headspacing gauge for 9mm (9x19)

[tercel89]

I always check my 9mm's by seeing if they will drop into my pistol barrel plus I'll try to make them as idienticle as factory target ammo but I was thinking of getting a Headspace gauge for easier measuring and saving time. When looking I saw the Hornady Headspace gauge that says its for 9mm in 9x19 AND 9x21 . I may be having a brain fart but the 9x21 case is longer and since the case headspaces on the case mouth , wouldn't that gauge read them differently ? Excuse me if I am wrong or confused. I thought you'd need a different gauge for each of those two rounds .

Edited November 4, 2018 by tercel89

[LngRngShtr]

not sure how that would work on a tapered cartridge, with a 3mm oal difference the taper would be off, maybe the fine print would show 2 options for sale ? 

I use an EGW 7 hole gauge I bought off of Amazon which I have verified with spent casings and a caliper depth reading is tighter and shorter than my Glock 34,43 and S&W 439 chambers so "if it fits it ships"

think it ran me $20.00