I have one of your .22LR M4 uppers, preban with A2 flashider (no bayo lug), purchased from CheaperThanDirt, with which I am VERY happy function and accuracy-wise. I have said so many nice things about it both here and at RimfireCentral.com that you ought to start paying me commissions! :)
I'd like to put one of those fake XM177 "slipover" flashiders on it to get a little more weight out front. Trouble is the flashider on it won't come off with a "normal" amount of torque on a proper wrench. Were these "permanently" attached in some way? I can find no evidence of pins. Is it silver-soldered or Loctited on? Any tips on how to get it off?