it shouldnt hurt...they are saying it should pattern best with #5...i am a fan of #4 and i work to find a #4 that will patter nice in my guns...its all about the constriction .668...i heard tonite watching outdoor life that .665s are usually better with 4 and 5 and .655 i (think..i know it was tighter) is usually better with a smaller shot..when all the big shot goes through a tight hole it spreads wildly in most cases..im not sure why i think it kinda ricochetes off the sides when it gets constricted and just flings out wildly but thats juts my guess and i thought about that for a while......id shot the 4s and if they dont patter good get a box of 5s and maybe a diffrent box of 4s and see...the first box i tried in my remington patterned so great i didnt try anything else..i doubt it can get much better..if it can id have to scope it and shoot it like a rifle because it would be that tight out to 20yds...i dont ever use "turkey loads"..my dad bought a box of 25 remington nitro mags with 1 5/8 ox of buffered #4 mags...works fine in the 4 or 5 guns we shot them in...i did shoot 6s out of my mossberg before and it patterned worse so i stayed with 4s but i got a remington and it loves the nitros in 4...my dad rolled a few bosstoms with them loads..