Yup, I got the same result -- inconsistent accuracy with the 180 grain XTP and Lil Gun, and a huge improvement when I switched to the Hornady 200 grain jacketed round nose. Haven't used Lil Gun much with the 200, but had good results with a case full of Reloder 7. Can't find IMR 4227 around here at all, but I suspect that it's about optimum with a 200 grain jacketed bullet. Have also had very good results with the 215 grain Lyman 358627, made with #2 alloy, gas checked and lubed with plain old Lyman Alox. My bore slugs .357", but have had best luck sizing the big SWCs to .359". I bet 4227 would do well with this bullet, too, if I could just find some.
My .357 barrel has a typical very long throat, long even after being reamed to Max. Instead of agonizing over trying to seat the bullet close to the leade, I just seat the jacketed 200 to the cannelure and crimp, and the Lyman to the rear crimp groove, lubing only the big lube groove and the little gap between the rear driving band and the gas check. That yields a pocketable cartridge with no exposed lube, and still doesn't seem to lead the bore to any great extent.
I had a Williams aperture sight on the .357 barrel for a long time, but have finally given up and gone to a 2.5X scope, my eyesight having gotten weaker lately. With a wood MC stock on the frame, there's no recoil to speak of, at all. You know you've touched off something bigger than a .22, but the little shove that even a full-throttle load gives is not enough to make me flinch. The .357 Max is just about a perfect "old man's deer rifle".