Make a simple pin gage from the back end of a drill bit. the go pin is sized to just enter an LPP pocket and it wont enter an SPP. A nice wood handle on the end and leave the pin bout an inch long. A piece of 3/8" or 1/2" slightly tapered with radius on each end is comfortable to hold. Drill the center hole for the pin and form handle then glue pin in handle. A nice oil finish.