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Posted: 4/1/2017 10:17:42 PM EDT
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How much accuracy can I expect from a new (300 rounds) Bushmaster carbine? I'm not a bad shot with my bolt action rifles. Not so with the AR. I have a 4 - 16x Nikon scope on it and the best I can do at a hundred yards is a scatter of about 6" diameter with 5 shots. If I bring it back to 50 yards, I get them all in the black but not in anything approaching a "tight group" I get with the bolt guns at 100 yards.
Is it my shooting or is 100 yards beyond what I can expect from a factory barrel on a new rifle? Will it get any better over time. Thanks for your help. Mike |
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For starters you need to give it a thorough cleaning, both the chamber and bore. Then you'll need to use quality ammunition if you actually want to discover the rifle's potential.
For 100 yard groups 52/53 grain match ammo or handloads using Sierra, Nosler or Hornady match bullets in those weights will stack up nicely on target from 90% of all rack grade firearms. Check out Black Hills Ammunition if you can't afford Federal Gold Medal Match. Australian Outback is another option. Try heavier bullets if you're going to shoot longer distances. |
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Excellent advice above.
OP: What ammo were you shooting? A lot of bulk or budget priced stuff is about 2-1/2 to 3 MOA at best. Many chrome lined 1:7 5.56 barrels don't do much better. Check your scope mount and make sure it is solid. Mil spec 8 lb trigger does not help, either. Thoroughly clean the chamber and bore, get some good ammo, take a fouling shot or two, then shoot for groups. |
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I'd like to know what ammo and what barrel twist? What's mil spec for accuracy? 6"? You need to test it from a good rest with several brands and several weights of bullets before deciding it's not accurate. Try good ammo, not steel cased or fmj. Even so though, I've shot a group I could cover with a quarter from fifty yards with a ptac parkerised barrel and iron sights using m193.
There are a lot of things it could be. Loose barrel, bad scope, etc. Is it a cheap Chinese scope? |
| Bushmasters are generally accurate rifles. I am going to guess you have an issue with ammo, scope or scope mount. If you have a set of iron sights please test the rifle with them. If it shots good then you know it is not the ammo or the gun but the scope or scope mount. |
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Everyone pretty much already cover all the bases: Good ammo, precision trigger, loctite all moving parts.
6" at 100 yard is abysmal. My piece of shit 20" .223 Wylde barrel is getting 1.5" with Fiocchi V-Max 50 grains all day. Generally, with the quality of barrel today, the norm is about 2"-3" at 100 yard. |
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You should expect much better accuracy from your set up unless there is something wrong with it. I suggest a good cleaning with attention to barrel fouling. Clean it until patches come out white which might take some times if it's not been done for awhile. Inspect the barrel crown. If it's nicked up, that will affect accuracy.
Then as already suggested, check your scope mount to make sure it's not loose. It might even be a good idea to remount it paying particular attention to torquing the screws to the recommended amount and making sure the reticle is level. You didn't mention what FCG you have, but a good clean breaking trigger goes a long way towards accuracy. Some inexpensive options for FCG are LaRue MBT, Velocity drop in or ALG ACT. I really like the LaRue. Then some reasonable ammo. Federal Fusion is pretty good but pricey. I recently shot some sub MOA groups with Speer Gold Dot 55 gr, although I did have some short stroke issues with that ammo because it is fairly low velocity. The Gold Dots can be had for about $12 for 20 box. |
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First of all, thanks to all for your responses. They've been extremely helpful. I'll start by trying to answer your questions. The barrel twist rate is 1:7. The ammo I've been using is Federal American Eagle 55 gr FMJ. Not the best nor the worst, but affordable. My scope is a Nikon 4-16x. I checked the tightness of the base and rings and found that the rizers were somewhat lose. They're tight now. The reticle is level. I recently installed a CMC 3.5 lb. trigger that I really like. It compares well to the more expensive after-market triggers I have on my bolt guns.
My scope is a Nikon 4-I6x, The reticle is level. I checked the tightness of the rings and mounts and found that the rizers were loose. They're tight now. I cleaned the bore and chamber today and was surprised to see the amount of copper fouling there was after just 300 rounds. I haven't thought about until now, but I haven't found a stable bench rest or shooting position for me. I haven't been using a rabbit-ear bag under the butt. I'll work on that this weekend. I bought a box of Sig Sauer 69 gr. match ammo. It comes highly recommended. If it shoots well and I know the problem isn't the rifle or scope, I'll start working on accurate hand loads. I was surprised to see that there are very few match bullets in 55 gr. or less. They were mostly in the 65 to 79 range. I'm going to the range within the next couple of days and I'll let you know the results. I'm expecting better than before. Thanks again, Mike |
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Federal XM193 seems to group pretty decent in my guns.
American Eagle .308 has grouped very well in my M1A American Eagle in .223 for some reason sucks rocks in my guns.. It could be a big part of your problem. And then getting a good rest when testing. You might be having to learn how to shoot an AR a bit too. The basics are the same but a gas gun isn't as easy to shoot as a bolt gun, IMHO. Last time I did a little bit of shooting at 100 with a scope (2x7). I tested a few loads and was getting 1.5-2 moa approx and then that lower left group with American Eagle was 5-1/4". 
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