These pictured scope, believe it or not, are all the same lens systems. You can swap out any of the ocular lens cells, into any other. The 438 lens cell is a little different but, you can slide it into any of the other scopes, you just won't be able to hold it with the others nut but, you can tighten the other cells, into a 438. If the lenses are clean, they all have equal optics. My Mossberg 7C, 8X, has a acromat objective lens but, I can't really tell the difference if I put a 4X, ocular cell in it.

The front mounts and turrets are all different and all have 1/2" clicks @ 100.

You might think that the 438's objective is different but, it's just set back more than the others. The longer tube, makes for better positioning on different rifle setups.

BTW, Gerald Kelver, liked the Mossbergs a lot.

Frank

I generalize that big game scopes should be 2X for each one hundred yards to the limit the rifle will be used, varmint scopes should be $x for the limit the rifle will be used, benchrest target is the highest power allowed by the rules.

Big game at 300 yard limit would be 3 X 2X  = 6X
Varmint at 300 yards would be 3 X 4X = 12X 

This is a guideline and not an absolute. In this case, the .22 K-Hornet would be a 200 yard maximum shot times 4X giving a scope of 8X.

Travelor, I tend to agree with you. Though I think the older "long" scopes like Unertl, Fecker, Lyman, et al look great and also look like they belong on this type of gun, since I will be mainly using it for hunting game and varmints, i will likely end up with a more moder scope, maybe a variable, but not sure.  Thanks to all for the great input.  First I would like to find a good gunsmith, with experience in Martini's. I would like them to take a look over, see how the firing pin and bushing are, maybe drill the back of the receiver so it could be cleaned from the breech end, check the trigger mechanism and see if it could be improved. Though the trigger seem pretty good, smooth, crisp, no pretravel, don't know the pull weight. hard to judge as my two other hunting guns are a Ruger No. 1 in 45-70 and a Remingtom 721, 30-06 with a canjar trigger.

If I end up using a modern scope, would it be a good idea to find one with extended eye relief so I could mount it so it would not interfere with the loading and extraction of the round.
Sorry if these questions seem off, but I have never owned or fired a martini. my Ruger is a single shot and I don't like the way the scope is on that either. But then I find that with the Ruger you have to creep up the stock to get a good sight picture, and it doesn't feel comfortable. Maybe an extended eye relief scope on that on too.