Author Topic: Cobra 38 Sp. derringer observations  (Read 764 times)

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Offline trotterlg

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Cobra 38 Sp. derringer observations
« on: July 18, 2009, 07:14:32 PM »
I aquired a very lightly used Cobra derringer (38 Sp.) in very nice condition.  The previous owner mentioned that he had a problem in the past with light hammer strikes but had sent it back to the factory to be fixed.  Cannot tell if this is true or not, but I took a close look at it to see how it functioned.  I do not call my self a gunsmith, but have done a lot of barrel work and custom barrels for H&R Handi Rifles, so I do know about fireing pins, head space and a few other little items.  On this gun, the top barrel fireing pin had a protrusion of about .090 and the bottom pin about .030.  After takeing them out they both measured within about .004 of each other, however the bottom pin was about .020 smaller diameter than the top pin, the hole through the breach plate was the same size for both barrels.  I will say it is not easy to measure the fireing pin protrusion on these little guns, so I may be off by a few thou.  The parts list shows different part numbers for top and bottom pins, however it is hard to believe the diameter is the difference.  Also the chamber was cut deeper in the bottom barrel than the top which added to the light strike issue.  Long story made short, I made up a new fireing pin for the smaller diameter too short bottom pin and shortened the top pin, now they both have about .065 protrusion which is more than I would do for a rifle, but is less than the factory had on the top and more than they had on the bottom, they both now shoot and don't pierce the primers and set them off 100% of the time.  From some research on the web, it seems this is somewhat of a common problem, if you have one you may want to check the pins, I think a build up of tolerances in the design may get to the point that they are not reliable because of the pin protrusion on one or both barrels.  Other than this problem it seems to be a very simple functional gun, it is heavy, but it does shoot every time you pull the trigger (now).  Just some observations of a very simple gun.  Larry
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