They can be a little hard to find good loads for.
Cousin has one just like it that is a little spotty on accuracy. Of course his idea of ammo is whatever he can find the cheapest, usually with brand names he can't pronounce.
Mine is a .250-3000, shoots 3/4" groups with 75 gr. Sierra hps and Varget. Nothing else I've tried comes close, different 75 gr. bullets, different powders, just that Sierra hp and Varget. 100 gr. bullets will do 1 1/4" but usually have 2 close and the 3rd out a bit. I've threatened many a time to put a better barrel on it, but keep it sighted for the Sierra instead.