New Development - Vertical Strings

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14 years 5 months ago #4771 by guido411
I have an AR-10T that was broken in properly and has been shown to print sub MOA groups only a few months ago (around 40 shots through gun) with factory ammo (Federal GMM 168 SMK BTHP). I am not a reloader so using factory ammo.

All of a sudden (100-150 shots through gun) my groups are stringing vertically where before they were cloverleafs or horizontal lines. Also, my cold bore shots are terribly high, sometimes +2"!! What gives?

Only things changed from then to now are:

-temperature +40
-went to PRI gas-buster charging handle

Background: This is my first AR and my first high-power.

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14 years 5 months ago #4772 by a Guest
Replied by a Guest on topic Re:New Development - Vertical Strings
Clean it with Montana Extreme copper cream and the BR 50. The bore is broke in in some areas and not the full length yet. Use Tubb final finish.MSH

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