It is certainly worth checking that and, if you have the means, to reduce the depth of the flange a little. Also, if you were to strip the gun to the point of piston removal again, to insert the top hat and guide into the piston and make sure that the ends of each are not touching one another. If you needed to replace the guide, the standard, later, two-piece synthetic and steel HW guides are actually pretty good. As long as guide to spring fit is good, this could well be an option. You'd need to measure the spring ID and for someone to shout up with the OD for the HW guide. If that's not going to work, pretty sure Monsieur Tinbum could sort a bespoke guide for you if you provided measurements.