I've noticed when looking for brass within the Midwayusa site that when people rate the quality of the case they often downgrade because of weight variances that are miniscule. Why is this? How do minor weight variances affect accuracy? Just curious
Brass weight
- Thread starter komifornian
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Re: Brass weight
Then why are people so concerned about it? I just found it odd that it was even considered
Then why are people so concerned about it? I just found it odd that it was even considered
Re: Brass weight
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: komifornian</div><div class="ubbcode-body">Then why are people so concerned about it? I just found it odd that it was even considered </div></div>
Dunno....I used to think it mattered.
Tried and true load via OCW in un-weighed/un-sorted WW brass, which I hate BTW.....
Didn't even bother to chrono the workup until I needed some drop dope for 1k.
190 MK's in a custom 30-06, 1/4 MOA, at 500 yards, 1.280" center to center, during that chrono session.
Woulda been better but I pulled one....<grin>
I quit weighing brass, among other needless elements of case prep, when I found OCW, going on 10 years ago......
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: komifornian</div><div class="ubbcode-body">Then why are people so concerned about it? I just found it odd that it was even considered </div></div>
Dunno....I used to think it mattered.
Tried and true load via OCW in un-weighed/un-sorted WW brass, which I hate BTW.....
Didn't even bother to chrono the workup until I needed some drop dope for 1k.
190 MK's in a custom 30-06, 1/4 MOA, at 500 yards, 1.280" center to center, during that chrono session.
Woulda been better but I pulled one....<grin>
I quit weighing brass, among other needless elements of case prep, when I found OCW, going on 10 years ago......
Re: Brass weight
the thought process is that brass weight relates to wall thickness variations which leads to case capacity
the thought process is that brass weight relates to wall thickness variations which leads to case capacity
Re: Brass weight
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rb85cj7</div><div class="ubbcode-body">the thought process is that brass weight relates to wall thickness variations which leads to case capacity </div></div>
The above "load" performs the same across a full grain of consecutive powder weights, with the far upper end and the far lower end of that range producing just better than half MOA predictability (accuracy in net speak). That range of powder weights directly equates to a range of pressures that all fall into the same point of impact at any given place in the trajectory.
With the center of that range used and precisely weighed as the load, with zero +/- varience in powder weight, it by default incorporates a range of tolerance above and below that center point that applies to case capacity; among other things like a wide range of ambient temps, altitude, etc. Thus the ability to use un-weighed and un-sorted cases for the shooting I do.
I haven't ever tried to run the math because it doesn't matter enough to me to care about it, but it would seem that it would take a rather large amount of case capacity variance to throw me outside of my accuracy window enough to be above my 1 MOA overall standard for most CF rifles. Any varience within the same bag or box of brass is less than a mute point with OCW. I have once, for shits and giggles, loaded an OCW into different makes of brass to see for myself what Newberry's website says....accuracy was easily acceptable.
I have no idea why everyone doesn't load develope this way........
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rb85cj7</div><div class="ubbcode-body">the thought process is that brass weight relates to wall thickness variations which leads to case capacity </div></div>
The above "load" performs the same across a full grain of consecutive powder weights, with the far upper end and the far lower end of that range producing just better than half MOA predictability (accuracy in net speak). That range of powder weights directly equates to a range of pressures that all fall into the same point of impact at any given place in the trajectory.
With the center of that range used and precisely weighed as the load, with zero +/- varience in powder weight, it by default incorporates a range of tolerance above and below that center point that applies to case capacity; among other things like a wide range of ambient temps, altitude, etc. Thus the ability to use un-weighed and un-sorted cases for the shooting I do.
I haven't ever tried to run the math because it doesn't matter enough to me to care about it, but it would seem that it would take a rather large amount of case capacity variance to throw me outside of my accuracy window enough to be above my 1 MOA overall standard for most CF rifles. Any varience within the same bag or box of brass is less than a mute point with OCW. I have once, for shits and giggles, loaded an OCW into different makes of brass to see for myself what Newberry's website says....accuracy was easily acceptable.
I have no idea why everyone doesn't load develope this way........
Re: Brass weight
I do weigh sort match brass but only look for those pieces of brass that are way outside the weight range of the box/bag.
I have never really understood though why we weigh sort before prep. It seems that once I uniform primer pockets and deburr flash holes that the weights will all be very different.
I do weigh sort match brass but only look for those pieces of brass that are way outside the weight range of the box/bag.
I have never really understood though why we weigh sort before prep. It seems that once I uniform primer pockets and deburr flash holes that the weights will all be very different.
Re: Brass weight
Tried and true load via OCW in un-weighed/un-sorted WW brass, which I hate BTW.....
What does OCW stand for?
Tried and true load via OCW in un-weighed/un-sorted WW brass, which I hate BTW.....
What does OCW stand for?
Re: Brass weight
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: zuke</div><div class="ubbcode-body">Tried and true load via OCW in un-weighed/un-sorted WW brass, which I hate BTW.....
What does OCW stand for? </div></div>
Click the linky in my post...then live happily ever after.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: zuke</div><div class="ubbcode-body">Tried and true load via OCW in un-weighed/un-sorted WW brass, which I hate BTW.....
What does OCW stand for? </div></div>
Click the linky in my post...then live happily ever after.
Re: Brass weight
Strictly speaking, weight variances don't necessarily have to come from places that directly affect case volume - small things like a little fatter rim, etc. may cause case 'A' to weigh more than case 'B', while the differences in volume may or may not line up.
That said, if you do a decent sized statistical test you'll see that there is indeed *some* correlation between case weight and MV... but not a huge amount. Enough to be considered statistically 'significant', but thats not necessarily the same thing as saying it matters a whole lot in the real world.
Most people end up doing weight sorting because its quick and relatively painless - compared to the alternative, which involves plugging the flash hole, weighing, filling w/ liquid in a consistent and tedious manner, weighing again, etc. to establish the volume of the container (case). Not, necessarily, because sorting by weight is the best method.
For most purposes, most of the time... if you set up a load using something like the OCW process linked to above, your load will probably be 'tolerant' enough to withstand a little bit of variation in the case weight. For long-range competition, compared to the time/money invested in other stuff, it's not that big of a deal to sort cases by weight, and then 'batch' them accordingly, and/or use the 'tails' of the bell curve for sighters, load development, etc. and use the main body for matches. Thats pretty much what I do - first 100 goes into box 'A', next hundred go into box 'B', etc. The boxes taken from the 'ends' still usually have well less than 1 gn difference throughout, and the ones in the middle considerably less. I try to use the 'heavy' cases for load development. Its a cheap mental safety blanket, if nothing else
I will say that I have had a couple batches of Winchester .308 brass that had as much as a six or seven grain spread over relatively few cases (couple hundred), as opposed to two, maybe three grains spread over a couple 900-1000 case 'batches' for Lapua. Hindsight being what it is, I really wish I'd taken those Winchester cases and tested to see what sort of difference in internal volume and/or MV resulted from that much variation in weight.
Strictly speaking, weight variances don't necessarily have to come from places that directly affect case volume - small things like a little fatter rim, etc. may cause case 'A' to weigh more than case 'B', while the differences in volume may or may not line up.
That said, if you do a decent sized statistical test you'll see that there is indeed *some* correlation between case weight and MV... but not a huge amount. Enough to be considered statistically 'significant', but thats not necessarily the same thing as saying it matters a whole lot in the real world.
Most people end up doing weight sorting because its quick and relatively painless - compared to the alternative, which involves plugging the flash hole, weighing, filling w/ liquid in a consistent and tedious manner, weighing again, etc. to establish the volume of the container (case). Not, necessarily, because sorting by weight is the best method.
For most purposes, most of the time... if you set up a load using something like the OCW process linked to above, your load will probably be 'tolerant' enough to withstand a little bit of variation in the case weight. For long-range competition, compared to the time/money invested in other stuff, it's not that big of a deal to sort cases by weight, and then 'batch' them accordingly, and/or use the 'tails' of the bell curve for sighters, load development, etc. and use the main body for matches. Thats pretty much what I do - first 100 goes into box 'A', next hundred go into box 'B', etc. The boxes taken from the 'ends' still usually have well less than 1 gn difference throughout, and the ones in the middle considerably less. I try to use the 'heavy' cases for load development. Its a cheap mental safety blanket, if nothing else
I will say that I have had a couple batches of Winchester .308 brass that had as much as a six or seven grain spread over relatively few cases (couple hundred), as opposed to two, maybe three grains spread over a couple 900-1000 case 'batches' for Lapua. Hindsight being what it is, I really wish I'd taken those Winchester cases and tested to see what sort of difference in internal volume and/or MV resulted from that much variation in weight.
Re: Brass weight
I had thought about weight sorting brass and then I decided that I aint gonna chunk a piece of brass that costs approx. a dollar a piece cause it was a little off, and I aint gonna have a bunch of different boxes of ammo with different correction data corrolated to what the brass weighs so why bother? I think there are bigger fish to fry when it comes to put the boolit on the target way out yonder.
I had thought about weight sorting brass and then I decided that I aint gonna chunk a piece of brass that costs approx. a dollar a piece cause it was a little off, and I aint gonna have a bunch of different boxes of ammo with different correction data corrolated to what the brass weighs so why bother? I think there are bigger fish to fry when it comes to put the boolit on the target way out yonder.
