Weight sorting brass

[trevort]

Guys I decided to sort my 6 bra batch by weight. How much variance is allowable?

I have a distinct batch of 30 cases weighing from 123.4gn to 123.7gn and another batch of 30 weighing from 124.3 to 124.6 gns

I have 18 cases going from123.8 to 124.2 gn.

Then there 14 cases , 8 lower and 6 higher than those as the extremes.

Do I call those two sets of cases my match brass and the rest sighters or do I expand the weight tolerance and add those 18 cases to each batch depending on which group they weigh closest to?


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[macca]

Have you neck turned them Trev?
I like my record rounds to be exactly the same weight. 5 for LG.
The sighters can be off a little under or over.
If you haven't got 5 the same just choose 5 in sequence and shoot them lightest to heaviest.
Those are pretty tight groups weight wise.

[macca]

You can use the odds and sods for foulers and barrel warmers if you don't need that last sighter.
So you need 30 for record and maybe 30plus sighters.
I think you got it covered with or without the 18 in the middle.

[trevort]

Yeah they have been neck turned but I’m sure the weight variance is in my turning set up. I’ll measure the outside neck diameter when the pills are seated to confirm. And yes there are more than five the exact same weight


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[Camel]

Just drill a bit more out of the primer pockets and flash holes.

[LoneRider]

trev,weighing cases is the biggest waist of time anyone has ever come up with...
it means fark all compared to case capacity.

[macca]

trev,weighing cases is the biggest waist of time anyone has ever come up with...
it means fark all compared to case capacity.

True. But with lapua and rws cases the weight of the cases is very represenitive of the case capacity. I have checked it again and again and unless a case gives an elevation issue I don't need to do the h2o check.

[MISSED]

I have found that cases that weigh more have a smaller internal capacity.

[macca]

I have found that cases that weigh more have a smaller internal capacity.

Ditto. They also tend to handle more reloads .

[LoneRider]

theres a post on ozfclass about this very subject.
but tonight after a working bee and shooting and drinkin,im too saw to be farked looking for it.

[trevort]

The question is not about whether to weigh or not. It’s for those that do, what sort of variance is acceptable


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[Tony Z]

Trev the range you have them in is about right for a case that size. Under a half grain spread.
Lapua brass is very uniform so once prepped and formed, then trimmed and then weighed, you narrow down internal case capacity very closely.
If you shoot a group with those that are matched, then take the extreme end cases and shoot them, they will have a different POI. The further out you get, the more noticeable it will be.
Random chance could easily have them fall into the group. And they will just to piss you off. But when the numbers go against you, that one heavy or light case will kill the group.
Everyone i know that has ever shot small aggregates at 1K weight batches cases. How they get there may differ, but they all do it.

How i do it. Prep. Weigh. Shoot. Size. Trim. Skim the necks because they are never right on the first cut and need a fire form to level out the bumps and settle the neck shoulder junction. Weigh again. Done.
Cases that start of in one batch often move to another after this process. Only then am i fairly confident they have close internal capacities.
Record cases should have sighter cases closely matched. Sighter cases are just as if not more important than the record cases.

[trevort]

Thanks Tony and Macca


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[MISSED]

Very Good explanation Tony

[sometime shooter]

I also weight batch the finished loaded round call me crazy but it got a lot better for elevation issues out to 900 yards to the amount of .5 MOA for elevation. That is out of a Omark Action, 12 twist pac nor barrel.