Way to go! I've shimmed a few barrels and they haven't failed me yet!
you do not have to glue the shim in place. you can just wrap the pin on the frame and remove it when going to another caliber. brownells makes stainless steel shim stock in a variety pack that works perfectly, cut to fit, every barrel fits like a bank vault!
I've done the same with a couple barrels that locked up fairly tight, but had just the slightest amount of play, maybe .001, and it worked fine, just completely wraping the pin with the shim stock, as I tried to bond with epoxy and the fit was too tight to lock up.
The nice thing about the feeler gauges is you can leave them attached to the gauge and using a screwdriver and pressure from your thumb, place the screw driver next to the gauge and while applying pressure to the guage blade against the screw driver and with a pulling motion you can put a perfect curl into the feeler blade and it will hold a memory but remain springy. Do that a couple times and the curl gets tighter, and then just use a pair of scissors to trim it to fit all the way around the frame pin, making sure it doens't overlap itself, which will cause a bad fit. I've got several preformed extras in my drawer, and when I get a barrel I just pop the shim on the pin and try out the fit. It's either a go or no go!
Also works well if you decide to later sell the barrel and still have it in excellent condition and not tampered with.
I think where you need to actually bond a shim is when you have a lot of slop or side to side play, and you have more space for the epoxy to form and bond without getting squeezed out!