Hi, Please excuse the ill formed terminology of this note. But I was surprised to learn something about Valmet412 combination guns. I have a very early 412 in 12 gauge and 308. And a little newer 12/222. I was surprised to learn that the barrels do not interchange. One of the guns (I forget which now but if anyone cares I could find out) will accept both barrels. But the other will not. Upon examination, there is a difference in the base of the receiver near the back of it on either gun. The 'central piece' on one is wider than on the other. I did read somewhere long ago that the early 412 guns had been lightened a little, and a second generation 412 was created Not the 412S, but two versions of the 412. Anyway, this may be worth knowing if acquiring new barrels. I expect the experts on this forum knew that already.