Sorting bullets for accuracy

[abinok]

im not sure if this topic has been covered yet, I tried running a search, but got either nothing or everything. If it has, and somebody can post the link, Ill let this thread die an early death.... On to the topic.


Ive been reading/thinking about the culling process used by many benchrest shooters. supposedly the best way to make the smk's shoot with the custom bullets is selective culling, and grouping the like bullets.
I have been shooting 220SMKs for a couple months now at 1350, and I have notticed a marked trend towards a 2 and 1 group, or 3 and 2 group, depending on 3 or 5 shots.
I just finished sorting a box and a half of these bullets. here is what I found.
lot#001830853
4 @.674
8 @.674
3 @.675
24 @.676
13 @.677
the other was a full box from
lot#001831067
1 @.673
10 @.674
10 @.675
46 @.676
32 @.677
1 @.678

In the next few days im going to find some time to sort the larger samples within a given length for weight as well, then shoot these to see if I can shrink those groups on down.
Any body out there sorting bullets by bearing surface or by any other method than weight?

 

[goodgrouper]

I had an earlier post on this very subject but I couldn't find it.
Yes, there is an ogive variance in custom bullets and it can make a big difference at long ranges. I noticed that bullets measuring .002" difference in ogive length hit about 2' 6" higher at 1785 yards out of my 6.5-.284! So now I measure every bullet(before and after seating) and put them into rows in my ammo box according to ogive length. The .002" diff didn't make too much difference at 1000 yards, but it was still noticeable on a calm day.

 

[abinok]

were you measuring from the base to ogive, or ogive/bearing surface juncture to the boattail/bearing surface juncture?

 

[goodgrouper]

Base to ogive on a Stoney-point bullet comparator. I have found this tool to be very accurate if you put consistent pressure on your calipers.

 

[abinok]

basically the same setup im using. Im using twin comparitors for bearing length measurement. Much faster than using my neco, and youre right, just as accurate if you use cosistant pressure.
maybe ill go back and do some measuring to see where the extra length is... compare the bearing surface inconsistancies vs the base to ogive length.
My rifle keeps "wanting" to shoot smaller groups at that range, I can usually get a few in 5"-8", but one always manages to open it to 14"-20". Very annoying. Then I have to stay up till 2am trying to figure out what im missing...
Ive gotta figure out how to weed that one stinking bullet out, that way I can get some sleep!

 

[Richard338]

I sorted some .338 300SMK by bearing surface. They were all one of two lengths, with one odd one a couple thou longer.
I tested the accuracy, but had also checked concentricity, neck-turned and a few other things for the first time.
I was very happy with the groups, but can't say how much was the bearing length sorting.
I also trimmed meplats.

 

[jb1000br]

FWIW--I also use the dual SP comparitors, but a local buddy that builds his own perfectly little precisie bullets is telling me i might be better off sorting by OAL.

might try both on paper and see what happens.

also FWIW, i have found my case of lapua 105 scenars to be EXTREMELY close in BS length--even better than customs i have measured.

and by extremely close i mean 200 bullets broke down into 4 BS lengths (.543-.546 IIRC) with only 3!! bullets outside of .544"-.545"

the other 197 were pretty evenly split between .544"BS and .545"BS

YMMV,
JB

 

[abinok]

I gave some thought to measuring oal, but to me, it seems like point variations would mask any other variations. When I can sort bearing length to .001, and oal can vary .030, it seems kinda pointless. maybe Ill have to go to the meplat uniformers like Tooley and others are making... or maybe if I sourted for oal, then bearing length, then base to ogive after sorting for weight.
I think that testing the variables one by one would be almost impossible at 1000 or more yds, maybe if I get a new barrel, a couple thousand bullets, a few pounds of powder, and about 6mos of stable air....and now my head hurts...

I keep wondering how much this sorting effects internal ballistics, and how much of it is external (bc variation).
Anybody tried to document ES reduction with sorted bullets?
So many choices...
I fear many hours at the reloading bench are ahead

 

[Varmint Hunter]

Addiction is a serious problem in this country. Have you ever considered going to the ammo doctor?
/ubbthreads/images/graemlins/shocked.gif /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/shocked.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

VH

 

[abinok]

Im in the 12 round program.... of did he say step....
you never know addiction untill you've sneaked a box of 210 bergers into the house /ubbthreads/images/graemlins/grin.gif

 

[Dave King]

I used to be bad about this stuff too... Now I just shoot the bullet and it doesn't hit exactly where I intended I say it was a bad bullet and discount that shot (remove it from the group) also knowing I'll never need to deal with that less-than-accurate bullet ever again. /ubbthreads/images/graemlins/smile.gif My groups have opened up a good deal but once I remove the "bad bullets" I'm usually down in the 0.0 to 0.25 MOA range... /ubbthreads/images/graemlins/smile.gif


Actually, as much as I hate to admit it, I'll need to start doing some sorting myself. I'm really interested in shooting at least one "Possible" at each range during this years' F-Class matches. Last year I shot factory Federal Gold Medal Match (GMM) and only managed to get a high of 17 of 20 'X's.

 

[abinok]

I may just have to do that, and forget the flyer.... maybe go to a 4 shot group, and drop the bad one if there is one.
Course if I do that, ive got a 2.75" group at 1350 /ubbthreads/images/graemlins/grin.gif
While im definately not considering shooting gane at this range, I do believe that practicing at 1350 makes shots at 800-1000 MUCH easier. Im just not willing to risk wounding game (or loosing a match) to that one bullet, hence the topic. I shoot prone from sandbags or bipod at these distances, and Im looking for an f class match around here to try.

 

[Dave King]

Now you got me doing it!!

Just came up from the basement where I was sorting my SMK 175s. I had two different lots of bullets, a single box of one lot# and two boxes of another lot#. I ended up with 4 lots of bullets (and a few culls I had thrown into the single opened 175 box.)

I measured from a point on the ogive to the base and it appears there was a .003 difference between the two types of bullets in each of the lot# boxes. I did manage to get a single group of about 120 bullets so I have enough for an upcoming match/clinic that required 100 rounds.

I plan to use these sorted bullets with some RWS brass and a super benchrest set of procedures to up my F-Class scores a bit... If it fails to work it's all your fault.

 

[Glock119]

pardon my ignorance, but what exactly is the, "F-Class" ? As i do not do any competitive shooting, I was just wondering.

Thanks,
Ben