New discovery involving "FTF's"

[wobblinwheel]

After owning my Colt M4 Carbine for a few years, AND reading reviews and watching UTube videos on "Tactical .22's", it has become awfully clear that one of the biggest problems that people have with these guns is FTF's or "misfires" as I call them. This became especially aggravating to me after buying a box of Winchester "M22" bullets from Wally=World (1000 rounds). They cost $45 a box and seemed to be a good deal, since I was in the mood for some open-sight, rapid-fire shoot'em up. Well, things went ok until the gun got a little "dirty" and the FTF's set in (as usual). I decided to pull the lead from some of the many "duds" that I had accumulated, and I discovered that the POINTED (chisel-like) end of the firing pin was "crumbling" the priming compound instead of "squashing" it (as it should). Anyone knows you have to SMASH the primer on a rimfire, not "punch" it with a pointed object! Then, under magnification, I noticed the strikes on a handfull of my spent cases varied from light pricks to deep gouges! No two the same. After disassembling the bolt, I discovered the problem: an "INERTIA" ACTIVATED FIRING PIN! I thought these were only used on guns with exposed hammers to prevent accidental firing with the hammer lowered onto the firing pin! The only FORCE behind the firing pin is the INERTIA from the impact of the hammer transfered to this little lightweight, stamped-out, POINTED little firing pin! I figured the chisel-point on the end of the pin was so it could put some kind of a "dent" in the rim. BUT NOT WHEN IT GETS DIRTY!! I remember as a kid, our .22's NEVER seemed to misfire. They had nice flat-on-the-end firing pins that were driven into the cartridge by the unstoppable force of the HAMMER! Every strike was big and DEEP! How many of these relatively unreliable brands of rifles have this setup? The firing pin in these guns is too LIGHT, has a SPRING pushing in the opposite direction, and the hammer mass and velocity is inadequate to do the job. Even minor variations in rim thickness can cause big problems! In case you don't know it, consistent ignition means consistent accuracy as well. Has anybody tried a different (longer) type of firing pin in these things? The pin needs to be FLUSH with the face of the bolt (no spring needed), travel mechanically limited as not to strike the cartridge TOO hard (and not to damage the breach from dry-firing), the striking-end should NOT be pointed, just flat. I think I'm going to try to make one, if I can find the right kind of hardened steel. Any ideas? I think this type of firing pin would be the equivalent of TWO of the current design (striking force and contact area). I know it will work, I just gotta build it.......

[Tal]

Excellent report on your findings. Waiting on the results.

[techmike]

Mike, I'm confused.  :o  Please correct me if I am wrong, but I seem to remember an older post where you modified your firing pin, and/or spring, on this rifle and FTFs where a thing of the past.

FYI, the reason for the spring on the firing pin is to inhibit forward movement of the firing pin when the bolt slams forward on a live round. The spring is utilized to overcome the forward inertia, thus preventing a "slam fire".  My Colt M4 is all stock parts in the bolt and it has no problems with reliable ignition. Getting close to 8K rounds through it.  :thumb: