Just recieved my Hornady OAL gauge at Christmas but have never used one before. I was able to achieve a consistent measurement for OAL with just a little practice but having trouble with understanding the bullet comparator. I know that this is designed to measure length at bullet ogive but the instructions included from Hornady are poor at best so I will rely on my friends here to explain this process and how it factors into setting up my dies. Also if anyone has a link to a video which shows this process it would be much appreciated.

First off you will need to determine just how long or short your throat is, where the bullet at ogive would make contact w/ lands and grooves. With my Davidson or Sinclair I use a dial caliper to then take a measurement from the ogive touching Lands and Grooves and back off X amount and go from there for furher seating of loaded rounds. Do you have a device for determining the measurement of how far the bullet is seated out to touch the lands and grooves?? The comparator is used after you have made the above measurement in order to set your seating die for more loads. Hope have not confused you, but if so, sure it can be explained more completely if needed.

martin

You attach the comparator to the caliper and rezero the caliper


then take the measurement on the ogive of the bullet

Understood so do you then set your die to seat the bullet at the prescribed measurement shown in pic #2?

It's really pretty easy. The OAL measurement that you get off your Hornady OAL tool should be measured using the bullet comparator. Forget measuring COAL as the tip measurement will vary. Then just set your seater to match the measurement, using the comparator.

Woods, I honestly don't know what zeroing a dial caliper at 1.?? would do for you. Do you then subtract the 1.?? from the 3.745? I can see doing that with a digital where you are re-setting your zero reference. Seems like some extra ciphering going on. Please explain.

Yes you can then standardize your bullet seating at the measurement in the 2nd pic. That is the closest you can come to making the bullets all the same distance from the lands. However the hole in the comparator is always .011" smaller than diameter so the comparator will hit the bullet on the ogive where the bullet is that diameter. So if there is any variance in the curve from one bullet to the next then there will be a difference in the distance from the lands, though much smaller than measuring from the tip.

The purpose behind rezeroing the caliper is that the comparator is impossible to lock into the holder and caliper jaw in the same place to the 1/1000ths of an inch and if you want your measurements to be recorded and duplicated later then the comparator needs to be zeroed. You can deduct the 1" if you want or just record the one you have as long as you do it the same way everytime. The Hornady Headspace Gauge has a 2" rezero


You need to do it the same way everytime and rezeroing will accomplish that.

quote:

Originally posted by Blackhawk83:
Just recieved my Hornady OAL gauge at Christmas but have never used one before. I was able to achieve a consistent measurement for OAL with just a little practice ....

Once you completely sober-up and your eyes clear, all that "consistent measurement" with the Thingy will be a figment of your imagination. If you are not "drinking" when you begin using the Thingy, you soon will be.

Is it true they include Alcoholics Anonymous membership in with the Thingy?

Ya know HC sometimes I wonder......You claim people can`t get a consistant lgt to ogive measurement with a Stoney Point to 0.001". yet anyone can accuratly measure to 0.0001" off a "usually oblong" case head with a mic.

quote:

Originally posted by Ol` Joe:
Ya know HC sometimes I wonder......You claim people can`t get a consistant lgt to ogive measurement with a Stoney Point to 0.001". yet anyone can accuratly measure to 0.0001" off a "usually oblong" case head with a mic.

I see your confusion. One is done with a Thingy supposedly secured to the "polished" blade of a 0.001" capable Caliper.

The other is done with a precision measuring instrument capable of 0.0001" accuracy - and with no dangling catywhampus Thingys in the way. Also, no drinks are needed to be able to repeate the precision accuracy results from the exact same spot.
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Rumor has it that 4x the number of Aspirin/Tylenol/Advil/Aleve/Darvoset are consumed in homes with "Things", than "Thingy Free" homes.