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Bullet Sorting, Again.......

Sumtoc

I've read most of the posts here re: bullet sorting but wanted to ask for the group's input on a specific challenge. I have a new 284 rifle headed my way and the 180 gr Bergers I'd prefer to start with are nowhere to be found. I am on several waiting lists but believe I will have to make do with other options for a while. So I bought 2 500 count boxes of the 7mm 180 gr SMKs. (They appear to be from different lots.) This rifle will be for 1K F-class.

The challenge is how best to sort, trim, point these to 1) ID the outliers and 2) improve consistency bullet to bullet.

I have read that many prefer to sort by OAL but it seems that since the meplats are so inconsistent that this would be wildly variable. So trim first to a uniform length? Or sort, trim and point in that order, keeping groups of similar length together? And what is the best (easiest but effective) sort group value? I know that attempting to point bullets with different OAL will not work well.

So what's the best path? I have a Sinclair bullet sorting stand that I can use for BTO or OAL, a good scale, Giraud 7mm meplat trimmer and Whidden pointing die.

Thanks
 
I'm no expert for sure, but I have experimented with some bullet sorting with my long range benchrest riflie. IMHO the best sort group value is BTO. Bart said BTO and he holds the group record for 600yrds. Larry Bryant had told me about a concentricity tester he has. I thought he was joking, but apperantly not. He advised me if you do one thing do BTO. Maybe try some custom hand made bullets if you get the chance.
 
Sumtoc said:
I've read most of the posts here re: bullet sorting but wanted to ask for the group's input on a specific challenge. I have a new 284 rifle headed my way and the 180 gr Bergers I'd prefer to start with are nowhere to be found. I am on several waiting lists but believe I will have to make do with other options for a while. So I bought 2 500 count boxes of the 7mm 180 gr SMKs. (They appear to be from different lots.) This rifle will be for 1K F-class.

The challenge is how best to sort, trim, point these to 1) ID the outliers and 2) improve consistency bullet to bullet.

I have read that many prefer to sort by OAL but it seems that since the meplats are so inconsistent that this would be wildly variable. So trim first to a uniform length? Or sort, trim and point in that order, keeping groups of similar length together? And what is the best (easiest but effective) sort group value? I know that attempting to point bullets with different OAL will not work well.

So what's the best path? I have a Sinclair bullet sorting stand that I can use for BTO or OAL, a good scale, Giraud 7mm meplat trimmer and Whidden pointing die.

Thanks
Click to expand...
I shoot the Sierra's in my 284win. 5 shots groups at 600 yards are .700 inches and 2 inch at 1000 yards. I would not do anything to those bullets or sort them.
 
Rogina, that is good to hear. I may shoot them unmolested first.

But if BTO sorted, what value is used between sorted piles?
 
The last 6mm Bergers I sorted by .0005 but in reality was probobly getting bleed over by .005 either way. Out of 500 I ended up with 4 piles and a few straglers on either end of that which I dumpted into thier respective neghibors. Haven't sorted the 1000 Barts yet. But then my groups are 2X that of the other guy... .7" at 600 and 2" at 1000 every time wow!
 
Sorting by OAL has at least a couple uses. First, I do not trim meplats prior to pointing. Sorting by OAL allows one to point directly. Although a jagged meplat can affect the OAL measurement, it will be pushed in closer to the bullet longitudinal/rotational axis after pointing, meaning its effect on weight distribution will be lessened. Also, slightly jagged meplats don't seem to make a difference in terms of the pointing process, in my hands. There is nothing wrong with trimming meplats first, but unless the bullets are sorted into OAL groups prior to trimming, you will end up with trimmed meplats of differing diameter prior to pointing them. This is also a potential source of variance in the pointing process. For example, if you trim the shortest and longest bullets from a box with a single trimmer setting, the trimmed (flattened) meplats will not be the same diameter. One will be larger than the other. As a result, the points on these two bullets will not end up exactly the same after the pointing die.

In addition, I have found Berger bullets to be fairly uniform with regard to their base-to-ogive and bearing surface dimensions. That means that sorting by OAL is sort of a "poor man's" Bob Green comparator, in that sorting bullets by OAL that have a consistent BTO dimension is really sorting by nose length. Bob's tool sorts bullets on the basis of distance between the two critical contact points on the bullet ogive for the seating process; i.e. the caliper insert contact point just above the bearing surface, and the seating die stem contact point further out toward the meplat. So sorting bullets by OAL can also have the effect of improving seating depth consistency, as long as they have fairly uniform BTO length.

The real question you're asking is "what are the causes of outliers?". I rather suspect that many have their own personal opinions about this, but in my mind, that is a question that cannot be answered reliably for a variety of reasons. If you cannot identify the exact cause for any outliers you may observe within a specific Lot of bullets, how can you sort for it?

When these bullets arrive, my suggestion would be to sort a group of at least 20-30 of them one time using several different means, such as OAL, BTO, weight, physical appearance (i.e. nose folds, jagged meplats, etc.), just to get a feel for the overall range associated with each sorting variable. You can then put together a sorting plan based that specific Lot of bullets and the amount of variance you observe within it for each sorting variable. Obviously, using a sorting variable that is already very consistent is unlikely to provide much improvement. I generally sort Bergers by OAL into length groups of .0015", then point them without trimming first. I have occasionally sorted them by weight, but that is really an exercise for someone with too much spare time on their hands; i.e. it doesn't do a whole lot for the bullets I use. Just keep in mind that a "perfect" sorting approach will leave you with a single bullet in each sorting group. That's not where you want to be, and a sorting approach carried to that extreme is not useful. It is usually possible to cull any gross outliers based on their external physical appearance and a single length sorting technique. At that point, you can determine how they shoot, which is the true indicator of how your sorting approach worked. If necessary, you can always modify your approach as you go.
 
I know its hard to get exactly what you want right now, but sorting bullet threads remind me why i live by a couple of rules on rifle selection- if they dont make lapua brass for it or easily formed from lapua (this now includes peterson brass), dont use it. If they dont make top shelf bullets that dont need sorted i also stay away. These mantras to live by will save you a ton of headaches. Imagine choosing to build a dasher back in the day and taking the short route and getting a norma dasher made. Sort the shitty brass and hope you can even get some later. How bout a 25cal anything? Build a gun around one bullet sierra may stop making for the guy when they get behind. My golden rule i try to get everybody to understand on top of these is… use what everybody else is using until you can do better. Why try to reinvent the wheel when you cant even get the most performance offered from the standard equipment?
 
rogina said:
I shoot the Sierra's in my 284win. 5 shots groups at 600 yards are .700 inches and 2 inch at 1000 yards. I would not do anything to those bullets or sort them.
Click to expand...
Are you holding for wind to get that 2” at 1000 yards or checking groups by holding center for every shot?
 
Jennb said:
Are you holding for wind to get that 2” at 1000 yards or checking groups by holding center for every shot?
Click to expand...
First of all, don't think that I shoot that small all of the time.At 600 and 1000 yards group size is dependant on the conditions. The day I shot that small I only had one-half moa of wind dialed in and the mirage was light and readable. It showed me what my rifle was capable of. I only shot that rifle twice at 600 and 1000 yards because I built it to shoot 2000 yards I shot it 3 times at 2000 yards with my best group at 11.5 inches with 9.5 moa of wind dialed in. It was a 3 shot group. I can't wait to shoot it in decent conditions. I don't have a smart phone but maybe I can get a friend to take pictures and post them next summer. Today it was 4 below zero. I will be glad to answer any other questions. I have shot shortrange benchrest for 27 years so anyone can check up on me as I have detected a bit of doubt.LOL
 
BTO includes base length, bearing length, and ogive radius.
You don't know which the sum of their variance is coming from, and none of them contribute as much to BC, given normal variances, as meplat diameter.

So if your going to normalize BC, then you want same meplat diameters.
You don't want to trim meplats to cause same OAL, but same meplat diameters.
For this, you need to remove as many non-meplat variables as possible.
That means taking a trimmer datum/reference from the ogive (not way back at the base), and so the ogives need to be qualified as same radius.
Use a BGC tool to qualify ogives: https://greensrifles.com/new-product-page
and a Hoover meplat trimmer: https://bullettipping.com/products/meplat-trimmer/
 
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