Thread: Digital caliper recommendation ??? for comparator use

There have been a number of threads on calipers (I asked myself once). There are always people who advise you to use $20 tools. Surprising how few do the "Buy once Cry once" thing.

I'm a hunter and I struggle to get into MOA so probably am similar to you. I do a LOT of measuring. They are handy for some stuff other than reloading too. I bought a set of Mitutoyo, had to order them in and I think they cost about $280 about 5 years ago. They are still working 100% and I've only had to change the battery once. They're easy to use and always give the same result to within 0.001" measuring the same thing (you get more consistent over time there's a knack). I suspect its like rifles, quite a few meet the accuracy standard but some are more reliable durable easy and nice to use.

See: still "new in box":


This is the model. I think there might be higher grade ones with more decimal places. These ones give a reading that either .0005" or .0010" ie only slightly better than 1/1000 inch. They can read in metric or inches.


I keep them in the original packaging, with an oily rag between the jaws and a piece of "gunsmith paper" to fend off rust.


Here they are with the Hornady comparator for cartridge headspace (measure how much you've full length sized them). I also use them to measure CBTO (seating depth) to the ogive with a different insert. That is a more variable measurement from one round to another, specially if you use the Sinclair hex nut you can see at the top of the photo. The hornady bullet inserts are better to use.


Other reloading stuff I often measure are:
case length
primer pocket depth
base diameter before and after firing (I know a ring micrometer should be used for that but I'm too lazy to take it to the range and its vernier is hard for me to read).
Overall length to tip (not a datum dimension as tips vary but I do it anyway).
Primer depth check.
I don't do any neck turning, doughnut reaming, tension adjustment, bullet sorting or that sort of thing.
I'm not a F class or bench rest shooter, just hunting and a bit of gong shooting (which doesn't require peak accuracy).

So, my recommendation if you can afford them once when setting up your kit is a pair of Mitutoyo digital like these