Weighing Cases
Weighing cases is becoming a more of an accepted step to sort new cases. It is a step done by many benchrest shooters, long-range shooters, and other competitors. Would we sort cases by weight for varmint hunting? Some would, but others might not waste the time. With the increasing acceptance of electronic digital scales and their decreasing prices, weighing cases is not as much of a chore as it used to be using balance beam scales. Excellent choices would include the RCBS scale, the MTM Mini-Scale, and my favorite, the AccuLab Scale. When handloaders weigh a batch of brass they generally segregate the brass into different shooting lots. They may end up with two or more batches of brass depending on the weight variance they experience. For our own personal shooting, a variance of 1.5% of case weight is an acceptable level for keeping cases in a shooting lot. Each handloader may set different criteria for sorting cases by weight, and some may not determine the variance spread until they have seen how the case lot distributes by weight.
One of the reasons for using case weight as sorting criteria is that case weight variances can be indicative of differences in body wall thickness or in web thickness. Large variances in body wall thickness can affect case capacity, which can lead to pressure variances that will affect down range performance.
If we are selecting cases for competition shooting, especially long-range competition, we may weigh every case in the batch. If we are preparing cases for a hunting rifle, we may weigh a sample of the cases to see if there is a large variance between case weights. If we are sorting through 100 cases we might weigh 10 cases and check the extreme weight variance. If the variance is greater than 3% (assuming +/- 1.5% is our pre-determined criteria), than we may want to weigh some additional cases.
There is more than one way to go about weighing cases to sort into batches. With an electronic scale, it goes rather quickly once you are setup. Two methods we have used to weigh cases are the “tape method” and the “bin method”. The “tape” method is done by applying a piece of masking tape to a fairly large surface. Weigh a few pieces (3 or 4); these will hopefully tell you where to start writing weights on the piece of tape. Write weights down in increments of 0.1 grain. As you weigh your cases sit them behind the weight designated on the tape. You should begin to see a bell curve develop with the variances in case weight. It is rather easy to make up some groups of 100 cases that were within a variance of 1.0% in weight. These cases will stay together as a group unless further sorting separates them. The advantage of using the tape method is that you can easily count and see the distribution of the cases across the weight variance range. It makes grouping cases much easier. The disadvantage is that trying to stand all of the cases up without knocking them down is like playing dominos. A great tip from a customer who took our procedure a step further is to use one of those overhead light panels with a grid surface. This helps keep the cases sorted and standing up. It will work for cartridges having a case head of 0.572” or smaller (except for cases like a 30-378 that won’t quite fit in because of the belt). The two photos below show 
the distribution of a batch of 100 Norma brand, 22-250 Remington cases and a 100 piece batch of Remington brand, 22-250 Remington cases. I would definitely use the Norma as it stands.
If this was a cartridge I was shooting long-range, I might think about culling some of the Remington cases on the extreme ends of the weight distribution. The Remington batch is actually a pretty good batch; it just looks bad next to the Norma. The downside is you have to pay over twice as much for the Norma cases versus the Remington or Winchester cases. Incidentally, in these two batches the Norma cases were about 8 grains heavier than the Remington brand.
A second and faster method of sorting cases by weight is to buy some cheap plastic bins at the hardware store or grocery store. Use these to throw brass into as you are weighing. 
Put a piece of tape on each bin with the weight (again in 0.1 grain increments) and begin sorting. This method’s big advantages are that it goes much quicker and you don’t have to worry about knocking the cases over. The only disadvantage is that after sorting you need to count the cases in each bin to determine the distribution of weights. I prefer using a panel.
Both of these methods work fine for weigh-sorting brass. What you establish as your criteria for grouping brass into firing lots is up to you. We have weighed batches where we simply culled the pieces on the extreme end of the spread and ended up with one nice sized batch. Weighing cases isn’t critical for every type of shooting, but it can have an impact with respect to certain cases. I know one shooter who found that he benefited greatly when sorting his 22 Hornet cases by weight. He felt accuracy was directly affected by the variances in case capacity.
January 16th, 2009 at 12:06 pm
I enjoyed reading the article and would pass along a personal experience on the subject.
I have 3 Varmint Rifles, a 6 X47 Lapua, a 204 Ruger and a 223 Rem. I use Lapua Brass on the Lapua, Nosler and Norma on the 204 and Remington and Winchester in the 223.
In the Lapua Brass, over a total of 300 cases from 2 lots, the variance has been less than .15 grams, in the Nosler and Norma, with 500 cases, less than .25. The Remington has varied as much as 1 Gram, a 400% – incremental difference.
These results change my purchasing habits on brass, if Lapua makes it that is my first choice, (even to resizing 30/06 for my 25/06), if Nosler is available that is the second choice and I will use Remington and Winchester only as a last resort, after sorting.
January 16th, 2009 at 3:52 pm
OR— you can use your loading blocks if you have more than one or two.
January 16th, 2009 at 4:14 pm
Very interesting article. I am going to try this. Question – do you weigh sort only after neck sizing, length trimming, and trimming oor the primer and firing hole. Then any weight delta will be due presumeably to the variation in cartridge wall thickness.
January 16th, 2009 at 6:08 pm
First off I’d like to say how much I enjoy this e-newsletter and your website in general. I’ve learnt a lot from them. I have bought a fair bit over the years from you and the service has been first class in all cases, especially given the logistics (I live in Australia).
A question about sorting by weight. Should you do any case prep first (such as case trimming to get length consistent, flash hole deburring) before weighing or is it just too much work? I ask this because these are controllable variables that may skew the results. Maybe I should trial a batch and see?
January 16th, 2009 at 6:53 pm
Before weighng cases, wouldn’t it be best to trim to length? I have noticed a large variation in new case length and this has got to affect weight.
January 16th, 2009 at 9:09 pm
Enjoyed this edition of the “Reloading Press”; keep up the good work.
January 16th, 2009 at 9:14 pm
Great article! I hadn’t thought of the tape method or the bin method, nor have I used the sample approach. I number each case, weigh and record the weight, discarding those that fall outside of the criteria for keeping- very tedious.
January 17th, 2009 at 1:33 am
Great tips !! Thank you
January 17th, 2009 at 11:02 am
I am already enjoying the news letter, thanks for the information. I have the same question wouldn’t you turn the necks trim the cases and square the heads first and in what order? also if you were squaring the heads it seems like there would be a lot of weight lost and would affect your head space and make some of the cases have shorter heads with longer necks, is there an exact protocol for these steps.
January 17th, 2009 at 11:29 am
Thank You Very Much.. Great Article..
January 17th, 2009 at 12:50 pm
With any batch of new cases, I trim each case before weighing. I find this reduces much of the varience in case weights. Regardless, this article is a good reminder of why weighing before loading can pay dividends later.
January 18th, 2009 at 12:34 pm
Hi All
I am a 1K yd benchrest shooter and we all weigh cases as in the article as we have found from testing there is definately an improvement in accuracy when your cases are batched by weight.
In answer to some of the questions above it is thought best by most benchrest shooters to size, trim length, turn necks and uniform primer and flashole pockets usually in this order prior to batching.
January 18th, 2009 at 4:25 pm
Keep up the good work guys. The tech. tip on weighing cases was a solid reminder on an all too often over looked step in the reloading process.
Keep them tips coming!
January 23rd, 2009 at 3:16 pm
Good artilce and some great tips for the reloader. Once I have sorted the brass into lots I stamp the bottom of the case using an automatic center punch, the punch mark is placed in different locations, using the case stamp as reference points. ie for lot one the stamp mark is after the “a” Lapua. Works real easy and the punch can be adjusted to give a very light mark on the rim.
June 17th, 2009 at 1:40 am
Great article, I especially liked the punch line at the end about the Hornet, that is exactly what I have been working on. I just sorted about 200 cases of two brands and the tape was a great way to do it. Another shooter told me he uses 1 grain spread for cases and 1/2 grain spread for bullets. The 3% rule you shared is actually the equivalent to the one grain, so it worked perfectly. SO hopefully I am on my way to more accuracy for my Hornet. Thanks again.
July 16th, 2009 at 9:14 am
When preparing to reloading some 223 rounds my brother and I decided to sort the cases by weight after all case preparation was finished.
We started off with a Lyman DPS 1200 and when I rechecked some of the readings were up to .4 grains different than what the cases checked a few minutes earlier. Thinking it was the scale I got my RCBS Rangemaster and sorted them again, similar results !!
We tried it zeroing on a case then sorting by weight difference and by zeroing the scale and separating by actual weight. We compared between scales and found they often differed by .2 and once in a while .3 grains.My brothers reloading room is draft free with a very solid and level bench.
After contacting Lyman, RCBS and Ohaus I have gathered the following information:
Most of these scales use strain gauge technology. . Learn more on strain gauges at http://www.sensorland.com/HowPage002.html
The strain gauge can give you good weighing results for static loads, but can drift much more due to temperature variations which may occur by just by using the scale. Especially those with the feed motor (like the DPS 1200) which will generate heat just from being used. Zero often, and calibrate when suggested by the system. Any voltage fluctuation may confuse the electronics into thinking the load has changed.
These scales are VERY sensitive and will detect any movement which could cause the strain gauge to flex at all under it’s load (including the empty pan). Light drafts can be caused by the movement of your hand while loading the scale and will affect the reading, but should stabilize once the ‘breeze’ subsides. Test it – it’s cool!
Any vibration of the scale will affect the reading if it causes the scale to move at all. Another fun test.
AC Line noise will affect the scales, a line conditioner is an excellent investment.
Fluorescent lights are not a problem unless they are close to the scale, in the 2 to 3′ range.
Cell phones can cause interference with electronics, all recommend that they be turned off if near the scale (10ft). My scales went crazy whenever my cell was in use (dialing – talking – etc.) and did ‘wander’ more when it was just in my pocket turned on. We had to move it 10 ft away before it stopped bothering the scales.
Both RCBS and Lyman offered to evaluate the scales for me, I paid shipping, which I will do, and am grateful for since they are not brand new. Both then replied that the scales were out of warranty and they only offered to sell me new scales – I took the offer and got a new DPS 1200.
You’ll see get better performance, linearity and repeatability with an electromagnetic weigh sensor which cost a whole lot more, and takes us back to the “Does it really make a difference?”
I have received a lot of feedback asking “What am I thinking and why worry about it so much?”. Well the answers are simple in my mind. The pursuit of perfection is why I got into the hobby of shooting, smithing and reloading. It’s fun to be able to make one hole. When I screw up and miss blow a group, I like to be able to prove to myself that the variation was the shooter (me) and not the other variables. For me this is fun.
The other concern I have and wanted to understand is regarding loading pistol rounds where a tenth of a grain is much more of an issue than with my 25-06. My brother and I load 17 Mach IV (17 Fireball) and 460 Rowland cartridges which are by nature fairly hot and sensitive to load variation. A couple of tenths of a grain will make a significant difference. (If you haven’t shot a 460 Rowland in a 1911, you have to try it, Clark makes great barrels and they shoot great. http://www.clarkcustomguns.com/rowland.htm )
I have purchased an Acclab VIC 123 which reads to .01 grains and have found it to be extremely accurate, precise and reliable. While it reads to 2 decimal points (.01 gr) I can not use that digit, since the scale does have some measurement error as an electronic / mechanical device. But I can ALWAYS rely on the tenths (.1gr) reading with confidence. .1grain is as precise as I need to be for any of my activities and this ability has allowed me to significantly shrink groups. After trying different RCBS, Ohaus and Lyman DPS scales, which all read to .1grain, NONE of them were reliable for measuring or sorting to closer than 1 grain.