Trouble with remington 222 :(

[bobcat trapper]

I am "kind of" having trouble with a Remington 799 in 222 Remington. It shoots one hole groups but if i clean the barrel it shoots like 5in 3 shot groups for the first probably 40 rounds before it settles in. Any idea why and how to cure this? I was thinking about trying some moly bullets to see if that would help settle it in faster. The load is 21.5 grains of h-322 with a 50 grain sierra blitz king or v-max.