Not much to add to this comment. It pretty much sums it up.

Know somebody that had a 2 3/4" over and under opened up to 3". Also know a couple of people that have 2 3/4" rem 870 and put a 3" barrel on them a shot 3" like a single shot for turkeys. They have to pump real hard to eject the shell or some times have to cut it out. They mainly did this when 3" guns.where not the norm and most shotguns where 2 3/4 and they got the barrel cheaper then a new gun. I would not recommend it but they never had a problem.

I would hope nobody in their right mind would recommend doing anything like that and they certainly were having a problem short of a bulge if they had to pump it hard or cut the shell to eject it. Why risk life and/or limb doing something foolish like that?! I have a 2 3/4" chamber in my "like new" Model 1200 Winchester that I bought back in 67 and kill birds just as dead with it as guys using these big 3 1/2" shoulder bruising bangers!

I have seen them do it it and their is no bulge in the barrel they have done this hundreds of times. I personal have never done it or recommend it but seen it and their is no problem. I have shot their gun at turkey shoots with low brass 2 3/4" shells so I have looked at the barrel no problems. The reason they have to pump hard or cut the shell out is the empty shell is larger then the receiver opening. Again I DoD not recommended it but I have seen it done and their is no problem with the barrel. The barrel is a 3" chamber again, they don't shoot 3" in 2 3/4" chamber barrel.

I understood what you meant regarding the ejection problem, but what I worry about is people that don't know much about guns might not read exactly what you mentioned about the 3" barrel and correlate that with the OP statement about putting it into a 2 3/4" chamber. Many people just don't understand the intricacies of chambers, etc. For instance, I read yesterday where a guy walked into a gun shop and asked for a box of shells for his .270 Remington. The guy behind the counter handed him a box of Winchesters and he told the guy no, he needed shells for his Remington! There are many out there like that who don't have a clue! Another guy at a gun range asked an instructor how to unload his semi-automatic rifle because he was paying a lot for all the shells he was shooting to unload it when he got done hunting! Yes, there are some real winners out there and I wonder every day why there aren't a lot more accidents and injuries than there are. Maybe there are and they just don't get reported.

Funny you said about the 270 remington, up in cabelas at Hamburg their was a used customized cz 24 that the barrel was stamped 270 remington.

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Geez, I wonder why a GS would do that unless it was a complete home job, but a guy that could do that should know how to mark it.

It looked like a nice rifle, put together right not some home gunsmith.