you have the basics correct.  Breach seating Martini actioned rifles can present "issues"  I have several and a couple I'd really like to use more often that way.
  In a stout enough action one might be able to carefully insert a lubed SOFT alloy bullet and than use a plugged dummy case with an adjustable length plug to push the bullet into the rifling by finger pressure or a safe "pusher" and then using the lever to close the action and do the final seating.
One might want to round or bevel the top lip of the block slightly so that in closing the action it cams the dummy into the chamber while pushing the bullet into the lands. On small diameter soft bullets  that would probably be adequate. 

  Some have used a mechanical seater on the martinis which have the block hinge-bolt high on the back edge of the receiver.  the fabricate a replacement hinge bolt the protrudes on each side and  bifurcated seating lever is pivoted off the protruding bolt ends.  Others have added a stud to the side of the action that a lever can work off of.  On my 7.5x55mm swiss free rifle I have used a push seater that has a stout doglegged shaft that has been been headed and bent and then ground and polished to fit the feed ramp space. 

  I have seen and carefully examined a mechanical lever type that has a machined steel case as part of the lever,  the case has an enlarged rim on the lower edge that engages the slight gap between the front top edge of the block and the lower rear of the Barrel breech and frame when the action is fully opened.   Its a masterful and time consuming piece of creative design and custom manufacture---and the maker said he'd never do it again.  it would require a lot of machinist skills, and mills, lathes, and a welders.  plus a lot of trial and error hand fitting.   I talked to a couple men who have made a lot of Breech-seaters and none were willing to take it on.

  I think with a euro-schuetsen martini that has the tang-boss for the diopter sight I think a square steel peg could be carefully filed out that would fit into the diopter base opening and then used to anchor the breach seaters pivot. I may try that at some time with one of my martini schuetzens, but the Swiss rifle I want to shoot the most has no diopter sight base to work off of;  so I'm using the push-seater for that rifle.

One other thing. How far you breech seat the bullet ahead of the case will vary a little with each rifle but a good starting place is 1/16" ahead of the case mouth.

40 Rod

When one is referring to seating depth it is really dependant on how the rifle is chambered and the actual deminsions there of. A good example being the eight 25-35SS's we are shooting out this why all have 220 thousandths of freebore and 1/16 ahead the case just will not work. With that being said the only reliable and correct way to figure out the correct seating depth is to seat a bullet, push it out and see where it engraves. Most here go well beyond the proclaimed 1/2 way through the baseband and we engrave or bullets complety through it or just barely shy from doing so for the very best in competitive accuracy success. I really wish the 1/16 ahead of the case recomendations would somehow go away it can be extremely missleading to say the least for some if not most and it can lead to extreme disappointment and continued frustration. 

JLouis

I might add John Merz gave very sound advice for rifles that were designed and chambered for breech seating and in no way was I trying to challenge his knowledge in anyway! I was only trying to give sound and honest personal advice for those that might not be such as mine and possibly others as well and my only true intent. I have just found it best if not knowing to seat a bullet, push it out and a take a good look at it and go from there. John Merz is a dear friend of mine and I can only hope he undertands that is all I was simply trying to point out and not to purposely take anything away from him.

JLouis

M-79:    "hard" might be too strong a word.   It can be done, some ways are easier (or harder than others)  If you are talking about a BSA "cadet" action at least that is a known quality and form.  the next step is knowing what the cartridge/caliber you are contemplating.  If it a smaller calibre and you are using a softer alloy (and I'm not sure where the break point is, alloy-wise)  a push seater or and adjustable plugged case (or trying a case with different length fixed plugs) and some sort of curved push rod (to accommodate the curved access of the feed ramp on top of the breech block) it can actually be pretty simple.

  Its when you are trying to come up with a mechanical compounding leverage seater you'd probably need with larger and harder bullets that creating a breech seater can get more complex.

Really JL?

You shot the winning score at your last Modesto match:

LOUIS          492/12   28-35SS

I read that as a pair of 246 6c

My last score was a 246 7c

Since I changed to the Russ Webber system, I can now shoot as high as 249's at Spokane. What is your highest match scores?

Frank

Wayne, I'm sorry but, my first post was to that end. But, it seems that when ever I post some usefull info, JL always comes back with some demeaning post about what I know and my abilitys. These are personal attacks and they aren't allow on this forum. Note that he didn't direct his answer to John M's post, the way he did mine.

I do have a competitive sprit and I just can't lie down for that type of treatment. If he did that to everyone, it might be different but, he only does it to the people, that disagree with him.

There are many ways to "skin a cat" in this sport but, not for him, he is the only one that knows how to do anything!!!

For standard BP chambers, the 1/16" setting, will work, to get someone started and I don't think he is looking to shoot 250's or win matches right now, just get good grouping to what ever the OP standard is for that.

Frank