Are these suitable actions for building a custom on. I know they have a three prong firing pin but I thought I read somewhere that they could be replaced.

Thanks,

Mike

I've seen the cartridges (many years ago when I was collecting) and the way the firing pin is made it is like the letter E with two long prongs top and bottom and the actual firing pin being shorter. The case had a deep groove around the head to clear the outside prongs. Perhaps the outside prongs could be merely ground off. Additionally, the case was a bottleneck shotshell with a base of about 14 gauge and the neck of about 16 gauge (these may not be correct guauges but you get the idea). This way even if the gun was modified it still required the special shells which were for police/military use only and tightly controlled. A rebarrel would solve this problem in a hurry. I've seen those old guard rifles for sale in SG News and would anticipate that they would in very poor condition.

I would think that you could bush the firing pin hole in the breech block and make a firing pin to fit and the barrel and cahamber to just about any caliber of the same pressure of the .303 Brit. In Frank DeHaas' book on gunsmithing singleshots, he talks of bushing a Martini Cadet for changing from rimfire to centerfire and viseversa so I would think it would be possible. I would want a small dia. firing pin for modern ammo anyway.
Just my two cents.

I have a 45-70 built on a Martini .303 action. This is a better action than the shotgun ones , simply because you don't have to do any breech face work to get rid of the two extra pins - which were cleverly put there so you had to buy the ammo from Mr Greener.
I would also suggest using a small .310 martini Cadet action as being better still than the .303 , these are made of better quality steel and are also more attractive to look at . Australia and New Zealand still have lots of martini rifles , so you should be able to find a complete one , or just an action without too much trouble.
The suggestion of redrilling the bolt face on a .22rf action to use centrefire ammo is possible - I am doing just that to a target rifle action to convert to .22 Hornet , but it is a hassle and best avoided unless you have all the workshop equipment to do the job yourself .

just my random thoughts , good subject though....