Dave is absolutely correct.
My Four M1s all like the very cheap Remington 1 oz 2 3/4 VERY well. One of them shoots that round the very best. One shoots Breneke 7/8 oz the best and the one I let one son have liked the expensive copper solids the best. One likes the very cheap PMC 3/4 oz 2 3/4 the best -- but I don't know if PMC still makes that little slug any more. PMC has gone through a LOT of changes...
BUT, all of them were capable of 6" or better at 100 yards which, because it was me shooting them, means they are probably capable of 2" or less. But, strong note here, all of them had a few brands that they wouldn't shoot well at all. I remember one of them that would NOT keep the Federal 1.5 oz within 2 feet at less than 100 yards...