Tool for measuring cartridge length from the ogive

[hoz53]

My 2¢ One is just looking for a reference point so as long as the tool is used consistently, they all will work. The Hornady unit is an easy one to make custom inserts for.

i think youre right about the consistency. ive got the sinclair-- it looks like the davidson holding the case base like it does would help with consistency. may have to get one and try it although i sure have alot of inserts for the sinclair and i have a hornady i havent used.

 

[JimSC]

I use the Hornady, it works fine and has the best price. If you have a good drill set, drill press and a piece of aluminum or steel you could easily make your own. This is just a set of holes in metal when it comes right down to it

 

[TerryH]

am I missing something ? what does the Davidson tool do that the Hornady tool doesn't ?

I have both. These are my observations. First, the hole in the Davidson comparator is tapered. .301 a the mouth tapering to .285. The Hornady has a straight .298 hole. This makes the fit more precise in the Davidson. For example, on the Berger 200.20x's when I insert the bullet in the Hornady it does not actually measure to the ogive but further up on the taper so the bullet easily moves around side to side. When the bullet is inserted in the Davidson the connection is solid and there is zero movement. The base that Davidson offers was the game changer for me. It stabilizes the cartridge head and makes getting an accurate measurement much easier. It has steps machined on the inside which makes sorting bullets much simpler as the base of the boat tail has a spot to seat that is square to the comparator. Not necessarily more precise than just using the blade on the calipers but it makes getting a precise measurement easier. The precision and ease of use makes the Davidson worth the money in my opinion.

 

[marchboom]

I have the following:

Hornady comparator: Use it quite a bit. I like it but if I didn't have one I would get the Sinclair as it is made out of stainless steel. Very fast to use.

Davidson: I use this for measuring base-to-ogive only. Works great. Again, fast to use.

Precision Mic: Really like this but takes a little more time to use. Very accurate. Can be used to measure base-to-ogive and base-to-shoulder and has an insert to measure actual chamber dimensions for setting up seating depth. Only downfall is the price and it's only for one caliber.

Bottom line: If I didn't have any comparator tool I would get the Sinclair.

 

[T-shooter]

I like the Hornady but have never used anything else. Lower cost was important to me. Using what they call the anvil base helps instead of just using the jaws of the caliper. Also wiggle the case base around to get it to sit as flat as possible. I assemble all the pieces on the caliper and compress until they align together evenly before tightening the set screws. The measurements you get are fine for comparison purposes once you've established a baseline. The bullet inserts I have are both .010" smaller than the O.D. of the bullets. Also, you cannot directly compare with a the same tools that someone else has. I found the readings I got on a .223 set were a little different than a friends set. That doesn't matter since you should only use these to compare your own components.

 

[Grimstod]

How hard are you squeezing those calipers down that aluminum deforms?

Hardly pressing at all. The problem with aluminum ones is the they wear and you get different readings over time. Also cardinal rule about indicating is that your indicating tools should be made of metal that expands in a similar rate. Aluminum expands almost twice as much as stainless does.

 

[Richard Coody]

My 2¢ One is just looking for a reference point so as long as the tool is used consistently, they all will work. The Hornady unit is an easy one to make custom inserts for.

now he has got it. no matter how precise the tool that base to ogive measurement is just a reference. differences in bullet ogives and actual seating depths of bullets are going to give you more variation than the different tools. When you take this to the next step and start measuring CBTO at that elusive "touch" the little variation in the different tools goes right out the window.

as long as the tool's measurements are repeatable within reason that is all you need. just remember your tools measurements and another shooters measurements are not comparable. Each different bullet you use will have to be measured and even the same bullet from a different lot number should be checked for ultimate accuracy.

 

[K22]

Frankford Arsenal tool - available at Midway. Cheap, easy to use. This will give you a practical measurement. Just keep in mind that depending of the bullet and brand, ogive can vary from bullet to bullet in a box and lot to lot.












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