Shot group goes to shit after about 10 rounds

[isItFallYet]

I had a similar issue with a Browning BAR. 1st couple of shots were very accurate. After a few they’d start wandering. Even with a lead sled. The issue was the stock would heat up and causing the barrel to land in different locations (not float). Took the stock off and sanded about an 1/8” off the inside and that fixed it.

 

[davsco]

as above, hot barrel, shooter fatigue, prob has nothing to do with cleaning or lack thereof.

fyi, make sure you're zeroed for your cold bore shot with the ammo you will actually use hunting, or at least know where you will have to hold for that first shot. some rifles it doesn't matter, some it does.