Consistent base to ogive measurements

[inkballedtarget]

What are y'all using to measure your OAL and Base to ogive lengths?
I have a set of calipers, and when using the Hornady comparator inserts, it seems to be accurate but not very consistent. When measuring base to ogive, 75% of the base of the cartridge is hanging off the jaw of the caliper to get the cartridge straight and square.

I was curious if anybody was using a height gauge? This would essentially be the same process except give you a larger and more stable base to place the cartridge on.

Iam quite new to reloading, so I'm sure there is something else thay y'all are using.

It very well could be that the issue is not in the caliper, but in the Hornady comparators. Would something like this foster datum dial give more consistent readings?
http://www.forsterproducts.com/catalog.asp?prodid=755763&showprevnext=1

Thanks!

 

[jimcasey01]

Possibly you are over thinking this. It should be of no harm if the case head is not completely on the caliper jaw (part of the case hanging over the side of the jaws), as long as it is square within the calipers. This condition should not affect the reading.

 

[inkballedtarget]

Possibly you are over thinking this. It should be of no harm if the case head is not completely on the caliper jaw (part of the case hanging over the side of the jaws), as long as it is square within the calipers. This condition should not affect the reading.

Thank you for the reassurance. I was hoping that's all it was. Are most guys just running calipers?

Thanks,
Calvin

 

[jimcasey01]

Possibly you are over thinking this. It should be of no harm if the case head is not completely on the caliper jaw (part of the case hanging over the side of the jaws), as long as it is square within the calipers. This condition should not affect the reading.

Thank you for the reassurance. I was hoping that's all it was. Are most guys just running calipers?

Thanks,
Calvin

Calipers, yes, but use a very light pressure on the calipers. You can push hard enough to get almost any reading you "want" from calipers.

 

[inkballedtarget]

Possibly you are over thinking this. It should be of no harm if the case head is not completely on the caliper jaw (part of the case hanging over the side of the jaws), as long as it is square within the calipers. This condition should not affect the reading.

Thank you for the reassurance. I was hoping that's all it was. Are most guys just running calipers?

Thanks,
Calvin

Calipers, yes, but use a very light pressure on the calipers. You can push hard enough to get almost any reading you "want" from calipers.

Thanks!

 

[mikecr]

There is an adage if it isn't perfectly true, float it.
I use calipers but with a Sinclair 'nut'. Loosely handheld, and more consistent than caliper attachments. It's even more consistent for me than dial indicator measuring systems(ala BSC).

 

[ericbc7]

I have had very poor repeatability with any hand held comparator +calipers. "Floating" dies might help reduce run out but any play between comparitors, case and caliper = unreliable measurements. I was only able to get repeatable measurements with calipers by making jigs to hold cases and comparators in line. I now use the Inovative Technologies Digital Headspace Gauge and make a dummy round for each different bullet and rifle I load for seated to "jam" for reference. That gauge has reduced my reloading-stress level considerably.

I presume there are some loaders out there who can get repeatable (+-.001) measurements with hand held calipers but I'm not one of them.

 

[madmixerman]

Hornady has a base anvil for the calipers.

http://www.sinclairintl.com/reloading-equipment/measuring-tools/bullet-comparators/hornady-lock-n-load-anvil-case-prod41213.aspx

 

[mikecr]

I now use the Inovative Technologies Digital Headspace Gauge

I have one of these also. It's not designed for, or accurate for CBTO measure. It's designed only for comparative HS measure.

 

[jlow]

The Hornady comparator inserts are very accurate. I have used them with both a cheaper Chinese digital caliper and a Mito digital caliper (probably the most expansive) and it works perfect on either.

The reason you are not getting reproducible measurements could be because the base of the bullet/round is not sitting flat on the jaws of the caliper. The proper way to use it is to insert the nose into the comparator, gently close the caliper and then gently rock the bottom of the bullet/round so that it is sitting flat and perpendicular to the jaw of the caliper. All of this time you must not excert undue force on the caliper or the bullet will be forced into the comparator.

You should be able to get readings that are within 1 thousands. Now, having said so, you will find VLD bullets to be touchier since you are approaching their ojive at a sharper angle and it will be easier to jam the bullet into the comparator.

 

[mikecr]

you will find VLD bullets to be touchier since you are approaching their ojive at a sharper angle and it will be easier to jam the bullet into the comparator.

This is opposite of reality.
The sharper angle to bearing(from secant ogives) provides a better datum contact than tangent ogives, which are very near bearing diameter for a longer distances. This attribute of tangent ogives sets up for a more wedging datum, and it's why bullet seating plugs have to be much lower on bullet noses.

So while tangent ogives may be more forgiving for seated performance, they're not more forgiving in measurement.

 

[jlow]

Thanks mikecr - It’s funny because I seem to have slightly more problem with the VLDs, thus the comment. However, what you say do make sense to me. Wonder if anyone else has the same problem?

Don’t think the bullet is sticking since the same comparator works with my other tangent ogive bullets without much problem

 

[inkballedtarget]

I have had very poor repeatability with any hand held comparator +calipers. "Floating" dies might help reduce run out but any play between comparitors, case and caliper = unreliable measurements. I was only able to get repeatable measurements with calipers by making jigs to hold cases and comparators in line. I now use the Inovative Technologies Digital Headspace Gauge and make a dummy round for each different bullet and rifle I load for seated to "jam" for reference. That gauge has reduced my reloading-stress level considerably.

I presume there are some loaders out there who can get repeatable (+-.001) measurements with hand held calipers but I'm not one of them.

Thanks for this, it's nice to know I'm not the only one that struggles for repeatability. I will look into the innovative technologies headspace gauge.

 

[inkballedtarget]

Hornady has a base anvil for the calipers.

http://www.sinclairintl.com/reloading-equipment/measuring-tools/bullet-comparators/hornady-lock-n-load-anvil-case-prod41213.aspx

So you use this to give you a larger base. Have you had pretty good results with this, or is it only slightly better than the jaw of the caliper if any.

 

[tenring]

Having the case base sit consistently straight on the caliper blade requires a tight fitting base.
For that reason I like the Davidson base and nose pieces sold by Sinclair.
I have tried the Hornady and the hex nut, neither beats the Davidson unit.

 

[Joe Salt]

I use the Hornady base with the Sinclair nosepiece to measure OAL, and use the Innovative Technologies Headspace gauge. The reason is my hands are too big and I need all the room I can get to allow for error. Oh and the JB comparator to measure Bullet BS. It can also be used for Base to Ogive. If anyone cares.

Joe Salt

 

[mikecr]

Lotta ways to skin the cat. 'Best' may very well be whatever happens to work best for us individually.

 

[delv7915]

SELLING - Caliper Bases - $22.00 Shipped

Updated - 12.31.2024 - Current time from purchase to received - 3-4 days. Ensures consistent and repeatable measurements during the bullet seating process. See forum comments, reviews and feedback. PM me for additional information. 6061 Aluminum - Hard Anodized Black. Use in conjunction with...

forum.accurateshooter.com

These work amazing!

 

[WSnyder]

10yo thread and you're plugging your product

 

[TTE]

I have the SAC comparator inserts. They seem to be quite accurate.
One thing, when measuring OAL, make sure your bullet (tip) is not hitting the end of your comparator.