I received my first over/under shot gun today. The customer said he had a bad firing pin, lower barrel did not fire. I don’t mind admitting I am intimidated and excited! I remember feeling the same way when I first walked in to the ring years ago I had great teachers and actually became pretty good, and intimidation was gone. I feel the same way about the knowledge that you gunsmiths offer your time and experiences, just a FYI thought you should know. I took and tested in the field. If I use the selector switch everything works fine, when I don’t use it I have to jerk the gun backwards to get the inertia block to engage the bottom barrel and then it fires. I took the stock off, checked the movement of the block, it moves in all directions. Is my thinking right?
It has been a long while since I worked on one. Check there is enough room behind the inertia block for it to swing. Trying leaning your shoulder harder into the stock when it fires. -TL
Question Follow Up
TL thanks, I took and went slow and dissembled the inertia moving components, cleaned them up best I could without removing them from the firearm. I noticed the inertia block was moving more freely. Put it together, went and shot 2 shell that’s all I had with me, the gun performed perfect.
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Good to know you got it fixed. Now you won’t feel as intimidated next time you see one, will you? You are doing well. -TL
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It is a good idea to check the rod that secures the stock to the receiver. I had a Citori with the complaint of the bottom barrel not firing. It turns out that the stock rod could be screwed into the receiver far enough to interrupt the travel of the inertia block.
The correct spring on the front of the lower firing pin is important as well. A1
Reply
Thanks for tips A1–it turned out that the trigger piston and spring was filthy and giving the inertia system a lot of hang time, if you know what I mean, Tore the complete gun down. Gave it the TLC it deserved, off to races again. Gained some great experience and some knowledge of function and design. Intimidation GONE!!! 😉
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Sounds like it was on the edge of working or not working and your cleaning tipped the scales toward the working side. I would advise you to weaken the inertia block spring (spin it) so it doesn’t take as much inertia to have the block move rearward. Also polish the sear tails where they engage the inertia block so there is less friction between the inertia block and sears. That way they will want to slide across one another easier. Ken
Question Follow Up
Thanks Ken. The gun is gone, but I will sure remember that if the gun was to come back sometime in the future, and also to pass on to our fellow gunsmiths when needed. I have a question–just by spinning the spring would it change the pressure, Also I would have worried about the block returning soon enough like I was taught.
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For discussion and demonstration of lightening springs by spinning, see Marlin Smooth & Tune & Trigger Job in GunTech & S&W DA Trigger Job in GunTech 70. Jack
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With a lighter spring forcing the block forward it won’t take as much inertia for the block to move rearward. Also the lighter spring will mean the block stays back longer before it overcomes the mass of the block and will return forward. As far as return there shouldn’t be anything preventing the block from returning forward so a light spring is not a problem. Ken
