Brownells Gunsmith Tech Corner - June 2008

Question: I like the finishes resulting from your Gun Kote and Teflon/Moly spray-on, oven-cured products, especially for restoring older (WWII) military firearms in my personal collection. I would like to restore the exterior finish on a 1943 Reising M50 .45 cal submachine gun which I fire only occasionally, once or twice a year, and would like to apply a Teflon/Moly finish to the barrel (26 cooling fins and compensator). Would this finish withstand the heat generated by full automatic operation? This particular weapon currently has its original, very worn, Parkerized metal finish.

Answer: The darker the finish the more Molybdenum in the product, however I believe only the dark Parkerize gray in Gun Kote will withstand the heat. After curing the finish will withstand around 900 degrees without color change or softening. We are also testing some air dry finishes at this time that will withstand 1200 degrees but they are some time away from acceptance.
-- Monty Crain, Brownells Gun Tech


Question: I have a machinist who is chambering a machine gun barrel with the 308 win reamer you sold me for a Savage 99E. He says he is having a terrible time controlling chattering due to the hardness of the barrel. Is there anything he can do to control this? Is there an oil made for that particular problem? Do you sell anything for that problem? I love the rifle and shoot it a lot as well as hunt with it, so the thought of a hard barrel was appealing because of barrel life.

Answer: Once chatter has been established, it is very hard to eliminate. The best way is to check how deep you are into the chamber and see if you can clean up the chatter marks with a drill and start back at that point and give it a go again. If you are too far into the chamber and don’t have enough material to get a fresh start, you may have to set the barrel back, clean up the chatter with the appropriate drill and then start over. Keep in mind that some machine gun barrels have chrome lined chambers and bores and a standard reamer will not touch it, it will require a carbide reamer to handle the chore of cutting through the chrome. Other machine gun chambers are stellite and will require special tooling as well. If the reamer cut the Savage barrel without any problems, it would lead me to believe that there was nothing wrong with the reamer before starting on the machine gun barrel.
-- Mark Hudson, Brownells Gun Tech


Question: I have a Colt 1911 MK IV series 70 Gold Cup NM SN 70N75XXX with a Elliason adjustable rear sight. Problem is the front sight broke off.

There is no dovetail and the stud is broken off into the slide. Any tips on how to remove the stud and what do I replace it with? The rear is plain black - no dot.

Answer: The style of sight you have is a stake on, I typically knock the tenon (the portion remaining in your slide) out from the underside using a 1/16" punch. You might replace it with (#584-007-446).


Question: I punched out the tenon (the only part left) out of the slide. The remaining piece is about .125" long, .055 wide and .095 tall.

After the tenon, there is a tapered slot to go from the top of the tenon to the bottom of the slide. It is about .345" long and also about .055 wide. I cannot get the depth. I cannot determine from the part description if this is the correct part with the wide vs narrow tenon.

Answer: Your sight is a narrow tenon, i.e. (#584-006-145).


Question: Do you have any advice on installing? I was planning on inserting with a lock tite or JB Weld dab and then trying to stake over from inside the slide (with a brass hammer and steel punch) and then polishing fairly smooth. The tenon I punched out was nearly impossible to see from inside the slide which leads me to believe there was not much of an upset of the tenon. I'm not sure how hard the tenon is.

Answer: Installing a stake on sight can be tricky; there is certainly a learning curve to getting a correct installation, it is basically a cold forging operation. We have a specialized punch for staking the front sight (#080-817-000). The installer must estimate the correct amount of tenon on the sight in relation to a correct bevel on the inside of the slide and adjust as needed. My technique is to lay the slide on a massive steel plate sights down. I than shim the rear sight until the front is laying perfectly flat on the plate. It is typically a 2 man job (one holds the slide while the other peens). If my assistant is missing I drape a shot bag over the rear of the slide while I peen the tenon into the countersink in the slide. The Kuhnhausen Shop Manual (#924-200-045) describes the procedure and has a few photographs.
-- Eric Kiesler, Brownells Gun Tech