Bullet Comparator

[6BRinNZ]

Hi,

I thought I would have a look at sorting bullets for base to ogive to see what results it might have on my groups for me so...

what Bullet comparator do you recommend?

When you do sort, what tolerance is acceptable i.e. .001" - .002" variance is ok?

Do you just cull bullets outside of tolerance?

I know some brands are not worth sorting....

Thanks

Wayne

 

[Joe O]

I use a Sinclair,that has a body,and caliber insert that attaches to a caliper.Hornady has a similar type,and Sinclair has other bullet sorting tools.The quest for more accuracy will take you further than most of us want to go,but it's compelling.I went through a partial box of Sie 95 gr 6mm Match bullets and found a .009 spread,between longest and shortest.I found 10 exactly the same and loaded them is prepared fireformed WW 243 AI cases.Five were OAL 2.744 and five were 2.758,all else the same.The shorter seated bullets shot a 3/4" group,after a one shot fowler.The second group (Longest OAL) came in a ragged hole, .226.I did not weigh the cases or the bullets,and neck tention may not have been exact,but close.No crono on these,but previous loads were in the 3200fps range (28" Hart barrel w/VAIS brake 1:9 twist).

 

[Rust]

The most accurate way to do it is to get a comparator insert of less diameter than the bore of the rifle you plan on shooting the bullets in and then have to insert drilled/reamed to the exact diameter of the barrels land diameter.

Some folks save and use the stub of the barrel they are using if a little has been cut from the muzzle end when chambering and mounting the barrel.

 

[bozo699]

Wayne,
I have been playing with bullet lenght also.Up untill the last week or so I was using two sinclair blade caliper type back to back,it worked better than just one comparator on caliper but still not getting the results I was looking for.Talked to a machinist friend of mine and he built a insert to fit the sinclair body that works awsome. I wished I knew how to post a picture on here,no more bullet sticking no more multiple different measurments on same bullet this thing works. Look on line @ the sinclair insert, instead of a straight cut sharp hole for your ogive to get stuck in it has a 45 deg cut on the face then down maybe 1/2" a 60 deg bevel the bullet fits in it perfectly no wobbling around no getting stuck same reading everytime.
Wayne.

 

[lurcher]

The tubbs comparator looks nice http://www.davidtubb.com/tcom_images/reloading/bsc_one.html
Sinclair sell something similar but the clamp stand is not high enough to be able to use it to measure loaded bullet OAL a nice extra feature of th tubs, but it is cheaper than the tubbs. you can alos use the larry willis headspace tool for base to ogive measurements www.larrywillis.com see http://www.larrywillis.com/bullet-shape.html

You can also use two hornady or sinclair ogive inserts and comparator bodies and a set of dial calipers. Interestingly on the tubbs web page they say sort bullets into lots with less than 0.003 variation in bearing length. I have read that you can do this with the comparator caliper set up.

If you buy a tubbs and by chance you live in dunners I will have to borrow it ;D

 

[hmcsr]

Here's one you might want to look at too.
http://redding-reloading.com/online-catalog/37-instant-indicator-headspace-and-bullet-comparator

 

[6BRinNZ]

Thanks guys,

a bit to chew over here.

Lurcher - I'm not in dunners but hey I'll loan ya a comparator for some good varminting farms

 

[lurcher]

No worries mate the rabbits are so thick in parts down here at the moment the regional council is breaking out the poison and getting tough on farmers to sort out infestations.

I am going to try the two comparator method for interest sake

see also http://www.6mmbr.com/medlerTUBBBSC.html
https://accurateshooter.wordpress.com/2009/11/14/sinclair-bullet-sorting-assembly-with-dial-caliper/

 

[DennisH]

I use the Hornady, Interesting, last night I was loading some SMK's and 140 JLK's, I started with the smk's and interesting they variend a few thousanths! I was loading 6.5 123 smk's and some 190's for my 308. I was surprised!

The I started loading some 140 JLK's for my 6.5x47L, They were almost all perfect and a few might have been off by .0005.5 , yes 1/2 of a thousanths! I was mearsuring 2.222 and some hit 2.222 1/2, hope I am wording the correctly, still on my first cup of coffee! I going to see how the JLK's shoot, heard many good things about them, might go strickly JLK! Just a short note, Bergers are pretty consistant with my Hornady guage.

 

[6BRinNZ]

Thanks Dennis,

did you notice much variation in group size with the smks varying so much? Something I am trying to get a handle on is reward for the effort i.e. would a 1" group shrink to 3/4" but a rifle shooting in the high .3s would only shoot in the low .3s.... and if people cull bullets.

 

[lmorrison17]

Here is the best thought out tool I have yet to see.

http://greensrifles.com/New_Products.html

 

[mikecr]

+1 Bob Greens Ogive Comparator.
The waters are only muddied by including bearing and base variances into comparison. What really affects accuracy is seated ogive contact-to-lands distance. This is so plain to see and test, it ain't funny(just vary seating depth).

Bob's tool isolates 'ogive radius variance' specifically.
This is often mistaken as bearing surface variance, and can also affect nose trim length with meplat trimmers.
Truth be told, most other bullet comparators(I've had most) are pure worthless.

We have a long ways to go here...

 

[4xforfun]

Are you shooting BT's or flat base bullets. Base to ojive is fine for flat base bullets, but not for BT's. I use the Shehane comparotor. It measures either base to ojive or Ojive to ojive on BT's ....bearing serfice length....very important!!!

 

[mikecr]

How is bearing surface length important?
How do you know that you're measuring bearing variance at all -without first qualifying ogive radius(your datum)?

Seriously, alot of what we're doing with these comparators is meaningless. Multi-variances combining to mean what exactly?
If a bullet varies from 'standard' by .002BTL, .002BSL, .002NL, .010MD, and -1.2deg ogive radius, what do we see?
We could see nothing, or any combination of it all, and we don't know what the affect of it all means really.
We don't know the affects on BC, MV, distance to lands, etc..

The only way to cull here with any hope of actual gain, is through individual parameter validations. And short of using a laser mic & software, some parameters have to be qualified before any measurements can actually be taken.

 

[6BRinNZ]

This from the forum boss has convinced me to check it out further

"My 6BR can shoot almost any good bullet in mid-threes or less in good conditions at 100 yards. With the 75gr Vmax I was getting 6s and 7s. I then switched to Berger 80s, and the gun shot in the high ones. Puzzled, I started measuring the VMaxs (both 75s and the 87s which also shot poorly). I saw variations in bearing surface up to 0.025 and variations in bullet diameter up to .0006 (six ten thousanths). That was the answer to that story."

I have gone with the sinclair tool.

 

[DngBat7]

Are you shooting BT's or flat base bullets. Base to ojive is fine for flat base bullets, but not for BT's. I use the Shehane comparotor. It measures either base to ojive or Ojive to ojive on BT's ....bearing serfice length....very important!!!

 

[dcali]

I use the hornady tool mostly. It's fine. Don't overthink it.

 

[CNC-Dude]

Brian Litz has a couple of videos where he gives his thoughts on this as well as case prep and a few other processes he has extensively tested in his Applied Ballistics lab.