corrosive?

[jmoore]

In a semi-auto, You'd have to get at the gas tube also, right ?

Only four rifles w/"proper" gas tubes come to mind immediately- Ar15/M16, AG42b, the Hakim, and the Rashid. Of the lot only the Hakim and Rashid would be commonly fired w/ "corrosive" primed ammo, and I've never seen any problems with those. However, they were intended to be used in very arid climates, so the potassium cloride residue wouldn't be able to "attract" much moisture to start the rust process.

The gas tubes themselves in the above examples are non-heat treatable stainless steel, and are themselves likely to be resistant to rust through in the normal lifespan of the weapon.

Not a bad idea to flush out the rest of works, though, just to keep the gas port and block from pitting.

Most all other semi-auto rilfes of older design were generally set up to be "easy" to disassemble for cleaning purposes, but some are better than others- it seems G/K43s often have "rooted" gas ports- and they tend to be "overgassed" in the first place.

Note that the M1 carbine was designed from the outset to use non-corrosive primers, as the tappet system used is not field servicable. The M1 Garand was "ruggedized" by making the gas cylinder etc. from stainless steel- expensive at the time, but worth it!