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Posted: 7/26/2010 10:38:08 AM EDT
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Here's my setup I've been running for 3-gun for a year. It has been accurate and 100% reliable for about 10K rounds and then nose dived dramatically this weekend during a training class.
Colt upper Noveske 18" spr Surefire comp PRI CF handguard JP tactical bolt carrier JP bolt Swarovski Z6i scope Larue SPR E mount 69 gr SMK handloads and 55 gr FMJ handloads Problem: Gun groups fine when cold. After 8-15 consective rounds, group opens up to about 7" at 100 yards, then I get random fliers that are FEET off the target. I removed the compensator (which showed bullet strikes that never were there before this problem arose) and started with the gun cold. Same problem as above. I left the comp off and popped on a Leupold 14x scope on a new larue mount to rule out the swarovski. Same problem as above. The barrel nut is tight. The crown on the barrel looks fine. The larue mount screws are tight. I'm building a new upper as I'm under the gun for an upcoming competition but I am curious about this problem. I'm thinking there is a fracture in the barrel or something along those lines. Any ideas what the hell could be happening? |
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Quoted:
I could be wrong, but it sounds like you're barrel is shot out. After 10k it might be time for a new one. It's a Noveske ... so it's SS and shouldn't be shot out at 10k rounds. IMHO Could be some build up fouling the bore ... get some good solvent (I use Shooters Choice) and clean the shit out of it. |
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The only barrel that it still going to be fresh after 10K of rounds is a chrome lined one.
In a Broach cut barrel, plan on getting 4K before it starts spraying, and either a SS or standard steel button cut barrel, about 9k before it starts spraying as well. Now having said the above, is you are still printing until the barrel heats up, then either increased barrel whip or forearm pressures are the casing the spraying. |
| My admittedly limited understanding is that stainless barrels will go out more suddenly than chrome-lined. They are good to go until one day they just up and die. 10K rounds is a bunch, especially if you are doing mag-dump drills in training classes or fast strings in competition. |
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Quoted:
My admittedly limited understanding is that stainless barrels will go out more suddenly than chrome-lined. They are good to go until one day they just up and die. 10K rounds is a bunch, especially if you are doing mag-dump drills in training classes or fast strings in competition. Barring how the rifling was produced, and if the bore is chrome lined or not, it's the other way around with SS bores being a tad more resilent on the rifling that chromemoly barrels. But in the case of SS barrels, over heat them and they will pretzel on you quickly (reason why you do not run SS barrels in a full auto rig, nor just go blasting to see how hot you can get the barrel). As stated for rifling, about the 4K mark a Broach cut barrel is going to give up the ghost (will just pick a round count that it will no longer group tight), while button rifled barrel do start to loose the mark around the same time.count, but the groups start to open up slowly from that point, and around the 10K mark, be at the point of just calling the barrel a spray master. |
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Quoted:
I thought the polygonal rifling of the Noveske's SS barrels made them last longer? http://en.wikipedia.org/wiki/Polygonal_rifling |
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Guns will go bang as long as cartridges feed into the chamber.
No matter what steel the barrel is made of, accuracy past 25 Meters will SUCK long before the 10,000 round mark –– IPSC performance included (an A zone is pretty big). Chrome lined and cold hammer forged will die like any other (chrome will peel at the throat and the high spots of the lands). WWII German industry used hammer forging to make LOTs of MG42 barrels quickly and cheaply. |
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I'd go with another Noveske, but get their chrome-lined bore. It's plated to the same thickness as the M249 (roughly twice the thickness of an M4), so it should last longer than pretty much any other AR barrel and provide plenty of accuracy for 3 Gun competition.
This interview provides some good insight - http://www.defensereview.com/noveske-rifleworks-n4-light-recce-carbine-john-noveske-interview-part-one/ |
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