Home Forums Hunting & Shooting Ask The Gunwriters charge weights

MD, despite knowing better, I got to thinking. (dangerous, I know)
If two different brands of brass vary by 4% in weight, should a 4% powder weight adjustment be appropriate?
(Betting not, but thought I'd ask)

Mark, I'm not the expert on this, but will pose a few thoughts. Just weighed some .30-30 brass, same brand and the first 2 I weighed had a difference of 3.55%. The heavy one was 139.5 grains. Fired in same chamber, prepped to include trim for OAL. The affect on peak pressure is, with all else equal, a matter of internal case volume. Brass is quite a bit denser than powder and as such I suspect the effect on case volume is too small to factor.

Dan, I'm revisiting the old military vs. commercial argument.
That said, I'm not looking for benchrest accuracy, but prairie dog accuracy.
In my old age, I've tried to avoid trouble - where in my younger days, I invited it.

Ah, well it may influence accuracy, but I doubt pressure variations would be "significant".

This site got posted the other day in the Big Game rifles section of Handloading. Called Gordon's Reloading Tool. It is free software and basically does what Quick Load does.

https://grtools.de/doku.php

This gives you a way to change internal case capacities (as part of a whole lot of other stuff). If you want to see pressure curves dance around just try playing with case capacities.

I haven't used it a whole lot, but it seems like something everyone who reloads ought to at least try. You do need to create an account to download.

Funny, read the specs 1080p minimum resolution. 100M disk space. 1 Gig RAM minimum. No Win 11 so basically you have to have new laptop or desktop capable of running it. But no one is really making such a beast as Win 10 is dead in 3 years. So I guess nothing is free.

seems the military difference was around 10 grains heavier in 308 IIRC. FWIW

I think that could make a difference. At least it should on max loads.

Sort brass by weight when its important. I think I kept 223 stuff within one grain basically and all was well..

I look forward to M.D.'s answer on this. Years ago(1960 or so) I got my first lesson on this subject. I had been loading Winchester bass in 30.06 with IMR4895 and a 150-grain bullet with no problems. I tried the same load using military cases and got smoked primers and difficult extraction. Even as stupid as I was in those innocent days, I knew enough to stop shooting even though I wasn't sure what caused the problem.

I happen to use a Linux distribution, MX Linux. There are instructions for this. I've downloaded it to Windows 11, but have not tried it there yet.
EDIT
Just saw a notice from the website that the developer passed away at the end of January
Don't know about Windows 11. My installation went nuts after updating.

Where you might run into a problem with 11 is that it doesn’t offer any legacy support of traditional bios and instructions. UEFI only.

I would try adjusting the charge at least that much.

One of my early experiences with heavier brass occurred with the .257 Roberts. Have been loading for the 722 Remington inherited from my paternal grandmother for several years, using Winchester brass. Eventually worked up to a "modern pressure" load that got over 3200 fps from the 24" barrel using 100-grain Partitions.

Eventually decided I wanted to experiment with some other bullets, partly due to magazine assignments, so bought some more Winchester brass. Tried it with the 100-Partition load, and the first shot blew the primer. Had to tap the bolt handle open, and use pliers to pry the case out of the bolt face.

Turned out I'd missed one little thing about the headstamp: It said +P, so was designed for the new +P factory ammo. This was still comparatively mild, and the older Winchester brass would have handled it just fine. But apparently Winchester wanted to be very cautious, so made the +P stuff a LOT heavier.

That's when I started weighing every batch of brass I acquired, regardless of make.

I decided to weigh the 280 AI brass that I have lying around -- all clean -- all deprimed

Here's some figures:

280 AI made from 30-06 case LC
Number of cases 57
Average weight (mean) 194.14
minimum 189.5
maximum 199.3
variance 6.37906119561757
standard deviation 2.52568034311897

280AI from Peterson (mostly new a few once fired.)

Number of cases 49
Average weight (mean) 202.18
minimum 201.4
maximum 202.8
variance 0.558733690894112
standard deviation 0.747484910144754

280AI from Winchester 280 nickel plated brass

Number of cases 48
Average weight (mean) 187.46
minimum 184.4
maximum 191
variance 3.32984953703705
standard deviation 1.82478753202587

What alarmed me was the huge difference from the lightest to the heaviest, with the LC Brass -- 10 Grains! I'll be throwing some away.

A friend of mine in college once told me that free whiskey is the most expensive kind. I think that may be true of rifle brass too.

1.5 grains minimum reduction for 223/308 size cases if the brass is heavier than normal.

Easy after that, load and shoot one at a time until I get back to the speed I was at.

FC cases that have soft primer pockets in 223, take 1 grain less powder for same speed. IIRC they were 4 grains heavy on average.

Had kind of a similar experience decades ago, when my only big game rifle was a .30-06.

Discovered that heavier Remington brass required two grains less IMR4350 to get the same velocity/accuracy as Winchester brass with the 165-grain Nosler Solid Base. (I realize this dates me some, but there it is :-)

Guess I'll see about that tomorrow when I get my computer back from the doctor. GRT updates pretty frequently (nightly builds) so it may have been updated to work on W 11. We'll see about the full HD screen requirement too I suppose.

The Windows 10 going away in three years might not matter as the developer is now deceased. In three years it will either be totally dead or somebody will have picked it up.

Seems pretty useful, but I can't really vouch for how effective it might be. That sort of thing is above my pay grade. It is very close to what I looked at from my stuff.

A knowledgeable gentleman posted this in another discussion on another site.

"Keep in mind that 70:30 cartridge brass is 8.53 times denser than water, so you have to have 8.53 grains of brass weight difference to make 1 grain of water capacity difference, and that, in turn, will usually prove to take half a grain of powder to correct pressures to match, so you need over 17 grains difference in case weight for a grain of powder difference to make an exact match."

It should be obvious that this assumes the different brass is fully fireformed in a single chamber, such that the external dimensions are identical, and the weight difference can only reflect internal differences. And of course, both cases must be trimmed to the same length, and ideally have the same neck wall thickness so we're only talking internal volume reflected in their weights. But a thousandth or so difference in neck wall should be at the noise level anyway.

This would be an interesting ratio to test. I have some Hornady .35 Whelen brass that I have not yet used. Everything prior for that rifle has been Remington. The Hornady average 19 grains less than the Remington, so once they are fully fire formed, I'll have to see if those relationships hold.

Thoughts or comments on the quoted statement above?

Cheers,
Rex

In my experience the primary test is chronographing the same loads in two kinds of brass, as noted above. Computer predictions are pretty good these days, but still tend to rely most on so-called reality.

I have about 1000 pieces of 22-250 brass accumulated since I was a kid. Bought cheap loaded ammo routinely along with buying brass (you could buy it primed in those days) to shoot prairie dogs. All different headstamps. I didn’t know any better then; I just loaded them like a shotgun shell and went out to kill dogs.

The mixed headstamps shoot 1/2” in my gun with no issue. Must just be lucky or they are all more consistent that other chamberings

I'm wondering about the math...

I've been measuring weights on brass and have found a fairly large variance on brass weight even same manufacturer's brass. I think that many people will experience shooting a string and then a load will be way too hot. What do people blame this on? I doubt that they think of brass weight, and perhaps they should. I think that a difference of say ten grains on a brass case will make a considerable difference in pressure, velocity, POI, etc.

Match shooters, from what I've read, allow maybe .2 grains difference in brass weight. In my measurement of some LC brass I've seen 50 times that amount.

I know this summer; I will be weighing brass before I test loads. I won't be looking for .2 grains maximum, but I think maybe 2 grains maximum for hunting loads. I feel that I have been spinning my wheels trying to get sub minute of angle with large variations in brass. I don't often load maximum loads, so maybe that's the main reason I don't see one high pressure round in a string of shots..Further if the math shown above is true then why the large pressure differences in different manufacturer's brass?

I'll be using the .2 maximum for a couple of rifles that are paper punchers.

How consistent is the density of the metal used in rifle brass?

I would think probably within 1 to 2 percent, but I don't know that is what it is, especially using different brands that could be manufactured in different parts of the world. If the density of the metal can vary even 0.1 percent, brass that weighs on the order of 200 grains could have a 0.2 grain difference between two cases without any difference in internal volume,