I think that's pretty good for a restored classic sporter with modest powered scope.
If its averaging outside 1 MOA for 5 shots then probably it could be improved with more work.
I would look at the rifle before trying more permutations of loading components.
Can anyone tell us how accurate BSA "mini action" rifles were in their heyday ?
Perhaps the action would benefit from some work: truing, lug balancing, trigger work or a new firing spring - accurise it better than original !
Also look at your testing gear. Groups can improve noticeably with a good adjustable front rest and sandbag plus a nice bunny ear rear bag, concrete bench, calm day, shooting alone ...
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