Ask The Gunsmith with Bob Dunlap

Dunlapby Master Gunsmith and AGI Instructor Bob Dunlap

In this video, Master Gunsmith Bob Dunlap answers two questions from readers. In his own style, Bob talks about removing a Cutts compensator on a Browning A-5, and then goes on to explain how to make a starter punch for those really stubborn pins. Is there anything about gunsmithing Bob doesn’t know about? I doubt it!


4 Responses to Ask The Gunsmith with Bob Dunlap

  1. He is ALWAYS right on ! Too long a punch at small diameters on a stubborn object will most become an angle punch. Short delivers greater force on the pin or whatever you are working on…..GOOD TIP BOB

  2. I learned the necessity of concave end starter punches when faced with any variation of the Colt Mustang or Pocket Nine trigger pin. Sig P238 & 938 are identical, as are similar Kimber and several other copies of the old Colt 380 design) If you use a flat tip, the rounded end will flatten causing the end to spread out and grip even tighter.

    BTW I have found on some of these little guns that the pin hole on one side of the frame is just slightly tighter than the other side. If it seems too hard to drive one way, try the other way.

    Available sets of punches seem unavailable in this diameter. So I made mine using a 1/4 rod and broken off drill bit in the right size.

    But how to make the concave end? I have a lot of diamond plated burrs for Dremel and similar tools. Used ball-end one of close diameter to match the radius of the round-ended pin. Chuck the punch blank in my lathe and turn at moderate to fast RPM. Hold the spinning ball bit roughly in the center, and it quickly cuts a concave cavity. Self centers, too! (If you don’t prevent it)

    I’ve now made several punches using old drill bits and steel rods. I can make the concave end in about 10 minutes most of which is set-up time.

    What was implied was to make the punch short….very short! All you need is 1/16 or so just enough to get the stuck pin to start moving. Then apply Kroil

    ALSO BTW: these guns ALL seem to have plastic triggers (again copying the Colt design). I’ve had broken ones in my shop. There are good metal replacements, some curved & some straight, and some with over-travel adjustment screws. I’ve never had a customer turn down replacing their trigger! Mainspring replacement is fst and easy, too. And smoothing/lightening the pull is very easy, giving great improvement in shooting performance. Sig 938 one-ragged-hole groups at 7 yds are possible.