Sinclair bullet comparator question

[queen_stick]

Ok guys, here's another question about precision measurement....

I recently purchased a bullet comparator to sort by bearing surface length. The first thing I noticed is that it's EASY to change the depth of bullet in the comparator body. What I mean, is that you can set the bullet in the comparator lightly and take a measurement, then lift the indicator pin and set back down on the base of the bullet, and it pushes the bullet into the comparator a little further. It's basically creating a 'jammed' fit. The difference between the first measurement, with the bullet just set into the comparator, and the second measurement, with the bullet slightly jammed into the comparator, is about .001." That's enough to make the process of sorting useless, and a waste of time. I've found that if I intentionally jam the bullet into the comparator prior to measurement it's much more consistent, but how do I know the pressure I'm using to 'jam' the bullet is consistent?

Anyone have the same experience, or more importantly, know how I can get consistent measurement?

 

[jo191145]

JMO
You get bullets within .001" + or - and no sorting is necessary.

 

[queen_stick]

jo191145 - I agree with that, but I'm getting + or - .001" on the same bullet, depending on the 'jam' into the comparator. If I'm not measuring consistently, then I don't feel the measurements are valid/true.

Walt

 

[jo191145]

Understood.
I see the same inconsistencys using the Hornady comparators with a caliper. I've learned to live with it and accept it. If I start seeing deviations greater than .002" I get concerned. When I see deviations .005"+ I stop buying those bullets
MAYBE (thats a big maybe)......... putting a slight chamfer on the comparator would help.
My first step would be calling Sinclair.

 

[queen_stick]

Good idea! I didn't even think of that. Maybe I'll give them a call tomorrow.

Thanks,

Walt

 

[queen_stick]

just wanted to add an update, which resolves the issue of inconsistent measurements.

Never did get around to calling Sinclair, but they gave me the answer in this article:
http://blog.sinclairintl.com/2010/02/19/bullet-prep/

The article explains that you need 'practice' in feeling the jam into the comparator in order to get good results. They give a step-by-step procedure that trains you how to take the measurement consistently!

Walt