I have been playing with a new G20 and must admit the concept raised here is interesting. I dumped my G27 (obnoxious little $%&#@), maybe Ian bought it.... it was on consignment. Proceeds went towards the G20, much more pleasant to shoot than the G27 ever was even when shooting light loads. Here kitty kitty, no not that, the G20 was a pussy cat.
Now at the risk of causing some of you to reach for your nitro tablets, I did try some 40 S&W's through it. I have read numerous posts on the subject, they ranged from that it is fine i.e. 38 Spcl in 357 Mag, to doing so was a crime against nature, or worse. No need to hash that here it out further, that horse is dead. Anyway it gobbled them up and spit them out faster than mulberries through a duck or a goose, so in a pinch, yea it will work for added flexibility. They fed and were captured by the extractor when striped off the magazine just like a 10mm round.
I hear gasping from some.... relax, I picked up a 40 barrel for the G20. Deep breath now, in nice and slow, now exhale, one more time.... in.... out.... in..... out... in...... feeling better? Put your feet up, breathe, breathe, think about $10/M primers, COWW free for the taking, and $5/M gas checks.