I managed to snag a Nanuk 915 case for sale and wasn't able to find any good handgun foam inserts for it anywhere, so I figured I'd reach out to Cobra Foam for a custom order and I'm glad I did. The foam is very solid and fits in the case like a glove. And the actual slots hold my handguns and mags perfectly--the largest handgun being a Glock 19X, the smallest a 9mm S&W Shield.
I'll definitely be buying from Cobra Foam, again.