M14/M1A Castle Nut Problems
The castle nut can be a problem to install when the groves for the lock screw go just a little too short or a little too past getting things lined up for easy lock screw engagement. You want to screw the castle nut on until it seats firmly, good and firm, having done this you discover it would take too much pressure to get the grove lined up to get the lock screw in. The castle nut is very hard and can break if to much pressure is applied. Here is the easy way to get this job done and at the same time tighten the suppressor to prevent rotation or vibration, When you need that little extra to get alignment, remove the castle nut, and with a piece of 80 or 90 grit emery cloth and a shot of WD 40 put the emery cloth on a hard smooth surface, put the WD40 on, hold the nut firmly with contact end towards emery clot hand, press it down and rotate it in circles, 4 or 5 times using gentle down pressure. This will remove a small amount of material from the contact end of the nut. Clean it up and test fit again, it should advance the nut to desired position, if not, repeat until it locks up the way you feel comfortable with, firm. If you want to secure the FS to a more stable position on the barrel, you must peen the top spline... Before final installation of FS use a 1/4'' flat clean faced punch and a small peen hammer to peen the top spline. To do this peening start your punch position on which ever side you like, hold the punch approx 1/8" back from the beginning of the slot, keeping the entrance original for easy engagement when you replace the suppressor, tilt the punch towards the slot a few degrees and tap lightly ,over lapping each time until you have covered the distance the splines engage. Peen the edge over gently, then repeat this on the other side. It doesn't take a lot of edge peening to secure the FS, and you can repeat the process if you choose. Now you are ready the make final assemble, start the FS on ,with nut in place, by hand into the 1/8''unpeened part you left. Pick up the threads, continue by hand until the peening you did stops rotation. Screw the FS on the rest of the way with proper tool, not a punch. Bring castle nut to alignment and put the lock screw in and seat it snug, this screw does not hold the the FS on, it prevents the castle nut from backing off. When the lock nut bottoms out and is snug,[ and this is IMPORTANT,] back the castle nut back against the lock screw.
By Art Luppino
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