Author Topic: weighing cases (Read 637 times)

T/C nimrod · « **on:** March 19, 2003, 03:55:34 AM »

Has anyone every done research has to how much brass weight affects precision in a T/C Contender? I'm in the process of replacing some brass(30-30) for a 7-30 Waters, and have a 3-4 grain discrepancy in the lot of Remington brass I'm using. The previous brass was Winchester, and weighed +/- .3 grn. I'm already loaded for the research, just curious to see previous results and compare them to what I find.

KN · « **Reply #1 on:** March 19, 2003, 06:27:04 AM »

I did a little study at the range once with 223 ammo. 3 different case brands with identical loads. Zeroed with one load and checked the other 2 to it. One shot 3/4" higher and one shot 3/4" lower. Group size stayed the same but point of impact varied 1-1/2" from one case brand to the other. Convinced me to segregate brass. KN

T/C nimrod · « **Reply #2 on:** March 19, 2003, 09:05:31 AM »

I may have to clarify - I'm talking about case weight within the same headstamp. I try to keep my brass within +/- .3 grns. The new batch of Remington I'm working with (about 200 cases) is all over the place. I can't get enough of the same weight to satisfy my reloading requirements. So, I've segregated the cases into groups that are within +/- .3 grn. and span a 3-4 grain difference. I will be shooting each group and comparing them to the whole. I was curious if anyone else had ever done this to an accuracy standpoint?

KN · « **Reply #3 on:** March 19, 2003, 11:26:05 AM »

I didn't go int that much detail, Interesting question though. I'll have to weigh a bunch and see how much difference there is. KN

bsekf · « **Reply #4 on:** March 21, 2003, 04:06:24 AM »

I think every little bit helps. Go to a benchrest match and see what those guys do.

Duffy · « **Reply #5 on:** March 21, 2003, 08:41:27 AM »

I took a batch of Norma 270 brass and weighed out 25 that were within .1. Then I took them and water measured until I had about half that all were within .1 Everything was measured carefully when loaded to try and keep it on a even keel. The water measured ones had a ES of 9 fps and the ones that were just weighed had a ES of 28. The rest of the brass that had weights in excess of 1.5g difference had a ES of 80. That was enough to tell me that while just weighing helps, the water measuring, (a true PITA) and very time consuming is more accurate. The only thing is that the cases should be fireformed to your chamber and sized they way you normally do. This isn't written in stone just somthing that I tried.

T/C nimrod · « **Reply #6 on:** March 21, 2003, 10:23:37 AM »

Not to be stupid - what point in the process did you weigh the cases with water? Before the old primers were punched? Or are we putting something in the primer holes? Or......with the new primers installed? I weigh my cases after they have been resized/decapped and cleaned, without primers.

Duffy · « **Reply #7 on:** March 21, 2003, 05:55:28 PM »

That's not a stupid question. I simply resized the brass with a neck die and reinserted the spent primer. When I weighed a regular case I included the primer. I tried to keep everything as even as possable. All the flash holes were done and the primer pockets were cleaned up also. All the necks were trued up too. When you measure with water you are actually checking the internal volume of the case so sizing and once firing changes the internal volume. The best way is to once fire, size as you normally do, insert a spent primer, weigh the case, fill with water, strike it off even with the mouth and weigh again. Subtract smaller from larger and your done. Like I said time consuming but when your trying to tweek that last little bit........