Sometimes I've been fooled by the crummy paper they use in targets, but you had clean drilling at 5 yard, so I wouldn't think the paper is at fault. It looks like you've got bona fide keyholing there.

To me they should drill as clean at 10 yards as five, but it's probably not the ammo because you shot clean holes the first time again. i do suspect a fouled barrel and maybe try another ammo.

If you barrel is a loose fit on the ..22 bullet it may not be spinning correctly and starts to tumble after the first few yards. Or fouling could keep the bullets from catching in the grooves of the rifling and not imparting enough spin.

Definitely clean the thing. That is the cheapest route.

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