GT Specialties barrel changing ....

[G.T.]

Hi Charlie, well, equipment wise, it's kind of an on-going design on the fly type of quest?? First, I had to have a receiver fixture made that supports the complete receiver, after that was satisfactory, I had an inside fixture made to support and also use the interior surfaces to help turn the receiver... Then windows had to be cut to see what was occurring, and finally, a wrench designed to give max support and leverage to the whole shebang... Anyway, that was just part on the issue, holding the barrel was just as problematic... I had experimented with several setups, and finally it came down to a set of two X two overall, alum. block with the correct taper machined into the center.. I then in turn, clamp the fixture barrel to my work bench with an impact wrench and start assembling the parts... The three I have done so far, have turned in about half way, with some effort needed to finish and get close to the marks...Then it's a matter of compromise between, three factors.. the front sight base, the extractor relief, and the timing marks... I try to get the front sight base perpendicular to the toggle knobs, and the top level with the rear sight... I'm confident this is within 1/2 degree when finished.. and if the extractor relief is aligned to accept my byf test toggle ass'y, then we're good to go... least important is the receiver /barrel alignment marks, they are used primarily as a relative guide, and although close, probably will not index with complete accuracy, they do give you some reference as to how much further you need to go, or ... how much too far you've already gone!!?? ... Needless to say, the barrels seem plenty tight long before the marks are reached.. While doing this type of operation, I've come to believe that the receiver witness marks were made when the receiver was made, and the barrel, pre marked or not, was indexed to it later, or after final assembly... I'll learn more as we go.. just wanted to let the guys know we're up and running.. I have more mods on the blocks for the future, just for accuracy and correct comparative torque values... It's pretty neat and fun when you have the right stuff! best to all, til...lat'r...GT