just shoot 10 shots. See how the weapon is shooting. While I appreciate the input, a 3 shot group is plenty to know a rifle is shooting Poorly. 3 shots in a tight group may not mean much to show accuracy, but 2 shots at 25 yards without adjustment that are 3 inches apart are plenty to know sometrhing is not right. I'm looking for advice on what might possible be wrong. Wether or not it is shooting poorly has already been established. Thanks Ricky 3 shot "groups" aren't going to rule out operator error. Pick a point to aim at, fire ten rounds slowly, and come back to us with the POI group size. Posted Via AR15.Com Mobile |
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Follow your instinct. Once torqued a barrel nut to 35ft lbs. After 6 months or so, rifle grouped for shit. Felt solid, but spun right off with a wrench. Must have been 2 ft.lbs above finger tight. Retorqued to the next notch - problem cleared up. Great advice, when your done checking the barrel touque also check the crown on the barrel. People sometimes put strange hard steel things down the barrel from the muzzle end (  ) when they think they are going to clean the barrel. Just a little bump or ding on the crown can wreak havoc on accuracy, and especially on grouping....<><....:)
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I had a similar problem experienced when shooting Remington ammunition, I pulled the the bullets and found that the charges were of differing amounts, as were the bullet weights by slight differences. When you try the other items mentioned you might want to try changing ammunition to a better match grade ammunition and see if that solves your problem. I am not saying it is this way on all Rem ammunition but at least some gets out past QC. Could have been a partial box problem, but your handloads should have worked.
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I had a similar problem experienced when shooting Remington ammunition, I pulled the the bullets and found that the charges were of differing amounts, as were the bullet weights by slight differences. When you try the other items mentioned you might want to try changing ammunition to a better match grade ammunition and see if that solves your problem. I am not saying it is this way on all Rem ammunition but at least some gets out past QC. Could have been a partial box problem, but your handloads should have worked. Try 24.7 gr of RL 15 with a 69 SMK loaded to 2.25 COAL. That load shoots tiny groups in any 16" barrel I have tried. It's my go to 16" barrel load. |
| which sight aperture are you using? i had the same problem using the bigger hole rear sight aperture, flipped it to the smaller holed sight aperture and problem solved! your rear sight has two sight apertures one for close and one for normal flip to the normal sight. |
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Follow your instinct. Once torqued a barrel nut to 35ft lbs. After 6 months or so, rifle grouped for shit. Felt solid, but spun right off with a wrench. Must have been 2 ft.lbs above finger tight. Retorqued to the next notch - problem cleared up. Great advice, when your done checking the barrel touque also check the crown on the barrel. People sometimes put strange hard steel things down the barrel from the muzzle end ( ) when they think they are going to clean the barrel. Just a little bump or ding on the crown can wreak havoc on accuracy, and especially on grouping....<><....:)This would be my BET! I would check the Barrel torque first though! M4QUADRAIL 
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In for future reference.. Did you try shooting the upper on your lower to ruel out trigger pull? I know my standard bushy trigger was horrible and accuracy improved greatly with the RRA 2 stage trigger Brian Just the opposite for me, bush 2 stage in their DCM is perfect,my RRA 2 stage totally sucks.Went with the SAA-E |
| What twist is the barrel. Never really had an accuracy issue with Bushmaster stuff myself. XM A-3 is a 20 in flat top correct? Mine's a tack driver but it's homebrewed with all Bushy parts 1-7 twist govt profile except Colt BCG, trigger springs and furniture. Don't personally like bottomed out carry handle sights myself and I'd change that (allen wrench) just because it would bug me and I'd probably use a screwdriver to tighten handle also. Wouldn't really think that would have much effect at 25-50 yds but can see how a 25 yd zero might be a little high at 50. Check the barrel torque as stated above for peace of mind but even with canted FSB you should be able to sight it in. I've also never had any real consistent success with PMC ammo but others here have. Think I'd run a patch or two through it also (could be fouled). Could be the shooter. Swap a few parts around and check. Like put the carry handle on your carbine and see how it sights. Except for screwed up barrel crown it should be an easy fix. Let us know. |
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I have a Bushy ORC carbine. At 50 yards, it shoots 2 inch groups and at 100 yards, about 3 1/2 inch groups with the usual cheap ammo. Maybe I'll check the barrel nut as someone else suggested.  same here A1 Bushy 14.7 hbar best I could do is to keep all my shots into a 2 inch square useing Q3131 I slap a 3.5-10x bushnel on my Bushy 20hbar. useing 69gr federal gold I could shoot clover groups at 100Y prone |
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