I don't know if the chamber insert was put in with Loctite (or other glue) or not. The one's I have seen had nice barrels on the outside, so I am pretty sure no solder was used.

I am not sure the insert would back out, since ultimately the bolt holds it in. But I suspect that if a wide enough gap opened in front of it, and it is not in there solid, it would act like the floating chamber in a .22/.45 conversion unit and back up hard enough to damage the receiver.

I was told that the conversion was done by the Chileans, with the intent of having a war reserve of rifles firing the NATO cartridge. That may be true, and a "quick and dirty" conversion like that could be useful in an emergency even if it was not very durable. (The U.S. issued low-number M1903's in WWII, knowing they could be dangerous, but a man with a gun that might have a problem is better than a man with no gun at all.)

Jim