Sig P320 80% Frame Rail Calculator
In doing the Sig P320 80% Build I had to do some math to cut the frame rails down to size. Yes, the top plate of the jig got me close but I still needed to remove some additional metal. I created this calculator to help me with the math based on my measurements to fine tune the rail size based off of a factory Sig Fire Control Unit.
To use this calculator measure your front and rear slide rails after you have trimmed them down to the size if the top plate and plug them into the highlighted area of the calculator and it will calculate how much you need to remove from the frame rails.
Choose which frame rail to file down and trim it to that size. For instance, Side 1 Front Rail measurement after material removal, this can be either the Front Right or Front Left. Trim that rail until you reach the measurement below before moving to the other rail.
These measurements may not get you exactly to the size you need but will allow you to get close enough to do some final tweaking to match your slide.