When weighting cases what is acceptable range?

[DT400]

Those of you who are weighting their cases what is an acceptable variation in weight (either by % or gr) to be considered with-in range?
IE do you keep the weight to with-in .5gr either side of a target weight? IE any that weight 150.0 to 150.9 is OK or is it 1 gr either side IE 150.0 to 151.9 is OK?
I am weighting 6.5 Hornady brass. I know Hornady isn't the best but it's what I have on hand.
Out of 50 weighted I have them from 150.5 to (1) at 158 with most in the 150 to 152 range (3 gr variation).

Out of curiosity I weighed a 3"x3" post it note and it was 6.7gr...my variation from lowest to highest, not considering the 158 gr case) was less then that.

Darrell

 

[Canhunter35]

Take a permanent marker to that outlier then shoot it with the others at a 1000 and see if it vertically separates from the others.

 

[DT400]

Take a permanent marker to that outlier then shoot it with the others at a 1000 and see if it vertically separates from the others.

Doesn't quite answer my question and I can't tell if you are serious or being a smarta$$.
I don't have reasonable access to that sort of yardage, wish I did.
It was marked for other reasons and FWIW it was part of a .18" 100 yd grouping. I know 100 yds is very short, the ES for that group was 32fps but I don't know which one was this particular case. (I weighed them later out of curiosity).
I am curious what others consider an acceptable weight range.

Darrell

 

[ShtrRdy]

Case weight can be an indicator of case capacity. However, I had a learning experience this year when I bought some Lapua brass for the .308 Win that had a case weight spread more than I thought it should be. I wrote to Lapua and their reply was that they strive for consistent case capacity. So I did an experiment by firing the cases in my rifle and measuring the water weight from the heaviest brass and the lightest brass. The water weight was within 0.1 grain. After seeing that I don't worry about it when using Lapua brass.

Other brands of brass may be different. I would suggest firing a few of the heaviest and a few of the lightest and see how much difference in case volume they have by filling the fired case with water and measuring the water weight.

 

[DT400]

Case weight can be an indicator of case capacity. However, I had a learning experience this year when I bought some Lapua brass for the .308 Win that had a case weight spread more than I thought it should be. I wrote to Lapua and their reply was that they strive for consistent case capacity. So I did an experiment by firing the cases in my rifle and measuring the water weight from the heaviest brass and the lightest brass. The water weight was within 0.1 grain. After seeing that I don't worry about it when using Lapua brass.

Other brands of brass may be different. I would suggest firing a few of the heaviest and a few of the lightest and see how much difference in case volume they have by filling the fired case with water and measuring the water weight.

Makes sence I'll try that. What would an acceptable range of water weight be? Seems that water weight instead of case weight is a more accurate qualifier of consistency since the case weight could be in the base where may no directly translate into volume.

Darrell

 

[Canhunter35]

I wasn't being a smart ***, but the off weight case could be the culprit or it might not be, ime with 6.5cm and 308 the case weight has less bearing than one would think.
Uniform ur flash holes, anneal, weigh ur primers can really help tighten ur es.
So what I'm getting at without measuring your velocity difference you can't really know if that case is affecting it.
You could still use it as a dummy case or mark it to foul your bore, but I wouldn't worry about it

 

[J E Custom]

I prefer to stay within 1 grain batches. First I do a full length size and trim to the same length so that at least the outside of the cases are very close to the same. then I prep the primer flash hole on the inside to eliminate any fingernail or burr that might be there from the manufacture.

Then I start weighing the cases, separating them into 1 grain lots ( Like 187.0 to 187.9 and if I get one that weighs 188 grains It starts a new batch from 188.0 to 188.9. I normally end up with at least 2 batches, sometimes 3. Also many times I end up with 3 or 4 cases that are well beyond the batch weight and I use them for setting different bullets for that rifle by sizing with the expander ball removed to make a very tight bullet tension and include them in my die set for reference.

I also use the extra cases for test firing to check chamber dimensions and finish. (Nothing goes to waste).

If you go to the trouble to weight sort, 4 or 5 grain differences don't warrant the trouble and will not give you the results you want. Some premium cases will be very close and normally only have two different batches, If that.

J E CUSTOM

 

[DT400]

Pardon the violation.
I weighted 12 cases, The 6 lightest in the 150gr range, 5 in the 155 gr range (all but the single 158 were in this area) and the 12th was the 158.4 gr case, the heaviest.
The H2O weight range was 52.3 to 54.7 gr for 2.4 gr range. Now there was some some error on my part since each droplet out of a 22ga needle is pretty close to .1gr and I may have been over or under by a couple drops or 3. If I do this again I will get the bubble on top more accurate. Still way over the .1 gr ShtrRdy got from his Lapua brass.
To put 2.4 gr in perspective on a 6.5 CM case that 2.4 grains of H2O is the volume from case mouth .15" down the neck.
This was in trimmed, chamber fired brass, unsized with the spent primer in place.

Not to wait and see what my somewhat OCD brain will make me do with the 6.5....then the rest of the guns. This could get pricey.

Darrell

 

[DT400]

I prefer to stay within 1 grain batches. First I do a full length size and trim to the same length so that at least the outside of the cases are very close to the same. then I prep the primer flash hole on the inside to eliminate any fingernail or burr that might be there from the manufacture.

Then I start weighing the cases, separating them into 1 grain lots ( Like 187.0 to 187.9 and if I get one that weighs 188 grains It starts a new batch from 188.0 to 188.9. I normally end up with at least 2 batches, sometimes 3. Also many times I end up with 3 or 4 cases that are well beyond the batch weight and I use them for setting different bullets for that rifle by sizing with the expander ball removed to make a very tight bullet tension and include them in my die set for reference.

I also use the extra cases for test firing to check chamber dimensions and finish. (Nothing goes to waste).

If you go to the trouble to weight sort, 4 or 5 grain differences don't warrant the trouble and will not give you the results you want. Some premium cases will be very close and normally only have two different batches, If that.

J E CUSTOM

Thanks.
Once I hone in on a good recipe maybe for kicks I will write on each case the FPS and see what correlation there is between fps and volume then do some ballistic table work and see how it really affects me at the range I will likely be shooting.

Darrell

 

[ShtrRdy]

Pardon the violation.
I weighted 12 cases, The 6 lightest in the 150gr range, 5 in the 155 gr range (all but the single 158 were in this area) and the 12th was the 158.4 gr case, the heaviest.
The H2O weight range was 52.3 to 54.7 gr for 2.4 gr range. Now there was some some error on my part since each droplet out of a 22ga needle is pretty close to .1gr and I may have been over or under by a couple drops or 3. If I do this again I will get the bubble on top more accurate. Still way over the .1 gr ShtrRdy got from his Lapua brass.
To put 2.4 gr in perspective on a 6.5 CM case that 2.4 grains of H2O is the volume from case mouth .15" down the neck.
This was in trimmed, chamber fired brass, unsized with the spent primer in place.

Not to wait and see what my somewhat OCD brain will make me do with the 6.5....then the rest of the guns. This could get pricey.

Darrell

Since you have a 2.4 gr spread in volume h2o weight, next I would take a few pieces of brass with the largest volume and a few with the smallest volume and load them up to measure velocity.

 

[J E Custom]

Thanks.
Once I hone in on a good recipe maybe for kicks I will write on each case the FPS and see what correlation there is between fps and volume then do some ballistic table work and see how it really affects me at the range I will likely be shooting.

Darrell

Good Idea.

The reason I keep the batches separate is that some volumes just shoot better than Others. I shoot one batch until they wear out before starting on the next batch. Also If I want to find the best that the rifle will do, I sort 5 or 10 cases from one batch that weigh the same and load them for grouping. I also do the same with cartridge run out. What I am looking for is cases that weigh the same and loaded cartridges that have .000 run out. this will normally tell me what the rifle is capable of.

J E CUSTOM

 

[loaders_loft]

I like sorting a couple hundred cases, brand new from the bags. I weigh and sort, then starting at the lightest and working up, I group into fifty or hundred rounds (whatever the ammo box is) and keep those together throughout the life od the brass, never mixing them with other boxes. Usually a group will be less than 1 grain spread and the middle group may be less than half a grain. I do basically the same with match bullets.

 

[coyotezapper]

I prefer to stay within 1 grain batches. First I do a full length size and trim to the same length so that at least the outside of the cases are very close to the same. then I prep the primer flash hole on the inside to eliminate any fingernail or burr that might be there from the manufacture.

Then I start weighing the cases, separating them into 1 grain lots ( Like 187.0 to 187.9 and if I get one that weighs 188 grains It starts a new batch from 188.0 to 188.9. I normally end up with at least 2 batches, sometimes 3. Also many times I end up with 3 or 4 cases that are well beyond the batch weight and I use them for setting different bullets for that rifle by sizing with the expander ball removed to make a very tight bullet tension and include them in my die set for reference.

I also use the extra cases for test firing to check chamber dimensions and finish. (Nothing goes to waste).

If you go to the trouble to weight sort, 4 or 5 grain differences don't warrant the trouble and will not give you the results you want. Some premium cases will be very close and normally only have two different batches, If that.

J E CUSTOM

This^^^^

 

[Weaselthis]

I like sorting a couple hundred cases, brand new from the bags. I weigh and sort, then starting at the lightest and working up, I group into fifty or hundred rounds (whatever the ammo box is) and keep those together throughout the life od the brass, never mixing them with other boxes. Usually a group will be less than 1 grain spread and the middle group may be less than half a grain. I do basically the same with match bullets.

I follow a similar path, both for my match rifle and my hunting rifles and use smaller gallon ziploks to separate cases into ONE grain lots. I then use quarts to get them down to .1 grain lots that go into the gallon and stay together until pockets are gone. I will then mark each loaded round grouped together an put into one magazine for a match, i.e., for each distance at our club, 200,300,425,500,600,800,900,1000 will have either 3-12 rounds exactly weighing the same. Seems to help me. Get pretty consistent velocities MOST of the time. For hunting loads, I'll try to load up 20-30 for a trip. Seems overboard, I know, but I'm retired and got the time.