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Posted: 9/21/2011 4:22:35 PM EDT
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i recently inherited a colt 9mm ar15 that i believe was manufactured in the 80's. it has an a1 upper receiver and a 2 position stock. the rifle belonged to my grandfather and lived most of its life in full auto (legal auto sear). of course, i was glad to receive the gun. i thought it would be great for my grandfathers gun to live on and serve as a nice plinker/ trainer. the problem is, it may as well be a shotgun.
as soon as i got it i took it and my 5.56 ar15 to the range and started shooting. i got the usual <2" groups at 50 yards prone with my 5.56 and an astounding 18" at 50 yards with the 9mm using reloads. the reloads make 4 inch groups at 25 yards when i launch them from a Beretta92. after a cease fire i pick up the gun to shoot and the hand guard just rotates. OK, that's not even safe. so i go home, disassemble the whole thing, order a new 6 position tube and moe furniture just to modernize it a little. when the parts arrive i reassemble with the new parts, and torque the barrel to German specs. next range trip i take the gun and federal american eagle ammo thinking i had solved the problem and i get 16" groups. not very usable. what could be the problem? as i said before the gun did live most of its life in full auto. i saw this gun go through a few back to back 30 rounders when it still had the auto sear. could the barrel have overheated at one point? its pretty thin. thoughts? |
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What do you mean "torque the barrel to German specs"?
How does the barrel look after you've cleaned it? Any obvious flaws? Rings? Damage to the crown? Is the flash hider on tightly? Have you had someone else try to shoot it with the same results? A few back to back mag dumps shouldn't hurt the barrel and I doubt the barrel is worn out in a 9mm but anything is possible. |
german specs are guten tight . i don't have a torque wrench. my dad did also shoot it and got the same results. i know the accuracy isn't because of me. i regularly get much better accuracy from my 5.56 carbine. the barrel and crown are fine. the flash hider was tight as well. any other ideas as to why i'm getting 32moa accuracy? i was hoping for better accuracy than what you can with a .22 conversion kit.
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I bought a used 9mm upper that had been on a host lower. The rifling looked pretty worn out when I rec'd it, but after cleaning the bore a few times with a lead out patch, the rifling looked great. Apprarently the previous owner had shot a lot of lead reloads, I suppose for the affordability, and had leaded it up pretty good. You might check that. Good luck. John |
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+1
Due to the age and caliber, I'm going to guess it has seen a fair amount of soft lead reloads that have left a whole lot of build up in your rifling. Teflon-coated lead projectiles can also make for a horrible amount of clean-up to be done. I bet a good cleaning (which will take quite a while if it's that bad) will bring things back in order. Don't use stainless steel brushes, but lead-removing solvents are fine (watch out for amonia-based products that can't be left in the bore for very long). Brownell's also sells a nifty lead-removing gizmo that works mechanically on heavy leading. It's basically a brass mesh or screen material that is pushed through the bore on a rubber-tipped mandrel (on the end of your own cleaning rod). Buy the one for a .38 Special as it will work in your 9mm. It's pretty cheap and it will more than pay for itself in saved labor on your first cleaning job of this magnitude! Quoted:
I bought a used 9mm upper that had been on a host lower. The rifling looked pretty worn out when I rec'd it, but after cleaning the bore a few times with a lead out patch, the rifling looked great. Apprarently the previous owner had shot a lot of lead reloads, I suppose for the affordability, and had leaded it up pretty good. You might check that. Good luck. John |
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