OzFclass

Variations in wall thickness are one of the biggest enemies. ie; wall thickness varying around the case. Upon firing the case will stretch unevenly. A banana effect if you like.

I use a Juenke comparitor to weed out these cases. Some batches of Lapua 6.5-284 had big variations a couple of years ago.

Hope this helps
Cameron

cameron,
thosse juanke things would be good to have, but i believe they are quite dear.
one good thing about going back to 2 sighters is that if 2 cases out of every 50 fail the group test, they can be culled.
bruce moulds.

G day Bruce. I think the old bloke in the states has stopped making the Juenke. Pity.
Majority of Lapua 284 brass comes up good now days. I don't weigh cases. Do a visual inspection, run over Juenke, prepare..neck turn etc.. fire form then cull suspect ones at club shoots.

Cameron

You could take it a little further Bruce and look at the volume (H20) for each group of brass. I undertook this exercise in reloading 'zen' once with a new batch of 308 lapua...tedious but character building. actually, I think it borders on insane. I wish had the time for this sort of crap nowdays.

Used the same spent primer as the plug and weighed each case and the variation was negligible in keeping with the 2 groups separated by the initial weigh - did it translate to anything palpable on the target? Not that I could discern...so I settled with buying Lapua, uniforming pockets and flash holes and weighing bullets and powder instead

hi simon,
i hear you got more shots on the target than paul.
bruce.

Hah...not many more with the 308 in a good old MBRC howler

Simon C wrote:You could take it a little further Bruce and look at the volume (H20) for each group of brass. I undertook this exercise in reloading 'zen' once with a new batch of 308 lapua...tedious but character building. actually, I think it borders on insane. I wish had the time for this sort of crap nowdays.

Amazing how an idea can be shown to be incorrect, but people just ignore it.

Woody_rod wrote:

Simon C wrote:You could take it a little further Bruce and look at the volume (H20) for each group of brass. I undertook this exercise in reloading 'zen' once with a new batch of 308 lapua...tedious but character building. actually, I think it borders on insane. I wish had the time for this sort of crap nowdays.

Amazing how an idea can be shown to be incorrect, but people just ignore it.

Hi Woody,

I dont know about it being incorrect - the variance was in line with the results i got from weighing the raw brass in the first instance. My point was that it didnt really give me any extra info that the inital weigh did (for Lapua that is)

I think the bit extra for lapua cases is worth it when u weigh up the time u may need to put in to feel good about using less consisent brass.

G'day All,
basically when do you weigh brass; before you prep them or after and is there a point? That is, is there a significant measurable improvement in scores or group size?

I use to weight brass for Benchrest but no longer do. The most important issues for me are de-burr the flash hole, uniform the primer pocket, neck turn the necks (even with no turn chambers) for uniformity of bullet "grip" and keep all the case OAL for less than 5 thou variation and then preferably all the same length.

After that practice, practice, practice. You are much better off shooting than weighing cases........or even writing about it on online forums!

Shooting in match conditions will do more to improve scores that the weight of your brass me thinks.......

hope this helps

Cheerio Ned

Hi Bruce, wes Simon got heaps more on paper than me, he even scored heaps more than me. That will bring us to another topic about projectile variance.

But on your subject about weighing cases, I do it and for me I batch with 1gn variance.

I nearly made a big BOO BOO, I could not get any 8X68S cases, but Peter Van Muers offered me some 6.5x68S cases.
I proceded to prep them for fire forming, then the little bell went off, so I weighed some 6.5 and 8mm cases. There was a 3 grain diference in case weight.
That could have caused problems when you run near max load.

Also, if you use X brand brass and need more and you can not get X brand so you buy Y brand, check the weight diference as your loads will need changing if there is a variance in brass weight.

Just my experiences.

Cheers
Paul

ned kelly wrote:G'day All,
basically when do you weigh brass; before you prep them or after and is there a point? That is, is there a significant measurable improvement in scores or group size?

I use to weight brass for Benchrest but no longer do. The most important issues for me are de-burr the flash hole, uniform the primer pocket, neck turn the necks (even with no turn chambers) for uniformity of bullet "grip" and keep all the case OAL for less than 5 thou variation and then preferably all the same length.

After that practice, practice, practice. You are much better off shooting than weighing cases........or even writing about it on online forums!

Shooting in match conditions will do more to improve scores that the weight of your brass me thinks.......

hope this helps

Cheerio Ned

True, however I think there is some benefit in having a very consistent set of cases for use at 700m and beyond.

My usual practice is to mike case necks after running them over the mandrel and segregate by this variation (which has out of 3 batches of 308 Lapua and 2 batches of 6BR Lapua yielded 3 distinct groups each time).

I mark the rim edge of each case with a small file with 1, 2 or 3 nicks depending on their consistency group....1 being the best and 3 the worst. I then skim the necks and uniform the pockets and they were ready to go. This process is somewhat onerous but it only happens once for me at the start. I'm happy with that amount of input so thats why I dont weigh brass as a matter of course - I have done it on the odd occasion and as I mentioned b4, looked at the H20 capacity.

Those cases in group 1 have always performed well at the longs from a vertical point of view in my Std gun. I feel better knowing that the neck tension is consistent and that I think is more important for me. It may not be the same for others but like Elton John said: "What ever get u thru the night, is all right, is all right" although I suspect he hasnt got much of an interest in target shooting

I have weighed brass, and still would, but only when necessary. If I don't have a velocity spread problem, then case capacity variation (which is normally indicated by case weight variation) is not a concern, along with several other things : variable neck tension, inaccurate powder charges, unsuitable powder/primer, bad firing pin spring, inconsistent projectile diameters. If muzzle velocity ES is good, no need to check any of them.

More about the value of velocity spread testing :

If velocity spread is good, and LR elevation is bad, then projectile consistency (variable BC and to a lesser extent weight) is suspect, along with equipment (barrel, scope, rifle, rests) problems.

If velocity spread is good, and short range accuracy is poor, then its very likely to be an equipment problem.

Just my opinion. YMMV.

Alan

reply to M12LRPV and Barry Davies

"You don't because you don't know where the variation manifests itself in the case.
That is why the only way to really do it is to fill each case with water and weigh how much water you can get into it.
Personally I couldn't be stuffed. Maybe one day though, when I can figure out an easy way to plug the primer pockets "

What I have experienced, the majority of weight variation stems from base thickness. Therefore if one measures base thicknes it will relate to how much powder fits into that case.
Make a small rod with a pilot. The pilot fits in fire hole, the rod sits above the case mouth. Place under dial gauge and read the variation between cases and batch accordingly.

Regards

bolster55 wrote:What I have experienced, the majority of weight variation stems from base thickness. Therefore if one measures base thicknes it will relate to how much powder fits into that case.
Make a small rod with a pilot. The pilot fits in fire hole, the rod sits above the case mouth. Place under dial gauge and read the variation between cases and batch accordingly.

If two cases are the same mass (weight), but one has a slightly thicker base, how is this going to show you that there will be a change in volume?

Hello Woody_rod,
My mistake, try bridge thickness, not base thickness.
If cases are headed with different heading punches and heading dies, volume will change.

Regards