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Gemtech did mine. Very nice work on the barrel nut. I have no idea how they match it up so nicely.
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The way I match them up so nicely is to make a pre-threaded oversize protector before threading the barrel (essentially a thread-protector blank). Then dial the barrel in to less than .0001" runout (very tough to do). Thread the barrel, recheck runout, thread on the thread-protector blank, and then finish machine it down to .0001-.0003" over the barrel OD. Face front of protector off to however you want it, then remove the protector (might be very tight from machining process but I've never had one require anything more than rubber jaw pliers). There with be a very fine edge on the back of the protector. Lightly knock this off with a file and you will now have a thread protector that match the gun. Very, very close inspection may show a slight mis-match or OD variation but it's on the order of 1/10,000th of an inch and is very tough to see.
The faster "dirty" way is to do as above with the knurled thread-protector. Knurling back to the edge hides the mis-match.
Another way to do the matched, smooth protector start similar to what I do with a blank except instead of dialing in the barrel so close you can turn down the entire barrel OD a few thousandths... Typically the problem with this is that now the engraving/roll-marks on the barrel look funky. So to get rid of those you have to turn quite a bit off the barrel OD until the roll-marks are gone entirely. Now your front site will start to fit differentely (changing POI and how the contoured site fits the contour of the barrel). OTOH, if your barrel doesn't have roll-marks, dial the barrel to within .001" and just turn .002" or so off to get a consitent cut all the way back...
There is no perfect way to do it, all of them have their draw-backs. I prefer to take the extra time to do a perfect setup (sometimes I can spend as much as 45 minutes dialing in and checking/re-checking runout) vice turning extra material off the barrel.