Posted: 9/19/2006 8:08:31 PM EDT
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Guys, I have a somewhat puzzling accuracy issue with my AR - I can't get the rifle to shoot consistently below 1". Specs on the rifle: Mega upper and lower, Wilson chrome-lined M4 carbine 16", DPMS stock LPK and trigger, YHM free-float fore-end, Bushy Mini-Y Comp. Glass is Burris Full-Field II set at 9x, and yes, all screws are tight. I am hand loading, and the best I have done is with 55-grain Hornady V-Max Moly bullets over 22.4 grains of Hogdon H-335 OAL 2.250", a CCI#41 primer, a LIGHT roll-crimp (Lee die) on LC brass. All reloading is done with a Rock Chucker, and I have the RCBS Chargemaster 1500 powder dispenser with electric scale. Every round is weighed individually. My gut tells me that I can be getting 3/4" with this setup - but the best I have gotten is 1.25." What am I doing wrong here? |
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It could be you...are you shooting from a good, solid rest? How is the trigger...are you jerking the gun a bit when you pull the trigger? Try not crimping... (thier is much debate about this...see what works for you) Try shorter bullet seating depths if you can. Try a few different bullet designs...sometimes cheap, flat base bullets work surpriingly well. I use a 68 Hornady in my Armalite NM. Try stick powder instead of ball...Varget, Benchmark, or even IMR4895 works well..although I have had good results with WC844 (H335 equivelent). Try different powder charges...load 5 rounds in .5 grain increments up to max load to see what works the best... often the best groups are somewhere in the middle between starting and max load. |
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Let someone else shoot the rifle and see if the results change. Get some good factory ammo and see if results change. Change weight of bullt see if that helps. What twist rate is the barrel? Check muzzle crown. Really clean the barrel and start over. Change scopes and see if that may be a problem. |
Thanks, and no - I haven't yet bought "item number 721" for the field kit. Sometimes shooting sucks. I am getting a little tired of doing the "gear-queer" thing in pursuit of the magical 1 MOA.  Yeah, I know I need the chrono to get the lowdown on how consistent my loads are. It's another $100, and I don't have room in the No-Car Garage in my tiny condo to put even a new cufflink into. I gotta move. I need a basement! 
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Thanks for your help! 
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Not good! Fortunately, it happened while it was in my cartridge box, not in the chamber. I don't think that I am crimping too much, but you never know. They say that new reloaders never gauge this correctly. Perhaps I am over-crimping?
That may be an issue. If I find out it was the scope, our friends in Greeley, CO (right up the hwy) will be getting a warranty visit from me. |
I NEVER crimp for .223 or any bottle neck rifle cartridge...just seat the bullet...I have loaded thousands of rounds for HP matches and have never needed to do this to avoid bullet set back. I load my rounds out ot mag length...especially with light bullets..they are usually not long enough to engage the rifling if loaded out to mag length.. By shorter seating depths..I mean bullets out longer. If you already at mag langth thier is not much you can do in this regard. For heavy bullets like a 79 grain AMAX...I load past mag length...to get the seating depth, I just put a bullet in a sized case, and chamber it in the rifle... set the seating die and back off a hair... I have even loaded them to the point where they engage the rifling on chambering...I have never seen presure signs (I don't think you could get enough stick powder in the case anyways). I shoot the heavy bullets single load in the 600 yard slow fire stage of a match. Sounds like you may not have enough neck tension..try lubing inside the case necks... I have heard of guys chucking their expander ball in a drill press and taking a bit of metal off with some emery paper... Alternatively it could be your sizing die is out of spec? Borrow a buddies sizing die if you can. |
A lot of good, solid advice here. Thanks pv74. I'm not sure I could have gotten better advice from the reloading section! I will look at the crown tomorrow night and see what I need to get to remove what I suspect is baked on carbon. I am thinking that I may just take the rifle to a smith if I can't get better accuracy with factory loads. |
Might have a LOT to do with this. It's almost impossible to get chrome to evenly line a barrel perfectly. You almost never see a chrome lined barrel on a firing line at a serious match because of that. OTOH, if you are lucky enough to get a chrome lined barrel that really shoots, it will last a LONG time. Remember, the big boys that shoot serious competition seriously often rebarrel after 3500 rounds, and sometimes less. They'd use chrome lined barrels if they could CONSISTANTLY get first rate accruacy out of them. |
Thanks You will also notice your groups tend to change a bit just after cleaning...then tend to settle in after a few shots. Before a match, I practice..then leave the rifle dirty for the actual match...it won't do anything to the gun in that small timeframe. Also, a warm barrel will have an effect on acuracy...let the barrel cool a bit between groups... it may help. Use a GOOD copper solvent for cleaning...Butches bore shine, Montanna Extreme or Sweets 7.62 are good ones. Hoppes just does not work IMHO. Soak the crown of your bbl in a good solvent to remove the carbon...do not try to remove it with a tool of some sort...just a cloth and solvent. Also...a compensator can have an effect on accuracy from what I have heard...I prefer a plain jain bbl with no comp or flash supressor for a match rifle. .223 does not have much kick. |
Spot on... Didn't notice the chrome lined BBL... and YES they do rebarel more often then we do (most regular shooters never do) Didn't mention the distance you are shooting at... If it is 100 yards (going to assume this)... For an M4, 16" chrome lined bbl with a comp... 1 1/4 MOA is pretty darned good  You may have nothing to complain about (altough I thnk you should look into that neck tension issue I posted about earlier). An M4 carbine..even if free floated is no match or varmint rifle...The rifle seems to be doing its job admirably if my assumptions regarding distance are correct. |
Sitting back, reading, and recalling the particulars about this sittuation makes me think that 1.25" is probably the maximum practical accuracy I can expect to get out of this chrome-lined, comped, 16" carbine. Oh, yes I am shooting at 100 yards, so I guess that I should not complain about a 1.25 MOA rifle that's good to go with probably 1000 rounds out of the barrel. |
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Try 52 gr Sierra MatchKings over 27.0 to 27.4 grains of RE-15 in a Winchester or LC case primed with a Federal primer. If your gun won't shoot this bullet, it probably won't shoot anything well, IMHO. Shitcan the crimp. I doubt the uber tough CCI #41 primer is helping things much. |