I've always preferred the 10 over the 40. I owned a bunch of 10mm handguns back in ye olden days but got away from it, trying to consolidate into more common calibers. The 40 always left me cold. Then one of the shortages hit during the Obama era a few years back and I noticed that 40 always seemed available when 45 auto and 9mm was totally gone. So I bought my first 40 S&W handgun. I could do without it, but it's a good caliber and no reason to not have one. FWIW though, I haven't seen 40 around during this shortage, like I did during that one.