I received and fitted my new sideshot magazine the other day , and today while going through it and figuring it out I thought I’d try to see what the longest pellet would fit . To my surprise , even the 225-39FN bullets fit with just a slight bit of room to spare . They measure at.410 “and everything cycles just fine . This is quite a bit deeper than the factory mags pre MKII . Good news for the slug shooters . Now to size these down to see if they work in the barrel. If anyone was holding off due to the short depth of the mags the MKII will take up to 40 gn . Now to get the power up to launch these to 900+ FPS.