Weighing cases

cdoc42 · December 28, 2006, 12:00 PM

I have a 6mmPPC that was built for me by RW Hart. I do not bench rest shoot competitively, just for fun. With Norma cases, Berger 68gr bullets, BL-C(2) powder and CCI 400 primers I got a 4-shot, 100-yard group of .257". I've used H322 and Varget and no group with Bergers, Hornady VMax or Sierra Varminters has been less than 0.5".

I have never separated cases for hunting or target practice but I read that it should be done for really precise benchrest shooting.

I resized, trimmed, cleaned the primer pockets of 50 Norma cases. 20% weighed 90.5gr; 13%= 90.6gr. ONE was 80.0gr (!!) and 2 were 80.9gr. The rest ran the full gammit from 90.0 to 90.9gr.

How much of a spread is acceptable?

amamnn · December 28, 2006, 01:24 PM

If you want to shoot the kind of groups we see in competition, and you and your rifle are 100% then you're going to want to stop worrying so much about the weight of your cases and start culling them by volume. Weight is not an exact predictor of the capacity of your cases. Cases that weigh the same sometimes do not have the same capacity, and in extreme cases heavier brass may actually have more volume than lighter cases. You must be able to make every dimension of your cases uniform, Also, you are going to want to learn how to measure the density of your powder and figure your load variation based on the volume density relation. If you have a scale that weighs in grams it is a big help in making the calculations since 1 cc = 1 gram = 1mL of water (the density standard)

You will also want to ensure concentricity, bullet length from base to ogive and from base to tip (meplat) and a host of other variables that need to be controlled. Here is a good place or two to start---

http://www.6mmbr.com/index.html
http://www.benchrest.com/
http://nbrsa.benchrest.com/
http://www.sinclairintl.com/

6.5x.284tony · December 29, 2006, 04:13 AM

Do yourself a favor and try vv-133 powder and a 58 grain v-max bullet. This load seems to work very well for not only my ppc, but for several others that I load for. I personally use 30 grains with a cci br4 primer. Start a little lighter and work up of course! Benchrest like accuracy with a super explosive p-dog bullet.

Tony

cdoc42 · December 29, 2006, 04:02 PM

Thanks to both of you. Couldn't get back sooner because of hard drive crash.

I'll try the VV133 powder. I now use a 65gr VMax - didn't know they made a 58 gr.

Amann, if I did separate based on volume, what spread is considered acceptable? I would think new cases can be separated by volume but once fired, the insides are no longer equally clean and therefore volume discrepancies are going to happen. Is a difference of as much as 0.5ml acceptable or should it be less? One can, of course, go nuts with this because can one be sure every meniscus is equal?

amamnn · December 29, 2006, 06:08 PM

The method I use is the same as all the BR shooters I know. New brass is loaded with a fairly hot load and fired. (In making 6mm ppc from 220 russian I do this twice.) Then it is tumbled with walnut shell and scouring powder, reamed and FL sized without decapping. I know both Forster and Redding FL BR dies are capable of doing this; others may be as well. Depending upon the caliber, I use an RCBS precision mic or Wilson case gage to check shoulders and I also check head diameter and case (neck) length. Cases not found within .001" in any dimension are discarded except those which require neck trim only. Then I fill the case with water and measure the weight in grams.
(1 gram = 1 cc = 1 mL of water) Those cases which are +/- .025 grams or more are also discarded. I then proceed with neck thickness, concentricity and etc....... Other people may use different standards, but the method is the same.

December 28, 2006, 12:00 PM	#1
cdoc42 Senior Member Join Date: March 13, 2005 Location: Pennsylvania Posts: 1,687	Weighing cases I have a 6mmPPC that was built for me by RW Hart. I do not bench rest shoot competitively, just for fun. With Norma cases, Berger 68gr bullets, BL-C(2) powder and CCI 400 primers I got a 4-shot, 100-yard group of .257". I've used H322 and Varget and no group with Bergers, Hornady VMax or Sierra Varminters has been less than 0.5". I have never separated cases for hunting or target practice but I read that it should be done for really precise benchrest shooting. I resized, trimmed, cleaned the primer pockets of 50 Norma cases. 20% weighed 90.5gr; 13%= 90.6gr. ONE was 80.0gr (!!) and 2 were 80.9gr. The rest ran the full gammit from 90.0 to 90.9gr. How much of a spread is acceptable?

December 28, 2006, 01:24 PM	#2
amamnn Senior Member Join Date: May 13, 2006 Location: WA, the left armpit of the USA Posts: 1,323	If you want to shoot the kind of groups we see in competition, and you and your rifle are 100% then you're going to want to stop worrying so much about the weight of your cases and start culling them by volume. Weight is not an exact predictor of the capacity of your cases. Cases that weigh the same sometimes do not have the same capacity, and in extreme cases heavier brass may actually have more volume than lighter cases. You must be able to make every dimension of your cases uniform, Also, you are going to want to learn how to measure the density of your powder and figure your load variation based on the volume density relation. If you have a scale that weighs in grams it is a big help in making the calculations since 1 cc = 1 gram = 1mL of water (the density standard) You will also want to ensure concentricity, bullet length from base to ogive and from base to tip (meplat) and a host of other variables that need to be controlled. Here is a good place or two to start--- http://www.6mmbr.com/index.html http://www.benchrest.com/ http://nbrsa.benchrest.com/ http://www.sinclairintl.com/ __________________ "If the enemy is in range, so are you." - Infantry Journal

December 29, 2006, 06:08 PM	#5
amamnn Senior Member Join Date: May 13, 2006 Location: WA, the left armpit of the USA Posts: 1,323	The method I use is the same as all the BR shooters I know. New brass is loaded with a fairly hot load and fired. (In making 6mm ppc from 220 russian I do this twice.) Then it is tumbled with walnut shell and scouring powder, reamed and FL sized without decapping. I know both Forster and Redding FL BR dies are capable of doing this; others may be as well. Depending upon the caliber, I use an RCBS precision mic or Wilson case gage to check shoulders and I also check head diameter and case (neck) length. Cases not found within .001" in any dimension are discarded except those which require neck trim only. Then I fill the case with water and measure the weight in grams. (1 gram = 1 cc = 1 mL of water) Those cases which are +/- .025 grams or more are also discarded. I then proceed with neck thickness, concentricity and etc....... Other people may use different standards, but the method is the same. __________________ "If the enemy is in range, so are you." - Infantry Journal

December 29, 2006, 04:13 AM	#3
6.5x.284tony Member Join Date: December 26, 2006 Location: N.E. Colorado Posts: 15	Do yourself a favor and try vv-133 powder and a 58 grain v-max bullet. This load seems to work very well for not only my ppc, but for several others that I load for. I personally use 30 grains with a cci br4 primer. Start a little lighter and work up of course! Benchrest like accuracy with a super explosive p-dog bullet. Tony

December 29, 2006, 04:02 PM	#4
cdoc42 Senior Member Join Date: March 13, 2005 Location: Pennsylvania Posts: 1,687	Thanks to both of you. Couldn't get back sooner because of hard drive crash. I'll try the VV133 powder. I now use a 65gr VMax - didn't know they made a 58 gr. Amann, if I did separate based on volume, what spread is considered acceptable? I would think new cases can be separated by volume but once fired, the insides are no longer equally clean and therefore volume discrepancies are going to happen. Is a difference of as much as 0.5ml acceptable or should it be less? One can, of course, go nuts with this because can one be sure every meniscus is equal?