Will the Hornady Comparator fit properly on an older RCBS dial caliper ? Searching for a system to duplicate bullet seating depth of prefered loads along with adjusting sizing die for a shoulder bump but am not sure whether the Hornady or Sinclair Comparator would work better with my existing RCBS dial caliper, also curious how they both compare to the RCBS Precision Mic. The fact that the precision mic is caliper specific if fine if its easier to use and more acurate. Thanks in advance for responses.

I don't know why your calipers would work any different than mine. I don't know nothing about the precision mic.

The Precision Mic will work okay for headspace work, but it does not provide you with any absolute measurement. You can detect datum line length changes due to firing and resizing, but the info you get is all relative. IIRC it also comes with a bullet comparator device and it will give you relative data as well. It's real easy to use, so there's that. No caliper is needed with this tool.

I've used the Hornady bullet comparator system since it was a Stoney Point product. I've used it with three or four different calipers, no sweat. I have not used the Sinclair product but I can't imagine how it would be much different from the Hornady tool.

One thing I figured out early on about the bullet comparators...you can use one to look at headspace changes as well. Just pick an insert that rests near where you think the shoulder datum line should be and you can observe relative headspace changes due to firing and resizing, just like you can with the Precision Mic. You don't have to be precisely on that elusive datum line.

Since a caliper is useful for a lot of purposes in handloading, I'd advise anyone starting out to consider it an essential tool. Everyone should have and use one, and since that's the case then the Hornady or Sinclair accessories make a lot of sense. Another advantage is that they are not specific to any single cartridge like the Precision Mic is.

The only other thing I would add is that for finding the 0-to-lands seating depth, you do not have to use the accessories available for the Hornady system. You can get by just fine using a fired case with a split neck and the comparator, but there are pitfalls and a bit of a learning curve involved. It's not that hard, it just takes patience and cranial utilization. That said, there is nothing wrong with the extra tools Hornady offers except the need for more stuff for each different cartridge and the associated expense. If you're like me and have every available nook and cranny stuffed with tools and accessories and components, the split-neck method makes more sense.

Buying and using a Hornady Comparator was/is an eye opening experience. I wish I'd of looked into it the day they hit the market.

kwg

@MickinColo I need to come to your house and learn from you. I been trying to understand the whole headspace bumping the shoulder back.. .What's right or wrong...

Found so many videos of different ways it's sometime confusing.

To measure the shoulder bump back/headspace you need these gauges, the ones I showed in the earlier post are the gauges to measure COAL.

I reloaded for 30 years without any of those gauges and managed to figure out how to “bump” the shoulders back. They aren't necessary but they do make life a little easier.

It takes a lot of guess work out of resizing to fit your chamber.

kwg

I’ve owned my Stoney Point comparators and “Head’n Shoulder” gauges since the early 90’s. I consider them some of the more useful reloading tools I own. I have three Mitutoyo calipers dedicated to a couple comparator bodies and the headspace gauge body.

In more recent times I bought the OAL gauge, liking that too.