Bullet Comparator for bullet sorting stand - help please

[LoanHarvey]

I need a bullet comparator for a 25 Cal, specifically for the 131 ACE Blackjack bullet. I could not find one of these in 25 Cal, so I bought a .243 knowing I would have to somehow ream this out. What is the best way to do this. I would like the finished product to where the 131 Ace sets in there on the ogive. See pic....and thank you for your input.

 

[ppaul]

As long as you're going to sacrifice that .243 comparator I'd bore it out to .500, install a set screw and use one of the Sinclair bullet comparators that fit in the gauge made for calipers. Brownells has one listed for .257.

 

[Dusty Stevens]

Id run the chamber reamer in there to where the neck just touches the end. Youll have the exact representation of your chamber. This is how i make all my bullet comparators

 

[LoanHarvey]

Id run the chamber reamer in there to where the neck just touches the end. Youll have the exact representation of your chamber. This is how i make all my bullet comparators

Hey Dusty, that is a great idea. I have a .257 Wby Mag reamer, 25 SAUM and a 25x284 reamer setting here. I suppose they would all work, correct?
What would you charge me if I sent this small project to you and ship it back?

 

[Dusty Stevens]

Ill send you a pm

 

[JimSC]

if it is just being used as a comparator there is no need to ream anything out since you are simply comparing one bullet to the next and not looking for a exact measurement. As long as the hole on the comparator is smaller than the diameter of the bullet it will work for your purpose. I used a .22 insert to check my 6mm for several weeks before ordering a .243 insert, as long as I was comparing apples to apples it worked fine

 

[Dusty Stevens]

if it is just being used as a comparator there is no need to ream anything out since you are simply comparing one bullet to the next and not looking for a exact measurement. As long as the hole on the comparator is smaller than the diameter of the bullet it will work for your purpose. I used a .22 insert to check my 6mm for several weeks before ordering a .243 insert, as long as I was comparing apples to apples it worked fine

Bullets vary in shape ahead of and behind the ogive. You want to measure them to sort right where the bullet meets the leade otherwise they will still vary in their jump distance which is whats important

 

[JimSC]

Bullets vary in shape ahead of and behind the ogive. You want to measure them to sort right where the bullet meets the leade otherwise they will still vary in their jump distance which is whats important

that makes sense, thanks for the something new for today

 

[STS]

If the intent is to sort bullets for length within a particular lot, then it makes no difference if the bullet contacts the comparator at the leade or not. The only way it it would make a difference is if the bullets were pointed in different dies. The point up die makes the same shape on every bullet, so if you measure at a point forward of the leade or on the leade you will be accurate in sorting the bullets for length.
If the intent is to compare bullets from different dies (ie a different manufacturer or a different style of bullet) for the purpose of constant seating depth then you need a comparator that is an exact match of your chamber leade.

 

[Dusty Stevens]

If the intent is to sort bullets for length within a particular lot, then it makes no difference if the bullet contacts the comparator at the leade or not. The only way it it would make a difference is if the bullets were pointed in different dies. The point up die makes the same shape on every bullet, so if you measure at a point forward of the leade or on the leade you will be accurate in sorting the bullets for length.
If the intent is to compare bullets from different dies (ie a different manufacturer or a different style of bullet) for the purpose of constant seating depth then you need a comparator that is an exact match of your chamber leade.

You should measure some bullets with different size comparators then. See if all the measurements are the same on all bullets (they wont be) and like you said- pointed in different dies (they are except the few hand made customs). Lube and lead flow and jacket composition makes them different. Grab some bergers or sierras, sort them to the same measurement in a group then measure 2 more spots. They should be all the same if youre right

 

[STS]

If you have bullets that are pointed in different dies in the same box you have bigger problems than sorting for length will solve. I've made custom bullets for 45 years and I've never figured out a way to make a different shape bullet in one pointing die. If the shape is the same then it makes no difference where you measure along that shape if you are wanting to sort for length as the OP is wanting to do. You can measure bullets out of the same die with a 22 and a 6mm comparator and if the bullet is .002 difference in length with one comparator it will be .002 with the other because the ogive is the same shape. Think of it in terms of thousandths taper per inch like a Morse taper. Same shape = same measurement.

 

[JimSC]

Grab some bergers or sierras, sort them to the same measurement in a group then measure 2 more spots. They should be all the same if youre right

I went over to the bench just to see. Used 6mm Berger 105 Hybrids and .20, .22. and .24 Hornady comparators. Measured with a Starrett 120A calling anything between the 2 marks as .0005. I only did 5 bullets but that was more than enough to show me you are correct. The smaller the hole showed the least amount of variance, the .240 insert had the largest variance. Bullets sorted with the .240 would be ones most likely to encounter the throat at the same spot if the bullet is perfectly centered on the bore. Not sure how much difference there would be on paper but for the perfectionists it makes sense to use the correct insert

 

[Dusty Stevens]

I went over to the bench just to see. Used 6mm Berger 105 Hybrids and .20, .22. and .24 Hornady comparators. Measured with a Starrett 120A calling anything between the 2 marks as .0005. I only did 5 bullets but that was more than enough to show me you are correct. The smaller the hole showed the least amount of variance, the .240 insert had the largest variance. Bullets sorted with the .240 would be ones most likely to encounter the throat at the same spot if the bullet is perfectly centered on the bore. Not sure how much difference there would be on paper but for the perfectionists it makes sense to use the correct insert

It doesnt make much difference, none to most, but if we’re going to sort bullets it makes sense to sort them where it matters- and the artificial ogive barrel stub gives you a real measurement. Its just an eye opener for the sorting types, and if youre going to sort i think you should sort where it matters (the whole area of contact)

 

[dcali]

Id run the chamber reamer in there to where the neck just touches the end. Youll have the exact representation of your chamber. This is how i make all my bullet comparators

Maybe I’m doing it wrong, but I have gotten very poor results doing this. The variability was in the neighborhood or .010”, when normal inserts were closer to .001” (all on the same bullet). Maybe it has to do with the type of bullet (mine have very gradual ogives in that area). I’ve grown suspicious of BTO measurements these days in general. It’s like measuring diameter to the tenth - harder than it looks.

 

[Dusty Stevens]

Maybe I’m doing it wrong, but I have gotten very poor results doing this. The variability was in the neighborhood or .010”, when normal inserts were closer to .001” (all on the same bullet). Maybe it has to do with the type of bullet (mine have very gradual ogives in that area). I’ve grown suspicious of BTO measurements these days in general. It’s like measuring diameter to the tenth - harder than it looks.

The reamer used makes a big difference. If the bullet has a rounded contact on it then it is hard to measure

 

[billshehane]

Save your .243 set and send me a bullet and I will send you a text picture of your bullet in our .25 cal. bearing surface comparator bushing set.