Unless you are really really needing the accuracy, it is a fine tool for the job.
If you really want to know if it is as accurate as it says on the box, you pretty much have to find someone with a set of gage blocks and start measuring them to see just how accurate the caliper is in YOUR hands. That way you get to see how the measurements fare, with YOUR feel.
In reality, it does not make much difference what the caliper reads, as long as the rounds feed, and they are all the same within reason. I'll let you determine what you tolerance range should be. But I will say, if you are expecting to measure plus or minus a thou, and are expecting to match a particular length accurately, you are probably the owner of the wrong tool for the job. Seems contradictory, but really, it's about whether the tool can be relied upon to give the correct measurement, consistently, or whether it gives the same measurement (that may not be correct) consistently.
Having a few 'test object' to use to check the caliper against, so you have more than just the Zero point to go by, is one way to see how accurately you can measure with the tools in hand. Whether those test objects are precision ground pins, gage blocks, setting standards from a micrometer set, etc, or simply a part that has been accurately measured with known good tools. If it is actually pretty close to the range in size of the part you are about to check, so much the better.
For what you are using it for, though, it's just fine. Lyman and RCBS are happy enough to put their stickers on cheap Chinese calipers, and charge much more for them.
If you want to test yours (and your measuring feel), grab one case, measure it, write down the number, put it down, pick it up and do the same again a few times in a row. See what you get for variations. Do it with the numbers facing away from you as you measure, so you do not adjust pressure to get the number you expect.
Oh yeah. look up the SAMMI specs of your cartridge and chamber. Comparing the min and max cartridge and chamber sizes can be educational!
Cheers
Trev
If you really want to know if it is as accurate as it says on the box, you pretty much have to find someone with a set of gage blocks and start measuring them to see just how accurate the caliper is in YOUR hands. That way you get to see how the measurements fare, with YOUR feel.
In reality, it does not make much difference what the caliper reads, as long as the rounds feed, and they are all the same within reason. I'll let you determine what you tolerance range should be. But I will say, if you are expecting to measure plus or minus a thou, and are expecting to match a particular length accurately, you are probably the owner of the wrong tool for the job. Seems contradictory, but really, it's about whether the tool can be relied upon to give the correct measurement, consistently, or whether it gives the same measurement (that may not be correct) consistently.
Having a few 'test object' to use to check the caliper against, so you have more than just the Zero point to go by, is one way to see how accurately you can measure with the tools in hand. Whether those test objects are precision ground pins, gage blocks, setting standards from a micrometer set, etc, or simply a part that has been accurately measured with known good tools. If it is actually pretty close to the range in size of the part you are about to check, so much the better.
For what you are using it for, though, it's just fine. Lyman and RCBS are happy enough to put their stickers on cheap Chinese calipers, and charge much more for them.
If you want to test yours (and your measuring feel), grab one case, measure it, write down the number, put it down, pick it up and do the same again a few times in a row. See what you get for variations. Do it with the numbers facing away from you as you measure, so you do not adjust pressure to get the number you expect.
Oh yeah. look up the SAMMI specs of your cartridge and chamber. Comparing the min and max cartridge and chamber sizes can be educational!
Cheers
Trev
