This is turning into one of those "how many angels can dance on the head of a pin" type discussions scholars had back in the middle ages. At this point you can make an educated guess regarding the barrel steel, but without lab results you really don't know for certain. If the data in so far leads you to believe the barrel can be welded, why not go ahead and weld them, being certain to thoroughly inspect and test for cracks etc when you're done. The barrels aren't worth spit the way they are right now anyhow.
Steve

Approach life like you do a yellow light - RUN IT! (Gail T.)