Weighing Unprimed Cases

Mad_Max · June 3, 2017, 04:03 PM

I've been told to weigh my cases for consistency in groups. So I fire formed and neck sized and trimmed all the cases to the same length and de-burred them and cleaned the primer pockets and then cleaned the brass in RCBS corn cob media and then weighed them and here are the results of 57 casings with a 3.2 GR. difference from the lightest to the heaviest case.

.308 Win. Remington Case Weight

165.2 165.4 165.4 165.4 165.5

165.5 165.6 165.7 165.7 165.8

165.8 165.9 165.9 165.9 165.9

165.9 166.0 166.1 166.1 166.1

166.1 166.2 166.4 166.4 166.6

166.7 166.7 166.7 166.7 166.8

166.9 166.9 167.0 167.0 167.1

167.1 167.2 167.2 167.2 167.2

167.2 167.3 167.3 167.4 167.4

167.4 167.5 167.5 167.6 167.6

167.8 167.8 167.8 168.0 168.2

168.2 168.4

Berserker · June 3, 2017, 04:24 PM

The reason to do this, I believe, is to check for volume. How much variance you accept, depends on how far you shoot.

Mad_Max · June 3, 2017, 04:32 PM

I would think that the closer the cases weigh to each other the more consistency you'd have in shooting. I shoot as far as 600 yards. Never tried 1,000 yards.

Berserker · June 3, 2017, 06:30 PM

I believe, the belief is if they weight more, they have more volume, which effects pressure. You want to be consistant. Filling with powder, then measuring powder would take forever. Some champion benchrest shooters might though.

Higher end brass like Laupa or Norma, is probably more consitant. I shoot lots of remington. I have seen a difference, but I am not shooting 600 yards. My home range is 100.

jmorris · June 3, 2017, 06:35 PM

To see if it is worth the time take the 10 closest cases and load them and 5 of the lightest and 5 of the heaviest and shoot two 10 shot groups.

If one looks like a shotgun pattern and the other one hole then you'll know it's worth it, if you can't tell the difference don't waste the time in the future.

jmorris · June 3, 2017, 06:36 PM

Quote:

I believe, the belief is if they weight more, they have more volume, which effects pressure.

If the mass of the material is the same and they have the same external dimensions, any additional weight would reduce internal dimensions/volume. Of course any difference in volume will effect pressure, dependent on variables.

Berserker · June 3, 2017, 06:44 PM

Ya, that is what I said. Different weight, different volume, different pressure.

Berserker · June 3, 2017, 06:46 PM

If you read up on long range shooting, some folks want every round identical. Longrangehunting, is a good place to read up, and tons of articles too.

scatterbrain · June 4, 2017, 11:47 AM

In my experience if I take 5 or 10 of the lightest or 5 or 10 of the heaviest, I will still get consistent groups. It's when I take some light cases and mix with heavy cases that groups spread. I have separated cases into one grain batches and shot over the chrono and got the average velocity for each group. The group size will be fairly equal, but average velocity will increase by about one percent for each one grain variance of the average group weight. In my experience what the case weight is is not as important as all being the same weight in that group.

Gary Wells · June 4, 2017, 12:52 PM

MAD MAX: Do you currently weigh out & segregate your projectiles?
Do you currently reload only 1 case brand or multiple brands?
I would have a tendency to believe that you would see a difference in
accuracy & / or precision @ 600 yds weighing & segregating both the
jectile & the cases. pro

Mad_Max · June 5, 2017, 02:25 PM

Yes I weigh my bullets also and I'm going to separate them and match them up & chronograph them and also check for group size.

Gary Wells · June 5, 2017, 02:52 PM

MM, please post up the results. This should make for a very interesting & informative experiment. I'm thinking that at 600 yds it will make a noticeable difference.

June 3, 2017, 04:03 PM	#1
Mad_Max Junior Member Join Date: May 29, 2017 Posts: 5	Weighing Unprimed Cases I've been told to weigh my cases for consistency in groups. So I fire formed and neck sized and trimmed all the cases to the same length and de-burred them and cleaned the primer pockets and then cleaned the brass in RCBS corn cob media and then weighed them and here are the results of 57 casings with a 3.2 GR. difference from the lightest to the heaviest case. .308 Win. Remington Case Weight 165.2 165.4 165.4 165.4 165.5 165.5 165.6 165.7 165.7 165.8 165.8 165.9 165.9 165.9 165.9 165.9 166.0 166.1 166.1 166.1 166.1 166.2 166.4 166.4 166.6 166.7 166.7 166.7 166.7 166.8 166.9 166.9 167.0 167.0 167.1 167.1 167.2 167.2 167.2 167.2 167.2 167.3 167.3 167.4 167.4 167.4 167.5 167.5 167.6 167.6 167.8 167.8 167.8 168.0 168.2 168.2 168.4

June 3, 2017, 04:32 PM	#3
Mad_Max Junior Member Join Date: May 29, 2017 Posts: 5	Weighing Cases I would think that the closer the cases weigh to each other the more consistency you'd have in shooting. I shoot as far as 600 yards. Never tried 1,000 yards.

June 4, 2017, 11:47 AM	#9
scatterbrain Senior Member Join Date: February 7, 2015 Posts: 178	Weight Grouping In my experience if I take 5 or 10 of the lightest or 5 or 10 of the heaviest, I will still get consistent groups. It's when I take some light cases and mix with heavy cases that groups spread. I have separated cases into one grain batches and shot over the chrono and got the average velocity for each group. The group size will be fairly equal, but average velocity will increase by about one percent for each one grain variance of the average group weight. In my experience what the case weight is is not as important as all being the same weight in that group.

June 5, 2017, 02:25 PM	#11
Mad_Max Junior Member Join Date: May 29, 2017 Posts: 5	Weighing Cases Yes I weigh my bullets also and I'm going to separate them and match them up & chronograph them and also check for group size.

June 3, 2017, 04:24 PM	#2
Berserker Junior member Join Date: April 6, 2015 Location: WI & UP Posts: 284	The reason to do this, I believe, is to check for volume. How much variance you accept, depends on how far you shoot.

June 3, 2017, 06:30 PM	#4
Berserker Junior member Join Date: April 6, 2015 Location: WI & UP Posts: 284	I believe, the belief is if they weight more, they have more volume, which effects pressure. You want to be consistant. Filling with powder, then measuring powder would take forever. Some champion benchrest shooters might though. Higher end brass like Laupa or Norma, is probably more consitant. I shoot lots of remington. I have seen a difference, but I am not shooting 600 yards. My home range is 100.

June 3, 2017, 06:35 PM	#5
jmorris Senior Member Join Date: November 22, 2006 Posts: 3,078	To see if it is worth the time take the 10 closest cases and load them and 5 of the lightest and 5 of the heaviest and shoot two 10 shot groups. If one looks like a shotgun pattern and the other one hole then you'll know it's worth it, if you can't tell the difference don't waste the time in the future.

June 3, 2017, 06:44 PM	#7
Berserker Junior member Join Date: April 6, 2015 Location: WI & UP Posts: 284	Ya, that is what I said. Different weight, different volume, different pressure.

June 3, 2017, 06:46 PM	#8
Berserker Junior member Join Date: April 6, 2015 Location: WI & UP Posts: 284	If you read up on long range shooting, some folks want every round identical. Longrangehunting, is a good place to read up, and tons of articles too.

June 4, 2017, 12:52 PM	#10
Gary Wells Senior Member Join Date: August 22, 2009 Posts: 180	MAD MAX: Do you currently weigh out & segregate your projectiles? Do you currently reload only 1 case brand or multiple brands? I would have a tendency to believe that you would see a difference in accuracy & / or precision @ 600 yds weighing & segregating both the jectile & the cases. pro

June 5, 2017, 02:52 PM	#12
Gary Wells Senior Member Join Date: August 22, 2009 Posts: 180	MM, please post up the results. This should make for a very interesting & informative experiment. I'm thinking that at 600 yds it will make a noticeable difference.