Old Salvimar Predathor, couldn’t reload after a shot.

Yes. Just take off the Salvi piston and install a Mares. Just make sure you order the 13 mm piston.

This one:

Plastic pistons today are generally composed of two types. There are pistons with a machined plastic body where the metal mushroom tail is a separate item screwed and glued into the plastic body and often carries a sealing ring in addition to those located in grooves machined into the plastic. The other type is the moulded piston where the molten plastic is injected into a moulding die with the metal tail already clamped in the die. The metal tail has inner flanges that the plastic flows around to embed it permanently in the plastic body and only a metal shank emerges from the plastic.

Mares pistons are moulded and have a ring of tiny bumps on the piston nose where it aligns on the shock absorber anvil, so that definitely confirms that they are moulded. Interestingly when Omer copied this idea they had the bumps sit on the anvil which is a recipe for breaking something, they should sit in the aperture, not on the anvil shoulder, although the gaps thus created can let trapped water out in vacuum barrel guns (as there are no muzzle ports).

Machined plastic pistons can have stresses created depending on how quickly that they are churning them out and this may account for heavily ringbarked pistons snapping. Ideally the groove bottom should have radiused edges and not sharp corners. The idea of these annular troughs is to hold grease and reduce piston weight, but oil lubrication in the gun makes this unnecessary and the weight reduction is trivial.

Moulded pistons should carry no stresses once the moulding conditions are fully sorted out. Pelengas moulded pistons busted until they figured it out. Mares has made their pistons of plastic for many decades, but I don’t really like their ringbarked pistons. There may be an argument for grease trough pistons in “dry” pneumovacuum guns, but Mares don’t make any.

Divestock sell Mares pistons https://www.divestock.com/mares-piston-assembly

stefpix said:

Thanks. The do not ship to the USA. I can ask the distributor. Next time I go to Italy to see my family, I will stock up on some parts. The mark up and availability in the USA is a drag.

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I totally agree. Sometimes is cheaper to buy from an Italian store and pay the shipping than buy in a USA store. Crazy!