consistent measurement with Hornaday case length comparator.

[FEENIX]

Let me preface this by saying I am new to this tool. When measuring cases I cannot get a consistent measurement. Spin the case inside the comparator and you get measurements that vary by .003 or more. This is brand new Lapua brass and brand new Peterson brass. I bought this to check my shoulder bump but with these results its pretty much useless. Any ideas what I'm doing wrong?

As others noted, the inconsistencies are due to the virgin brass. Measure when it is fire-formed from your rifle's chamber.

 

[ntsqd]

If you use a fire formed case, drill and tap the back end, you will be in a different world when it comes to getting uniform results with the Hornady. Hornady was slick when they made the drill size and tap a bastard size.

What thread did they use?

It also should be noted that using precision calipers consistently requires good technique all by themselves. The unwary can vary the measurement of a hard steel block by much more than the OP's variance. Then add-in the technique(s) required by what is actually being measured. That thumb-wheel is not your friend!

 

[VinceMule]

I have Starrett, Brown and Sharp, and Mitutoyo calipers, but always reach for a micrometer when I need precision numbers.

I will see if I have any extra taps on hand for the Hornady.

 

[bluedog69]

I think there are two different conversations going on in this thread.

1) Shoulder bump and how to measure it with the case comparator.(Hornady)

2) How to find the lands with a Hornady tool.

So if you are new to this don't let it confuse you.

 

[JAYgs8163]

^^. Good advice here. Using it on brand new brass is pretty useless with the exception of getting some starting points for your loads. Fire form your brass to your chamber and then go to work using the tool.

 

[ntsqd]

What thread did they use?
....

Found the answer; 5/16-36, which is a Special thread pitch.

https://www.mscdirect.com/product/details/04841367 ~$10+ shipping

https://www.amazon.com/gp/product/B00GU7OV5C/ ~$20

 

[Longtine88]

No batteries required. 1.5581"…?
View attachment 551674

I see 3.1581" - 2.00" = 1.1581" correct?

And I'll add that calipers are made for really only measuring to .001". There's too much flex in the design to allow for any more accuracy. the 1/10,000 place is pretty much useless.

 

[Longtine88]

I think there are two different conversations going on in this thread.

1) Shoulder bump and how to measure it with the case comparator.(Hornady)

2) How to find the lands with a Hornady tool.

So if you are new to this don't let it confuse you.

glad you pointed that out.

 

[Citified]

I bought the tool which has the tap, drill bit and a case holder. I sacrifice a once fired case in each caliber to get good measurements.

 

[Toad67]

If your not using the anvil, it's worth purchasing to help the case sit flat and level. Another thing to notice, is the slot on the comparator isn't cut in the middle. When attaching it to your caliper, make sure the slot on the comparitor lines up with the other jaw on your caliper. If they'e not aligned, you will cant the case a bit, and possible get irregular readings, this is why the base anvil helps out.

Hornady Lock-N-Load Bullet Comparator Anvil Base Kit

The Hornady Lock-N-Load Bullet Comparator Anvil Base Kit is perfect for the reloader looking to take accurate measurements of reloaded ammunition. When...

www.midwayusa.com

 

[huntinghuasna]

I see 3.1581" - 2.00" = 1.1581" correct?

And I'll add that calipers are made for really only measuring to .001". There's too much flex in the design to allow for any more accuracy. the 1/10,000 place is pretty much useless.

Not all calipers are created equal… I'd trust 1/4 to 1/2 thou with these steel Starretts. Wouldn't trust junk steel or plastic for sure. I'm not relying on 1/10,000 accuracy for this application. There are tools purpose built for that amount of accuracy. Also, the person holding the tool will cause different readings depending on their feel.

 

[cdherman]

I bought the tool which has the tap, drill bit and a case holder. I sacrifice a once fired case in each caliber to get good measurements.

I have not went this far, but considered it. I will also add -- some guns and loads do not fully blow out a case with the first firing. I would try and use a 2x or 3x fired case.

 

[Citified]

Good point.

 

[Coyote Shadow Tracker]

Found the answer; 5/16-36, which is a Special thread pitch.

https://www.mscdirect.com/product/details/04841367 ~$10+ shipping

https://www.amazon.com/gp/product/B00GU7OV5C/ ~$20

If you are using the Hornady OAL for Modified Cases - We have Drilled and Tapped hundreds of cases for members off our lathe. If you are going to DYI make sure you have a good drill press to drill and tap. If you tap by hand make sure you have a good vice to hold the case do it Straight.

If you are looking for Shoulder Bump we suggest using the Redding Instant Indicator Tool.