Need some advice on how to raise the height on the firing pin impact point on a Martini Cadet. The rifle has a BSA rimfire breechblock and was barreled for 17 HMR. Getting about 25% failures to fire, shells will ultimately fire on a second or third attempt. I am assuming the breechblock needs to be raised about 0.010” to accommodate the larger rim diameter of the 17 HMR. The dent from the firing pin looks adequate. I have seen other posts talk about drawing the horns on the lever as described in the Martini Armourers Handbook. Can anyone provide a description of the proper way to go about this? I suppose the other option would be to add some weld to the top of the horns and re-machine them to the proper height. I am not much of a welder so I would prefer not to go that route if possible. Thanks in advance for any advice.

It sounds like the bushing was not installed on center you may have to re-bush the block to get it on center. Might look at the firing pin, to see if it has been reduced to the right diameter I normally go to 5/64 with .065 protrusion. Also check and see if it is the correct firing pin spring lots of times they are cut to reduce the trigger pull.
Hope this helps.

The breechblock has not had a bushing installed. It’s a 22 rimfire breechblock from a BSA Martini. Firing pin is also for a 22 rimfire. Firing pin spring is new old stock. I recall reading somewhere that when converting 22 rimfire Martins to 22 Mag you can get away sometimes, but not always, get away with out modifying the firing pin location to accommodate the larger rim diameter on the 22 Mag. I am thinking this is the likely issue

oops I missed the 17 HMR it being a rimfire sorry sometimes my eyes are off kelter. I think you are correct in thinking it may the difference in diameter or location

No worries and thanks for the response. The question still remains how to go about adjusting the breechblock upwards about 0.010”

Thinking out loud here. If you add height to the horns you are in turn rotating the breech block upward (because it's a tilting block on a pivot). Wouldn't the face of the breech block no longer be perpendicular to the bore after doing that? Cockeyed breech support of a rimfire can be the kiss of death accuracy-wise.

I know this is a Rube Goldberg suggestion, but on all my Martini's the firing pins are quite large.

On my .22, I cut the main spring shorter and sharpened the firing pin into a vertical wedge. This was done primarily to retain reliability while reducing trigger pull quite a lot, but I am wondering if the second part of the process might not solve your problem.

Seems to me making a new firing pin might be much easier than lifting the block. Perhaps a firing pin that strikes on a smaller area right at the top would be worth trying.

Gonahhh - you are technically correct. However adding 0.010” to the horns should have basically zero change to the angle of the breechblock face to the cartridge head I believe.

Peter - I read somewhere that changing the firing pin nose to a chisel point was pretty commonplace by target shooters using VSA Martinis. The same post warned that using chisel point firing pins with 17 HMR can lead to case ruptures. I assume the result of higher pressures??

This guy extended the horns by welding on a Martini Henry. Proper concept, but I am a lousy welder.

https://www.youtube.com/watch?v=hGNSUD8F2e0

I believe the Armourers Handbook is instructing to lengthen the horns by hammering the lever at the neck above the pin hole. It’s says it’s ok to raise 0.010”. It does not say if the lever has to be heated or not. See pages 32 and 33

https://www.rifleman.org.uk/In..._Armourers-1897.html

Oh the things I get myself into. LOL. Thanks to all

The lever is case hardened.

I think you would need to heat it.

But I still think making a firing pin is a worth-while effort, given how relatively easy it is and that getting it wrong carries no risk of permanent problems with the rifle.

I think the risk of case ruptures could be very dependent on how sharp you make the chisel?
But what I am suggesting you do is not really the traditional vertical chisel, but rather just biassing the firing pin nose upwards a bit by reducing the striking area.

Not to hijack this but I need someone to advise me on how to convert a rimfire one to center fire

quote:

Originally posted by Jim Kobe:
Not to hijack this but I need someone to advise me on how to convert a rimfire one to center fire

Bob Snapp bushed and modified the firing pin using a de-primer pin from RCBS

Peter, you make a good point about not damaging the rifle by making a new firing pin. If I make one that has a flatten wedge shaped end it should make a better or deeper impact towards the outer edge of the rim. I will give it a try when I have time to get into the shop. Thanks for the idea!

If it will help I have a couple of center fire pins if you might wish to experment a bit. I could send you one. Aways re-drill it for a off set pin

quote:

Originally posted by Jim Kobe:
Not to hijack this but I need someone to advise me on how to convert a rimfire one to center fire

Like Duane said. Come in from the rear and drill out the fromt of the block and install a threaded bushing. then re=drill firing pin hole and make a new pin. Its covered very will in Frank DeHaas book "single Shot Gunsmithing" I have done a number of them

Thank you Rolland. That is a very generous offer. I think I should be able to make one. Looks like a good home machine shop project. If I am unable to make one I may be back to you later. Cheers!