sorting by ogive length -how close is close enough

[juniorARshooter]

Sir
I am trying to tighten up my groups at 1000 yards (F-Class) and am sorting my bullets by base to ogive length. I am using Sierra 175 and am finding a max variation of +- 0.003 inches

My question for you guys who shoot long range and sort by ogive length - how close in length do you sort your bullets? Should I shoot strings of shots where the bullets are all 0.000 difference or is +- .001 OK? Remember F-Class X ring is 5 inches at 1000 yd

Would appreciate ANY input from guy who shoot long range targets

 

[zenbiker]

Re: sorting by ogive length -how close is close enough

Sort your bullets into groups of the same ogive length, then load them and shoot them in those batches. You probably already know that the ogive differences you're seeing are the result of different production lines dumping finished bullets in a common bin; wear of the pointing dies in each line accounts for the different ogive lenths. You also may want to test batches of ammo loaded with each different length to see if you can discern any difference, which is likely not going to show up until you start getting beyond 600 yards.

Probably just as important is checking each batch for weight variances and subgrouping them by .1 grain differences.

Beyond that, I don't have the patience.

 

[scaxeman]

Re: sorting by ogive length -how close is close enough

The Berger's I run have a similar base to ogive measurement spread. I typically toss them in 3 separate boxes based on where they fall. I use all of the projectiles, but load them one box at a time, and fire them in sequence. Therefore from round to round, the spread is effectively 0.000

As with 1Z above, I also sort them by bullet weight.

Hope this helps,

Darrell

 

[juniorARshooter]

Re: sorting by ogive length -how close is close enough

Thanks guys great input!

FYI Pretty consistent input from you guys as well as the current F-T/R national champ and a member of the Army all reserve team and US National Palma Team.

THANKS AGAIN!

 

[DAVETOOLEY]

Re: sorting by ogive length -how close is close enough

For what it's worth. I very familar with several, meaning more than two, bullet manufactures. I know of no one that mixes lots of bullets. Take Sierra for example. They may have added another bullet by now but several years ago there was only one bullet they made that was run on more than one press at the same time. That was the 30 cal. 168gr. HPBT. Bullet dies last a long time and are very expensive. Why would a company want to invest in more than one set until they were getting near the end of the life cycle of the tooling. That life cycle can be 3-5 million bullets.
Small variations in ogive to base length happen for several reasons. Unless you've made bullets and have seen a bullet press running it's hard to explain all the factors such as jacket lube or how the dies are set up and held in the press that effect the bullet during it's manufacture. Years ago we did get mixed lots that's not the case anymore. I've measured the BC's of bullets that had a ogive to base variation of .030". They came out of the same box. For all practical purpose they had the same BC. Sort to the tolerences that give you confidence. A range of .005" will not show up on the target. What you'll probably find is that your culls used for fouling shots and coarse sighters will shoot to same place.
Far more important is the effect the meplat has on the bullet. Irregular meplats cause variations in inflight bullet yaw resulting in variations in BC.

 

[strictlyRUM]

Re: sorting by ogive length -how close is close en

Well said Dave. I have run a few bullets in my time and never mixed lots. Even shot a couple thousand seconds which typically are from different lots. If you uniform meplats and weight sort too .3 grn groups usually you won't ever see the difference.

Jason

 

[zenbiker]

Re: sorting by ogive length -how close is close enough

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body">For what it's worth. I very familar with several, meaning more than two, bullet manufactures. I know of no one that mixes lots of bullets. Take Sierra for example. They may have added another bullet by now but several years ago there was only one bullet they made that was run on more than one press at the same time. That was the 30 cal. 168gr. HPBT. Bullet dies last a long time and are very expensive. Why would a company want to invest in more than one set until they were getting near the end of the life cycle of the tooling. That life cycle can be 3-5 million bullets.
Small variations in ogive to base length happen for several reasons. Unless you've made bullets and have seen a bullet press running it's hard to explain all the factors such as jacket lube or how the dies are set up and held in the press that effect the bullet during it's manufacture. Years ago we did get mixed lots that's not the case anymore. I've measured the BC's of bullets that had a ogive to base variation of .030". They came out of the same box. For all practical purpose they had the same BC. Sort to the tolerences that give you confidence. A range of .005" will not show up on the target. What you'll probably find is that your culls used for fouling shots and coarse sighters will shoot to same place.
Far more important is the effect the meplat has on the bullet. Irregular meplats cause variations in inflight bullet yaw resulting in variations in BC. </div></div>

If anyone's in a position to know this, Dave would be the one, and I'll gladly take back my measly $.02 where' his opinion is concerned.

I was told years ago that Sierra ran certain lots from three different presses and they all funneled into a single collection area. These were words from a Sierra technician, not hearsay, when I specifically called asking about variations in ogive to base length in 240 SMKs. This must be the "years ago" that Dave speaks of in his post. Whether the technician "misspoke" or things have changed. I also have a box of Berger 185 VLDs, same lot, that vary up to .030" in ogive to base length. I keep them just to show. It's nice to hear that manufacturers have stopped the common area collection practice, and Dave's words on lack of B.C. variation is sure going to save me some time. I guess some things do get better with time. Thanks for the comments Dave.

 

[scaxeman]

Re: sorting by ogive length -how close is close enough

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body">
Sort to the tolerences that give you confidence.
</div></div>

I'll definitely second that... 75% of the long-range game is between the shooter's ears! Does my weighing of each powder charge down to .02 grain (vs. .05 grain, or a *true* .1 grain) have an impact on MV, sD, etc? Probably not, but I have the utmost confidence in my loads... that's worth every minute spent loading.


Darrell

 

[DAVETOOLEY]

Re: sorting by ogive length -how close is close enough



Everyone who can plan a visit to one of the major manufactures should do so. They're great people. Mostly shooters like us and a picture is worth a thousand words. Are they human and make mistakes, sure but considering market pressures they do a great job for the quanity of bullets they produce. I've seen score cards attached to presses at Sierra that the total production was up in the millions. Think about that for a minute. That's a lot of bullets. We can whine about the few things we can measure or we can educate ourselves and understand what's important. Where can we gain the most with the least amount of anguish. In other words I'm getting older and lazier.
I've been shooting long and extreme long range for about 16 years now. When I started we were in a state of ignorant bliss. It was all about horsepower, faster was better. Coming from the short range benchrest world I started to question things. Hell my favorite 1000 yd bullet is a custom made 187 Gr. 30 cal. flat base. Nobody thought it would even get to the target. That bullet now holds two 10 shot small group records, one of which I shot. To shorten up a long story I got hold of a test that Dr. Ken Oehler and Larry Barthalome shot using 30 differnt bullets and they measured the BC's at the muzzle and 1000 yds. Nobody in the bullet business has liked me sense. I shouldn't say that I'm good friends with all of them. Anyway I got my own Oehler model 43 with acoustical screens and stared to verify the results that Ken and Larry got. This lead to talking to bullet manufactures and pointing out some of the issues we faced shooting at distance. What we have now are tightened up specs on ogive to base length, establishing more stringent controls over lot to lot variations. When major adjustments are made to a press a new lot # is established. Things are much much better than they used to be. Can they get better? Sure and a lot of the remaining issues are being addressed as time allows. The best thing I can say is they are listening and competiton is a good thing.