average weight of cases

[gomerdog]

Okay, I have a question or two for those more knowledgeable than me, which should include everyone. I did a little activity this evening by weighing 6 30/06 Springfield cases of three different manufacturers: Remington, Winchester, and two lots of Greek military manufactured cases (HXP71 and HXP73), and then averaging the weight of those six cases, rounding off to the nearest grain. Winchester averaged 189 grains, Remington averaged 193 grains, HXP71 averaged 190 grains, and HXP73 averaged 188 grains. If the outside deminsions of the cases are the same and the weight is the same, are the volumes of the cases the same? In other words, if I have cases of two different manufactures that average the same weight, can I use the same load data? I had always assumed that cases of military manufacture had thicker case walls, were heavier, and therefore had less volume, so the load data had to be reduced. These two lots of military cases were not significantly different weights than the commercial cases. Can I use the same load data as commercial cases with these military cases? I'm puzzled.

[trotterlg]

If the material they are made from is the same and they are sized the same I would say the volume is close to the same.  You may want to put them on the scales, zero it out and then fill it with water and see if they hold the same weight of water.  If they do then they are the same.  Larry

[bluebayou]

I can't speak to the 30-06 cases, but some 7.62 cases that I have have thicker webs and therefore less internal capacity.  I understand that Lake City 5.56 holds less too, but I have no experience with military 5.56 cases. 

4 grains is not a lot of variation I wouldn't think.  Brass is an alloy, could the different manufacturers account for 4 grains of weight?  I don't know, not a metallurgist......As Larry said, the most accurate way would be to fill with water. 

Personally, I only separate cases and bullets by weight for one cartridge:  the 7mm-08.  This is because I spend more time shooting it, am more comfortable with it, and have two proven loads with my Remington.  All other factors are accounted for.  Die set up, OAL, necks turned, you name it.

Reloading is about ROI, Return on Investment, or diminishing returns however you want to phrase it.  I am sure that some would disagree, but after you (and your dies) are capable of consistent sizing and seating and you have uniform weighing of charges........it is all diminishing returns.  If your brass is sized right (remember, clean necks mean consistent necks), you seat to the same depth, and the powder is consistent then 90% of your possible accuracy has been achieved. 

Internal case dimensions, alignment in the chamber, necksizing, neck turning, weighing bullets (unless, of course you are buying cheap, inconsistent bullets to start), are all just icing on the cake.

I have ziploc bags of 7-08 brass separated by Remington headstamp for 120gr Hornady bullet and by Winchester headstamp for 160gr SGKs.  The bags are divided into lots in some kind of increment, say 162.0-162.5 grains, 162.6-163.0, etc.  It isn't something that I bother with in 223, 270, 308, or the pistol cartridges frankly because it is too much work.  The Remington is capable of astounding accuracy and I squeak as much as possible out of it. 

Whew.  Short answer, listen to Larry and fill with water.  Otherwise, just load them and be consistent

[carbineman]

Yes,different manufacturers cases weigh in at differing weights. For my 30-30 Topper the Remington cases and some WW Super cases weigh as much as 12 grains less than Federal and WW new manufactured cases, after trimming. This is only very important if you are really pushing the envelope on your loads. I use all the same weight for my hunting rounds so as to eliminate one variable. Back when I used to do alot of benchrest shooting, case weight along with outside neck turning was a big part of my case prep.

Another thing to check is to make sure case length or trim length is the same, as this could cause a real distinct variation in case weight.

As for your question if each case holds the same weight? I would think not, especially if you have trimmed to length all the cases. As the outside has been sized and the case trimmed, the difference is in the inside powder holding capacity of the case.

I would not worry about case weight and propellant charge weight unless you are at or near the top of your loadings published data. I would though try to use the same brand of cases if possible if a weight difference occurs in the cases. In other words use your
Brand X for 150 grain loads and your brand Y for 180 grain loads. That way it is easy to separate them for your different loadings

[McLernon]

I would not mix cases. I always eliminate the heaviest and lightest within a given make. First I weigh 15 cases and calculate the average.

Mc

[Mac11700]

This is only very important if you are really pushing the envelope on your loads.

Not entirely true...You don't have to push the envelope to see what a difference it can make with a mixed lot of varying weight brass can make...over a batch that is weighed perfectly...Perhaps for hunting ammo...where 2" groups are accepted or having those un-explained fliers happen doesn't matter...or where one isn't trying to achieve 1 hole groups...or is just hastily assembling something that goes bang for casual plinking or case forming...it might be...Your loading for a single shot...and you need to know exactly what your ammo will do....You may only get 1 shot...It may be a little time consuming to weigh them...but your accuracy will  improve...It will also make you more aware of your brass...because you will be paying more attention to it...For consistent accuracy from any given center fire load..and I mean where everything is repeatable with the same size groups and the same velocity...the same standard deviations at all ranges...then every component has to be the same...and the reloading technique has to be exactly the same...Having brass that varies all over the map in weight...you aren't never going to see consistency...day in and day out...For the casual reloader...they may never need to sort their brass...for those of us who want to create the most accurate ammo for our rifles...it is something that is necessary to do..

Mac

[gomerdog]

Thanks for all the replies. Everyone's viewpoint is interesting.

One of the reasons I ask these questions is because this brass has been reloaded one time, and frankly I'm getting better groups with the military brass than the commercial brass. My goal with this is to get the most accurate hunting load, not to max out my loads. I plan on using 180gr. or 200gr. bullets to hunt elk. Historically, my shots have been less than 100 yards, and moderate loads should suffice, but if I can use military brass and published data, I can eliminate the guesswork with finding a safe load in them. I would never consider mixing brass of different manufactures for load development.

I think I'll find the volume of the cases by doing what trotterlg suggested to be sure.

And another question: what is your favorite primer using R22 and 180gr. and 200gr. bullets?

Thanks,
Jeff

[Sir Charles deMoutonBlack]

8 grains of brass have the same volume as 1 grain of most smokeless powders.

You should know what your brass is like.  I agree with weighing some and keep records.  7.62 is notorious for military  brass being much heavier than sporting makes.  NORMA brass of all sorts is usually lighter.  Discount .223, like Federal Eagle, can vary a lot from case to case

[bluebayou]

Let me clarify-------I do separate cases by manufacturer. 

I totally agree with what Carbineman said:
Brand X for 150 grain loads and your brand Y for 180 grain loads. That way it is easy to separate them for your different loadings

I just don't segregate cases by weight normally. 

I did read a cool idea where some guy has a piece of poster board marked in grid squares with weights listed in .5 grain increments and he organizes bags of brass (same lot number of course) in a Gaussian distribution (Bell curve) kind of thing........TOO MUCH WORK.

[Graybeard]

A one percent difference in case weight is generally considered to be totally neglible but when it gets up to 3% I don't like it. Heavier cases definitely have less volume how much less does it take to be dangerous? I dunno but....

I once ignored the difference and used S&W headstamped .44 Magnum brass with a max load of W296 (the standard book load of 24.0 grains with a 240 grain bullet) and exploded a TC Contender in my hands with it. Yes I saw the difference in case fill but in my youthful ingnorance chose to use it anyway after verifying the case had nothing else in it and the powder weight was what it was supposed to be. Since then I've been a much more cautious hand loader.