Erosion between the chamber and the rifling... kinda bad.
No, I did not intend to use the same barrel for all my shooting, just for the same caliber, which would greatly bring down the number of different firearms I'd need to "safely dispose of all that hazardous material"
. Most calibers I reload, altough in very different cases, are 223/243/270/308.
Also, as stated earlier, I do not charge anything for reloading other people ammunitions. The 10% I talked about is far more a courtesy gift than a payment. Sort of like you hunt on private land and gift some meat to the land owner as a way to say thank you. If anybody really wanted the rest of the material, I'd happily hand it over.
BTW, I contacted MCA sports and had a similar answer, saying that such a setup would result in a "light load only" rifle. They were still very polite and said that if I really wanted to give it a go, they'd see what were our options.
Just food for thoughts, if I ended up with a design like an old cap n ball revolver (let's say with only one chamber to keep it simple) with a small gap between the chamber and the barrel, does that seem like a better idea?