PWC
Member
I wanted to measure the “before and after” firing for my rifle cartridges, and not having the xpensive equipment to do so, I made a block that is sufficiently accurate for my needs. Dimensions are all reference only and tool is to help measure repeatably at the same point of otherwise hard to repeat points.
I took a piece of hardwood and drilled two holes with my Forstner bits (for flat bottom holes), and varnished it. One near case diameter of the head, and only as deep as the case just above the rim, the other near shoulder diameter with a thru hole to allow the neck and/or bullet of a loaded round to protrude thru.
To use the “tool” place the head in the appropriate hole and place your caliper flat on the block and take a reading. Reverse the cartridge placing the bullet/mouth of the cartridge in the other hole and repeat measuring with the caliper flat on the block.
I can take a comm’l round and measure it, shoot it and remeasure, anneal and measure, size and measure, and/or measure the reloaded round…..if I want. Or pick and choose which measurements I want/need. Also used for range pick-up.
It’s not machine shop accuracy, but it gives me a repeatable point of reference. You can also use a sharp, narrow tip marker to mark the case. I’ve found that the marker doesn’t always survive the heat of the shot.
Marks do allow "free handing" measurements after firing. Remember these are not exact but reference values.
I took a piece of hardwood and drilled two holes with my Forstner bits (for flat bottom holes), and varnished it. One near case diameter of the head, and only as deep as the case just above the rim, the other near shoulder diameter with a thru hole to allow the neck and/or bullet of a loaded round to protrude thru.
To use the “tool” place the head in the appropriate hole and place your caliper flat on the block and take a reading. Reverse the cartridge placing the bullet/mouth of the cartridge in the other hole and repeat measuring with the caliper flat on the block.
I can take a comm’l round and measure it, shoot it and remeasure, anneal and measure, size and measure, and/or measure the reloaded round…..if I want. Or pick and choose which measurements I want/need. Also used for range pick-up.
It’s not machine shop accuracy, but it gives me a repeatable point of reference. You can also use a sharp, narrow tip marker to mark the case. I’ve found that the marker doesn’t always survive the heat of the shot.
Marks do allow "free handing" measurements after firing. Remember these are not exact but reference values.
