Author Topic: A case study..... (Read 552 times)

JPH45 · « **on:** May 16, 2004, 04:25:16 AM »

Yesterday, a case I was using showed an interesting result. the 2 loads fired from it were 2395 fps and 2396 fps. Thes shots landed within 1/4" of each other. I immediately thought of that old rule of reloading.....sort you cases by weight. I've never really though that much about it. Yeah, different weight will mean a different volume, and that will equal a different pressure, blah, blah, blah. Just never thought it could make much difference in a hunting rifle. Most of my brass comes to me already loaded....I bought a factory box, and I don't mix that box up with other stuff, I reload that box untill it used up, then get another.

I bought this 30-30 Remington ammo about 10 years ago. It is their plain jane GREEN BOX 150 grain CoreLoct. Yesterday was the first day I was beginning to get pretty serious about my loading for the 30-30 and this event popped up. I culled it out of the group, and am going to reload it several more times to see what I get.

All this leads to......My scale is that nearly useless Lee scale that will only weigh up to 110 grains. (I've said nasty stuff about Richard under my breath several times...........) so how does one determine the volumetric differences between cases without a scale? I can envision the use of water, but it may be more relevant to fill the case level to the neck with powder, and weigh that charge. (That idea just came to me, see it does help to ramble endlessly with you guys) any other ideas?

So I'm off to do some case studies. Guess I'm even gonna try deburring the flash hole while I'm at it.

Wlscott · « **Reply #1 on:** May 16, 2004, 04:55:50 AM »

If you use powder, you'll have to be very consistant in how you pour the powder in the case. You can end up with one having more powder in it than the other one due to settling.

Use water.

Mac11700 · « **Reply #2 on:** May 16, 2004, 05:01:24 AM »

When evever I tried with water or powder..I just can't get close enough...so I use a scale to weigh the cases..I've found some large variances with just about all of the different cases I have for the 308...so far the Norma cases are the most consistant I bought..

Mac

handirifle · « **Reply #3 on:** May 16, 2004, 10:46:47 AM »

Ya know I tried that once, I had case weights all over the stinking scale. Never did figure out if it made much difference. It seems only common sense that it would but maybe someday I'll get a scale that makes it easy. The balance beam thing is VERY SLOW.

Fred M · « **Reply #4 on:** May 16, 2004, 08:22:39 PM »

Brass cases vary in weight from one brand to another. But brands do not vary all that much. I consider weighing brass a waste of time. Here is why.
8.6 gr of brass = 1gr of water in volume. Powder is .95gr.

Lets say you have a max variation of 5.0 gr in your batch of brass.
5:8.6= .58x.95=.55gr of powder. Most powder measures don't do any better with corse powder. A random sample will show variations to be a lot less specially with smaller cases.

a 1/2 gr of powder in hunting type cases will produce about 40 ft/sec.
Standard deviation will do that with a lot of strings even with charges being weight.

Correcting Flash hole variation, inconsistent primer seating and variation in the primer pocket depth will do much more for accuracy than weighing brass. Yes by all means deburr and bevel the flash hole on the inside.
K&M makes a nice little tool for that. It uniforms the flash hole,deburrs and bevels all at the same time. Fred M.