Largest caliber in Springer?

if you want a big pellet in a Springer Go with the hatsan 125 .25 it's got near pcp fps but no air pump or scuba tank needed i have it in .25 .22 and .177 all in TH spring i love then all, although I have to use heavy pellets in the .177 or they become super sonic and since I shot in my backyard i try to keep the noise tolerable for the neighbors i agree that the 135 .30 is probably not worth it just on the price and availability of the pellets. H&N has a great variety of.25 pellets at reasonable prices i recommend any of their copper coated ones they group very well hit super hard and have never disappointed me