Using rifle bullets as plug-gauges?

I don't typically go for military-surplus rifles, but I have heard of others using this method to sift through piles, by-the-muzzle, testing the muzzles with bullets as a go/no-go gauge, ditching the rifles with badly worn muzzles and taking the ones with the least erosion as the 'good ones'

Especially good if you're at a gun-shop where there is a good selection of bullets that you can measure...

Cheers
Tinker