DD

Thanks for the info, a pity things aren't quite as straightforward as I had hoped

What are the known weaknesses of the thin sided Martini Cadet?
Seems the preferred actions all have thicker sidewalls and a reinforce bulge around the barrel tenon seating area...
I tend to steer clear of the Sportco Martini conversions, as the action side walls were all surface ground (~.030"+ per side) to remove rust pits and proof marks, Govt stampings etc before reblueing... which further weakened them. They also fitted an annoying cross slide safety just behind the trigger.

In Australia there's two main conversions I've seen... the quick'n'dirty way which involves chamfering out and TIG welding the off-centre RF firing pin hole at the end of the falling block. Danger of overheating and distorting/weakening the block if anything other than TIG or MIG is used.
Facing off flat and re-drilling (from the rear to ensure concentricity) and remachining a smaller central CF firing pin hole. New or replacement CF .310 firing pin then reprofiled to match the new hole ; and

The 'proper' way:
Counterboring and a threaded bushing made up (similar to the refinished blocks on a Martini Enfield .303 factory refurbishment), new or replacement CF .310 firing pin then reprofiled to match the new hole.

Do you have any links or recommended books on the M12 or M1215 conversion please?

Cheers

TM