Saw a recent thread asking about a load for a 200gr LSWC. Couldn't help there but figured I'd share one I have for the Lee 252 LSWC (260gr as cast from my mould in ACWW).
I'm using Win and RP Brass, Federal or CCI Large Pistol primers (doesn't seem to matter which), 5.0 gr of Unique and Speed Green. Loading as cast til the case just covers the crimp groove and just enough crimp to take the flare out of the case mouth.
Perfect reliability with well over 1000 down range. VERY minor leading (maybe because my pistol has polygonal rifling). 5 or 6 strokes of a bore brush with chore boy every 50-75 shots and the bore looks like brand new.
I'm getting 815fps out of an HK USP45. Not blistering speed but its quite a thumper with a 260 grain boolit and the most accurate load I've found for the pistol. Far better than I can get with the 200gr. LRFN. I'm not a good pistol shot but this load is consistently shooting in the very high 90's at 25 yards. (I usually end up with a couple just outside the 10 ring per mag of 10 rounds....😑 Almost certainly an operator issue.) At SD distance (the proverbial 21ft.) its boringly accurate. The only question is how many won't be X's and every one is because of a defect in the nut behind the trigger.
Work up in your pistol. YMMV. Use at your own risk.
Hope someone finds this useful. Be safe!
BH2