Bob Green Comparator/140 gn Hybrid Sort Results FWIW

[/VH]

Earlier this week, I spent a couple evenings sorting ~ 1k Berger 6.5 mm, 140 gn Hybrid bullets, lot # 7952, with my Bob Green comparator. Yes I know, I need to get a life. Anyway, after sorting, I actually counted the bullets and I thought the results might possibly be of some benefit or interest to someone else on here that also might be in need of a life.

If it turns out that this post is of no more use than obama, at least it won't take near as long to get rid of.

So, I sorted 502 bullets, Sunday evening and 502 bullets, Monday evening, as each of the two boxes contained 2 extras. I started by rinsing them in lacquer thinner and giving them a few minutes to dry cuz clean matters in this operation.


If I remember correctly, the Bob Green comparator instructions say to sort into groups that measure within .001" of each other but with what I have for a life, I decided to cut that in half and sort to .0005". Now, please understand that this was not extremely scientific. I may have screwed up a couple and the bullets that measured borderline, may have fallen in either group, kinda depending on how I felt at the moment.

For those not familiar with the Bob Green comparator, the idea is that it comparatively measures the longitudinal difference between bullets of the distance from roughly, where the seater stem makes contact on the ogive to roughly, close to the where the ogive and bearing surface intersect. Knowing that statement might be difficult to follow, even if I did get it right; basically by sorting with it, and if your seating force is consistent...and there are no other kinks thrown in; when you seat your bullets, all your loaded rounds will measure the same from the case head to the bullet ogive.

So, here are the results:
Out of the 1004 bullets, I grouped them into 6 main sets by .0005" increments which covered a total range of .003" and included 983 bullets, if I cyphered my take aways correctly.

There were a few outliers; 16 ea. measured shorter than my chosen range and/or acted goofy in the comparator. 4 ea. measured longer and/or acted goofy. 1 bullet, I dropped on a ceramic tile floor and I believe I damaged it in doing so. This makes a total of 21 outliers. The rest went like this:

4 ea @ .1570" - .1575"
57 ea @ .1575" - .1580"
152 ea @ .1580" - .1585"
347 ea @ .1585" - .1590"
356 ea @ .1590" - .1595"
67 ea @ .1595" - .1600"

I hope this is of some use or interest to someone. If not, we'll impeach the thread. Also seems to me Berger has been putting out some pretty consistent bullets, especially considering how many they run and the results on target are better than my shooting ability. Scenars have sorted very well for me, also. For some of the other brands, I'll have to buy some more green chili dip so I'll have enough plastic bowls to sort into.

 

[MrBottleneck]

Interesting findings.

You must really been bored.

 

[bsumoba]

Looks like a standard distribution curve.

what would be more interesting is if the outliers shot any different.

I would take those and try to objectively shoot them in a known good barrel with a known good load.

 

[BenPerfected]

Looks like a standard distribution curve.

what would be more interesting is if the outliers shot any different.

I would take those and try to objectively shoot them in a known good barrel with a known good load.

Add to the list shooting in a Pappas 1pc rest in very calm conditions.

 

[Jet]

Thanks for posting Brian

I use the same tool and sort in .001 increments and my results with Hybrids are similar to yours. Bearing surface measurements are the 1st sort I use then use the Bob Green tool. With it I look more for the bullets that will screw up a group. In my experience, every box of 500 has at least a couple.

If you want to get part of your life back, start shooting Vapor Trail bullets. They are the most consistent bullets I've ever sorted.

Good Shooting.

Rich

 

[Joe R]

Earlier this week, I spent a couple evenings sorting ~ 1k Berger 6.5 mm, 140 gn Hybrid bullets, lot # 7952, with my Bob Green comparator. Yes I know, I need to get a life. Anyway, after sorting, I actually counted the bullets and I thought the results might possibly be of some benefit or interest to someone else on here that also might be in need of a life.

If it turns out that this post is of no more use than obama, at least it won't take near as long to get rid of.

So, I sorted 502 bullets, Sunday evening and 502 bullets, Monday evening, as each of the two boxes contained 2 extras. I started by rinsing them in lacquer thinner and giving them a few minutes to dry cuz clean matters in this operation.


If I remember correctly, the Bob Green comparator instructions say to sort into groups that measure within .001" of each other but with what I have for a life, I decided to cut that in half and sort to .0005". Now, please understand that this was not extremely scientific. I may have screwed up a couple and the bullets that measured borderline, may have fallen in either group, kinda depending on how I felt at the moment.

For those not familiar with the Bob Green comparator, the idea is that it comparatively measures the longitudinal difference between bullets of the distance from roughly, where the seater stem makes contact on the ogive to roughly, close to the where the ogive and bearing surface intersect. Knowing that statement might be difficult to follow, even if I did get it right; basically by sorting with it, and if your seating force is consistent...and there are no other kinks thrown in; when you seat your bullets, all your loaded rounds will measure the same from the case head to the bullet ogive.

So, here are the results:
Out of the 1004 bullets, I grouped them into 6 main sets by .0005" increments which covered a total range of .003" and included 983 bullets, if I cyphered my take aways correctly.

There were a few outliers; 16 ea. measured shorter than my chosen range and/or acted goofy in the comparator. 4 ea. measured longer and/or acted goofy. 1 bullet, I dropped on a ceramic tile floor and I believe I damaged it in doing so. This makes a total of 21 outliers. The rest went like this:

4 ea @ .1570" - .1575"
57 ea @ .1575" - .1580"
152 ea @ .1580" - .1585"
347 ea @ .1585" - .1590"
356 ea @ .1590" - .1595"
67 ea @ .1595" - .1600"

I hope this is of some use or interest to someone. If not, we'll impeach the thread. Also seems to me Berger has been putting out some pretty consistent bullets, especially considering how many they run and the results on target are better than my shooting ability. Scenars have sorted very well for me, also. For some of the other brands, I'll have to buy some more green chili dip so I'll have enough plastic bowls to sort into.

I must not have a life either because I also have been sorting bullets, but in .001 increments. IMO going to .0005 is really unnecessary because of the simple fact that bullets are not perfectly round, nor are the comparators, so... when measuring the bullets if you turn them 90 and/or 180 degrees you will get a different numbers.

It is also my experience/observation that on target I couldn't see the difference between bullets that were +/- 0.001. I seriously doubt you will see a difference in POI with .0005 differences.

Now if you really want to drive yourself crazy, use your outside micrometer that can measure to 0.00005 and start measuring a bullet at different degrees of its bearing surface. You will get different numbers on the same bullet, not to mention what happens from one bullet to another, I'm pretty certain that there has to be differences in circumference. In my mind circumference differences are far more important than BBTO, yet no one that I know measures that. I'm sure there is tool that does that, but I have no idea what it is. I'm afraid what would happen if I started to investigate that. I think my wife/children may have me committed into a psychiatric hospital.

And then there is the wind....

Joe

 

[joshb]

In quiet corners of the country, a few dedicated individuals carry on with diligence and obsessive determination!

 

[mikecr]

What of the meplat diameters?
You won't shoot ogive radius variance in itself, but rather the affects of it.

 

[/VH]

I must not have a life either because I also have been sorting bullets, but in .001 increments. IMO going to .0005 is really unnecessary because of the simple fact that bullets are not perfectly round, nor are the comparators, so... when measuring the bullets if you turn them 90 and/or 180 degrees you will get a different numbers.

It is also my experience/observation that on target I couldn't see the difference between bullets that were +/- 0.001. I seriously doubt you will see a difference in POI with .0005 differences.

Now if you really want to drive yourself crazy, use your outside micrometer that can measure to 0.00005 and start measuring a bullet at different degrees of its bearing surface. You will get different numbers on the same bullet, not to mention what happens from one bullet to another, I'm pretty certain that there has to be differences in circumference. In my mind circumference differences are far more important than BBTO, yet no one that I know measures that. I'm sure there is tool that does that, but I have no idea what it is. I'm afraid what would happen if I started to investigate that. I think my wife/children may have me committed into a psychiatric hospital.

And then there is the wind....

Joe

Lord, please don't let me get as bad as Joe, amen!

 

[/VH]

Thanks for posting Brian

I use the same tool and sort in .001 increments and my results with Hybrids are similar to yours. Bearing surface measurements are the 1st sort I use then use the Bob Green tool. With it I look more for the bullets that will screw up a group. In my experience, every box of 500 has at least a couple.

If you want to get part of your life back, start shooting Vapor Trail bullets. They are the most consistent bullets I've ever sorted.

Good Shooting.

Rich

Thanks for the tip Rich. Who sells them?

I actually did a little deer hunting today!

 

[/VH]

What of the meplat diameters?
You won't shoot ogive radius variance in itself, but rather the affects of it.

Well, I was planning to trim and point them but I'm listening, Coach!

 

[Jet]

Thanks for the tip Rich. Who sells them?

I actually did a little deer hunting today!

The one I use is made by Mark King. Don't think he makes them anymore.

 

[/VH]

The one I use is made by Mark King. Don't think he makes them anymore.

Sorry, I meant Vapor Trails.

 

[Jet]

Tom Jacobs http://vaportrailbullets.com/

He has some 6.5s coming out soon.

 

[/VH]

Thank you.

 

[/VH]

Looks like a standard distribution curve.

what would be more interesting is if the outliers shot any different.

I would take those and try to objectively shoot them in a known good barrel with a known good load.

Bryan ,
Shall I send them your way, with a handful of 'inliers'? Me shooting them might not prove much.

 

[bsumoba]

Bryan ,
Shall I send them your way, with a handful of 'inliers'? Me shooting them might not prove much.

No need. I've done similar tests and I cannot tell you objectively one way or the other if it will consistently group worse. For me, I just don't shoot them for record shots from a consistency standpoint.

 

[mikecr]

Well, I was planning to trim and point them but I'm listening, Coach!

Ogive radius variance affects any device taking datum off ogives. Thats seating/measuring CBTO and the best in meplat work. Both of these make a difference to shooting results.

CBTO is taken care of by simply making every round made the same. Meplat work is not as easy.
Meplat tools trim/close to lengths instead of desired diameters. Nose length or OAL.
OAl is too broad to achieve same diameter meplats. You can trim/close to same diameters provided nose length datums are consistent.
That's where you need to match ogive radius beforehand. With this you can more closely match BC, which shows at distance, because meplats play a large roll in BC. In fact, larger than other common bullet variances.

To compare ogive radius only and think you'll see it with shooting is a misconception of the potential in it.

 

[DocBII]

/vh,

You may wish to set your trimmer up so it only removes 0.005 or so at a time. Take the ones which didn't get trimmed completely and take off another 0.005, repeat until done. I've found Bergers to vary by 0.025 in overall length after trimming, which I kept in +/- 0.0025 groups. The length makes a difference if you point them after trimming. Then again, one of my shooting buddies just points the snot out of the bullets and doesn't pay any attention to the length, and he does well.

HTH,
DocB

 

[/VH]

Thanks DocB, my memory is not real good but it seems like with this lot of bullets I have generally been trimming from about .003" to about .012" and getting full cleanup on all but one of the 500 or so that I've already trimmed.