Decided to cave into this Hope brake love-in theme.
Tuesday night pulled off the XTRs and mounted up the Hope X2 race brakes. Took the pads out ready for bleeding the next night. Haven't used DOT fluid brakes in a while so, being super cautious, wrapped the calipers and levers in rags in case of spillage.
Wednesday night, fight kids into bed and head out to the shed. Shorten the brake lines, start bleeding the front brake. Fluid coming through the hose, few pump/release cycles later no fluid through the hose. Get down to inspect, hmm, fluid pouring on to the floor. Maybe hose has come off, no. Remove rag from caliper. Fuck, with the caliper all wrapped up I forgot to put a bleeding block (or something) between the pistons. One piston completely popped out. Dick head.
Anyway, carefully lined up the piston and it pushed back in easily. Seems to have bled fine after that and no obvious leakage from the piston. Yet to ride them. Hopefully haven't damaged a seal.