Brass Weight Variations

NorthernCX

NorthernCX

CGN Regular
Rating - 100%
30   0   0
Location
In My House
OK, finally got a digital jeweler's scale to start weighing brass... and lo and behold, even my beloved nickel-plated Winchester brass showed 3 distinct weight groups out of a box of 20! As much as 9 grains difference!

How picky should I be? I've struggled with that rifle, as it was a Savage pkg deal that I a) shot the rings loose, b)then shot the bases loose and c) also shot the front action screw loose. In the process of straightening all that out, I dropped the cheapo scope, bending the bell housing. So on went a Bushnell Elite 3200. Things are better but as they should be. The last rounds I sent downrange showed a velocity spread of 20 fps, with unweighed brass, but couldn't make more than a 3-inch group at 100 yards.

Should I keep the brass sorted (and any others, I've got lots) in this manner? Group it together based on an average weight +/- 2 grains? Or what other number should be suitable?
 
3 inches @ 100 yards is too large a group that your brass would be the culprit. Are you sure the scope is mounted solidly? The velocity spread of 20fps shouldn't really make a difference at 100 yards.

What caliber is this. 9 grains is a lot. My worst winchester brass has been +/- 5gr on average.

How are you measuring your charges? Are you loading them really really hot? Perhaps past the point of better accuracy?
 
I started weighing brass over 40 years ago. In one box of Dominion .30-06 the variation was 17 grains. The second box was 23 grains. I got one box out of that with 10 grains variation. I weighed 2 boxes of Norma 6mm Remington. The first box varied 1.1 grains and the second (0.8 grains) fit within the previous box.

I have also weighed factory powder charges, and found a max variation of 2.1 grains with some Winchester .308 - 150 grain loadings. No one would load with that much variation.

Recent sampling of brass might find one that is either extremely high or low from the average but I take little exception to a 2 grain variation.

On a recent purchase of 100 .25-06, there is one lot or 45, another of 35 then 5 that were high and 14 that were low. I simply set the scale and as long as the beam stays inside the max and min that become one lot and is essentially a 2 grain variation.
 
Well, the caliber is 30-06, and I didn't think the large groups were solely because of the brass weight (one reason why I wasn't weighing brass before). I'm trying to eliminate every possible variable.

The scope is on solid, hasn't moved. I've just picked up a Wheeler scope level, going to double-check that. I haven't been running hot loads; maybe I just haven't found the best combo for the rifle- I don't know.

I will definitely be sorting my brass into groups with a 2-gr. spread; most of the load data I have shows load ranges of less than 9 grains and I don't fancy wrecking my rifle or, worse yet, damaging my already aesthetically-challenged mug ;)

Also going to borrow a torque wrench and make sure the action screws are at 65 in-lbs.

Can't think of anything else to do but get out and shoot it, find a load it likes and make sure I'm doing my part... but considering my qualifying scores for work with iron sights, maybe I'm just one of those guys that don't do well with a scope....
 
Case weight won't matter. The bullet and load do. Your rifle just doesn't like whatever load you're using. Try some 165 grain hunting bullets with IMR4064, IMR or H 4895(close but not the same) or Varget.
 
I've been using Varget, and have a can of H4895. So far I've gone through Nosler BTs, Accubonds and Partitions (it does seem to have a liking for BTs, but I won't use them for hunting since the last deer I shot with one), all in the 150-168 grain range, Barnes XLC in 165 (it loved those, but ran out before I put the new scope on) but they aren't made anymore, Hornady IB in 110, 165 and 180 grain.

Strangely enough, the 110s and 180s have given me the 'best' groups of 3 inches. There's gotta be something else.

I'm not sure how 9 grains difference isn't going to affect pressure though if the bullet and powder charges are the same... please someone explain!
 
NorthernCX said:
Well, the caliber is 30-06, and I didn't think the large groups were solely because of the brass weight (one reason why I wasn't weighing brass before). I'm trying to eliminate every possible variable.

The scope is on solid, hasn't moved. I've just picked up a Wheeler scope level, going to double-check that. I haven't been running hot loads; maybe I just haven't found the best combo for the rifle- I don't know.

I will definitely be sorting my brass into groups with a 2-gr. spread; most of the load data I have shows load ranges of less than 9 grains and I don't fancy wrecking my rifle or, worse yet, damaging my already aesthetically-challenged mug ;)

Also going to borrow a torque wrench and make sure the action screws are at 65 in-lbs.

Can't think of anything else to do but get out and shoot it, find a load it likes and make sure I'm doing my part... but considering my qualifying scores for work with iron sights, maybe I'm just one of those guys that don't do well with a scope....
Click to expand...

Get a proven shooter to shoot it for you... my rifle's groups always improve when I put someone who doesn't flinch behind the butt.
 
aletheuo said:
Get a proven shooter to shoot it for you... my rifle's groups always improve when I put someone who doesn't flinch behind the butt.
Click to expand...

I don't flinch- I started to after 20 rounds with the stock recoil pad when it was new- it's a light plastic stock and came with 1/2 inch of tractor tire rubber for a pad. So I put a Limbsaver on it and now will go to the range and put 50-75 down the pipe and love every one. It might be me, though, like I said earlier, maybe I don't take well to shooting through optics... I'm going to load some and get out this weekend- hunting season's coming soon!
 
NorthernCX said:
I'm not sure how 9 grains difference isn't going to affect pressure though if the bullet and powder charges are the same... please someone explain!
Click to expand...

i don't shoot rifle and haven't yet reloaded, but look at the basics - the case doesn't really move during firing so weight is a non-factor. it's "stuck" with the barrel which weighs hundreds (if not thousands) of grains, so really a small weight diff in the brass is squat. and it doesn't move until way late into the projectile projecting force. if you got a bolt action, i don't move for a long time, and in a semi-auto it tends not to go anywhere until chamber pressure is low - low enough that it doesn't affect the bullet anymore anyways.
 
BP7, I think you've misunderstood the issue. I'm not talking about adding to the weight of the rifle or the cartridge itself. From Modern Reloading, Second Edition:

A 165-gr. jacketed bullet has a starting load of H4350 of 53gr. and a maximum, NEVER EXCEED load of 59gr. That maximum load has a listed pressure of 59,280 psi. 6 grains of difference between starting load and maximum load. It's not the weight per se, it's where the weight comes from. If both cartridges are from the same manufacturer and have been shot from my rifle, and trimmed to the same length, the outside dimensions are (or should be) identical.

Now if those same 2 cases vary in weight by 9 grains, then (it seems to me, and if I understand this correctly) that means the heavier case has more metal, hence less internal VOLUME. It's that volume that increases the pressure, and, if I'm still following this correctly, if I put the SAME maximum powder charge in those 2 cases, the heavier case would be the same as a 2-grain overcharge, POTENTIALLY increasing max pressure beyond what is safe. At the very least, it would likely affect accuracy.

At least, that's how I've interpreted what I've read, and why I've asked how much variation is too much. All things considered, it's looking like I'll sort my brass into groups with a 2-grain variation just to be on the safe side.

Experienced reloaders, do I have this right, or am I being too paranoid?:runaway:
 
it's not so much case weight that should be sorted but case capacity.

When measuring the water capacity (volume) of a case, it's better to use a fired case before it is resized, since this is closer to the size of the case expanded at firing. A little dishwashing soap lets the water lie flat across the case mouth, improving the accuracy of the measurement. I find it simplest to first weigh the dry case, fill it with water, and then dump the water and case into the scale's pan.

Cases can vary greatly in weight among makers. In general, modern cases are slightly thicker and heavier than older ones for the same cartridge. Heavier cases will have less capacity, with every 8.5 gn of brass displacing about 1 gn of water capacity. In small cases such as the .22 Hornet, differences of up to 10% can be found, but variations of 2 gn of water is more typical for cases of the size of the .30 Springfield.
Click to expand...

And as it's already been pointed out, 20fps spread at 100yd, you're not likely looking at the right problem if you can't go under 3''. Look into your bench technique, good torque on base and rings, cheap scope that gave up to the 30-06 etc.
 
in a typical case, there's more metal in the head area than anywhere else, and for 9 grains of weight, how much extra metal (in cc) would that use up from your available internal volume?

1 grain = 65mg, so 9 grains = 585mg, and for brass that equates to around...

brass = 8.5grams per cc, so 585mg / 8.5g/cc = 0.07cc

thus, your weight difference accounts for 0.07cc of volume
30-06 capacity is around 4.4cc

you're humming-h-hawing over 0.07 / 4.4 = 1.6% of internal volume being "lost"

by the way, as the bullet "slowly" makes its way out of the case, the "internal volume" grows to include the part of the barrel that's already behind the bullet. so the 1.6% loss is only up until the bullet gets physically separated from the case neck - after that, the difference vanishes into nothingness
 
is it a heavy barrel or light weight "alaskan" type barrel. if light weight over heating opens up groups, are you cleaning with a "jag" if so through a bore brush down the pipe for a good cleaning, are you using a solvent that eliminates copper? lastly check the crown could be nicked or worse dented? so many things affect accuracy its just hard to say, just start eliminating everything, consistant charges of powder, OAL, bullets, powder, wow the list goes on. can you borrow a steady rest and shoot some factory GMM to get yourself a bench mark. yes case capacity does effect pressure thats why it is said with military brass to start on the low side working up till you see over pressure then back off. a friends savage medium contour barrel heats up after 5 quick succession shots and his groups suffer greatly, put some time in between shots maybe this will help.
 
Yes I agree that the case weight at this point is not a factor. Your rifle does not like one of the components, powder (weight or recipie), bullet (weight or brand), primer. I do not use sierra, hornady, or my own cast paperpatch bullets. Firstly I am too cheap to pay for those overly expensive bullets, and I do not need to, my regular old bullets work just fine and drops any deer I've ever shot with no problems within a few feet of being shot. As well the rifle has some issue. Savage makes an excellent rifle, definitly capable of more than 3" at 100. Maybe the crown has an issue. Also are you full lnegth sizing your brass or only neck sizing??? Try just neck sizing for a few rounds just to see if it makes a difference. Just remember only change one variable at a time. Best of luck. Matt
 
OK, I think I better understand how much the weight of the brass does/doesn't affect things. Guess I'm going to start with some VERY careful loads and slowly compare.

Yes, it's a relatively light barrel and does get warm, even from a good sunny day. I've seen heat shimmer even at 3X after 4 rounds. More time between shots is definitely in order. The crown is clean; I baby my rifles.

No, I'm not cleaning between individual shots... with the break-in I did on it, there's no obvious fouling after 20 shots (but I know it's there, I'm only saying the bore is broken in and doesn't pick up too much gunk). Range cleaning after 10-20 rounds with a Boresnake. Cleaning at home after is Hoppes 9, Hoppes Copper solvent, bore mop, bore brush, jags/patches (I don't reuse patches) -don't have that in specific order, BTW until the patches come out clean.

Neck sizing only on brass I've saved from factory loads shot by myself. I'm trying to eliminate every possible thing. OAL is determined mainly by my rifle. For each bullet type I've tried I've loaded a bullet seated long into an empty, once-fired and unprimed case, gently chambered it so the rifling seats the bullet, taken it out and set the bullet back another couple 'thou', then used a Lee Factory Crimp Die to set it there as a dummy for future reloads with the same bullet shape- I set that dummy into the shell holder, run it up and set the seating die to just touch that particular bullet.

Trying to be as consistent as possible; I'm just going to have to steady down more and take more time between shots, and find out what it likes. I've put together good groups in the past; I can't figure out what's changed- but it looks like brass is the least of my worries.
 
Firstly, 9 grains difference in the weight of the brass makes a difference of powder capacity of far less than two grains.
No matter what you do, every bullet fired will not be at the same velocity. If the variance is 20 to 25 fps for a sporting rifle, that is darn good and I doubt if using brass mixed up with a 9 grain variance, high to low, would increase the natural variance from bullet to bullet.
Secondly, 59 grains of 4350 (either variety) with a 165 grain bullet has not been a heavy load in the 30-06 rifles I have used it in.
Thirdly, when the manual states, "Maximum," load, it does not mean it is loaded to the point where any more powder would "blow the gun up in your face." What that word maximum means is that it is what the SAAMI, the organization that governs all the dimensions and pressures, for example, for all sporting guns in north america, has deemed the working pressure for that cartridge. That is also the same pressure they have deemed that factory ammunition can be loaded to. So, the maximum load they give will be about the same pressure as a factory loaded cartridge.
Fourthly, whenever a rifle does not shoot as well as it is expected it should, the very first consideration should be to the bedding of the rifle. Whenever accuracy of a rifle is talked about, everybody and his second cousin will spout out to tighten the guard screws. Well, I will let you in on a little secret. If the action does not properly fit the stock, tightening the guard screws can easily put strain and twist on the action and make the rifle shoot worse, than it would if the srews were eased off!
The bottom line, have the action and barrel properly bedded.
 
Something you might want to try, loosen the action screws and pull the action back into the stock and holding the rifle muzzle up tighten the action screws in increments till you get to about 40 in-lbs. The reason for this is in some factory stocks there is enough slop in the recoil lug area to have minimal contact between the lug and the stock when the screws are tightened with the action resting forward , pulling the action into the stock forces better contact between the lug and stock. It only takes a few seconds and might solve your problem. good luck.
 
Thanks all, I'll definitely check out the bedding... better call my buddy for his torque wrench...

The rifle's pillar bedded in a synthetic stock... would glassing it make that much difference?
 
You must log in or register to reply here.
Back
Top Bottom