.......... bad things seem to happen when i use those .177 benjamin discovery pellets (10.5 gr heavy w/ the little dimple they call a hollowpoint) , and the .177 pirahnas tumped even worse ( they were like $5 at walmart - so, yeah)...... believe it or not , the 9.7 grain winchester domes work well out of the .177 dianas i have had.... and the .177 premiers in the box , both 10.5 and 7.9 grains (or if you find a webley labeled can of these domed ones - they are consistent in size , or were).... most of my experience is with diana 48's and 52's in all 4 calibers... the sled guns were heavy (54)... in piston guns i have - when all else frustrates - h&n ftt and baracudas are usually a safe bet....especially in diana and hw's..... in diana magnums , i found jsb to be also accurate - but they lost power. i reckoned the skirts blew (soft lead). it's strange they really do best for me in pcp/co2 types.. - paul.