Threw together a cartridge overall length gage or as i call it comparator.
Works really good. Still a work in progress, prototype Actually. Instead of using a knob to lock your finding in place it Utilizes a collet.
Have found this to be very precise and repeatable over and over. Will drill and tap casings for all of my rifles. I was surprised at how much jump there is on 250 grain factory bullets in the 450 bushmaster. I cant remember the exact number. But .2 in my chamber rings a bell.
I'm making 10 of them up over the next week or so. Theres been an active interest for this tool with some of my reloading peers. They will surely critique me, most have been machinist for decades. I have some muzzle breaks ive made as well that need testing.
Will see how it goes. Still have a few things to do to the prototype.
Fun stuff...