Not tried the SMK 26, but have got the SMK 25 (in .177) bit of a 'beast', but accurate enough and it'll match most of the pistols at the club in the pistol 'corner'. I found that it was pellet fussy, in that some pellets were grouping(?) all over the target, and only two types actually would group - strangely enough, Spitfires & Daystate Li (it gets fed a diet of Spitfires!)
Hope you've stuck with it, I'd not swap any of my pistols, as they're good fun (got C02, BB, SSP, and springers)