Case Weight Consistency 308 win

[HK Dave]

Hey folks... just full length resized, trimmed to length, bevelled neck, deburred flash hole, cleaned primer hole on a few hundred FC 308 once fired brass pieces...

I just weighed them, and separated them into 175-176gr, 176-177gr, 177-178gr lots of 50.

Does this brass seem heavy to you? Weight wise, they are quite consistent. I was surprised. I guess the big dislike with this brass has to do with the softness or something?

BTW, anyone reload Prvi 308 brass?

I wish Lapua wasn't so stupidly expensive. Seems its gone up in price dramatically in the last 2 years. :P

[ExtremeX]

I load Prvi 308 brass and love it... Before I started loading it I was worried it was crap but it shoots great.



44gr Varget
168gr AMAX
CCI# 200
2.830 COAL IIRC

About 1/2 MOA @ 100 yards... Its a cherry picked group, but it averages closer to 3/4" MOA to 1 MOA without fail and I don't sort by weight.

I find the brass to be pretty good, I am only on its 3rd loading, but it seems to be holding up just fine.

[GeoffLinder]

A 3 grain case weight variance is pretty darned good for a 175 grain case. That's only a 1.7% total variance. I work with a 2 grain range allowance for my precision .223 cases and a 3 grain tolerance for my .270 cases after all metal removal has been done. I would think you are safe to consider them as one lot instead of three unless you are trying to make 1000 yard ammo.

I will bet that if you added neck shaving to the process they would be under 2 grain tolerance :-)

[Ike Arumba]

OP's weights are a little lower than the weights (~182 gr.) reported for Federal cases at http://www.700rifle.com/forums/viewtopic.php?id=908 , which also weighed Lapua (~177 gr.) and Winchester (~162 gr.).

[Raptor1Ronin]

I love My Prvi brass ! Stuff shoots great!

[FLIGHT762]

I'm using a good supply of once fired in bolt guns Federal GMM cases. These cases are recent Mfg. (the last couple of years) and have a blue lacquer primer sealant.

The fired cases weigh in between 181-184 grains (weighed with primer still in the case). They are very consistent. They reload well and last 6+ loadings in a bolt gun.

I do weigh them prior to any processing and cull out any cases heavier than 184 grains. I get only 1-2 cases out of 100 that will weigh a hair over 184Gr. For my purposes, the 3 grain variance works well.

Federal cases are softer than most other cases, but these newer cases are a little better than some older (10+year) lots. If you go too hot, you will stretch the primer pockets.

[damndave]

That is very little weight variance between cases. I honestly wouldn't even bother sorting them like that. I only sort by headstamp.

I have used all kinds of brass and they all seem pretty much the same to me.
PRVI, FC, CBC, PPU, LC Match, LC LR, Winchester, BH, PMC

[Exodus343]

Does brass weight affect accuracy?

[HK Dave]

A 3 grain case weight variance is pretty darned good for a 175 grain case. That's only a 1.7% total variance. I work with a 2 grain range allowance for my precision .223 cases and a 3 grain tolerance for my .270 cases after all metal removal has been done. I would think you are safe to consider them as one lot instead of three unless you are trying to make 1000 yard ammo.

I will bet that if you added neck shaving to the process they would be under 2 grain tolerance :-)

One lot it is... this is great! Over 300 cases within 3 grains of each other.

I believe the cases that run from 175-176 are the newer FGMM cases... whereas the others different FC cases from different loaded ammo.

Glad I sorted them... i found a few cases under 170gr and some over 180.

All the weights are without primer.

I'm using a good supply of once fired in bolt guns Federal GMM cases. These cases are recent Mfg. (the last couple of years) and have a blue lacquer primer sealant.

The fired cases weigh in between 181-184 grains (weighed with primer still in the case). They are very consistent. They reload well and last 6+ loadings in a bolt gun.

I do weigh them prior to any processing and cull out any cases heavier than 184 grains. I get only 1-2 cases out of 100 that will weigh a hair over 184Gr. For my purposes, the 3 grain variance works well.

Federal cases are softer than most other cases, but these newer cases are a little better than some older (10+year) lots. If you go too hot, you will stretch the primer pockets.

Some of this is the new FGMM cases with blue lacquer... some of it didn't have any lacquer... don't entirely recall where I got it but it's less than 5 years old... they all look and weigh the same... guess we'll see if the primer pockets loosen up.

I'm debating between 43.5gr or 44gr of Varget pushing 175 SMK with Rem 9 1/2 primers out of a 26" barrel. If I can get to 2700 fps with 43.5, I think I'll just do 43.5. Guess it's time to load and chrono.

[FLIGHT762]

Does brass weight affect accuracy?

In as much if you mix head stamps with varying weights of brass. A couple of months ago, I loaded up 10 test cases cases to test AR Comp using some 175 grain Nosler OTM's in my 308 bolt gun.

6 cases were Winchester cases that weighed in at 162 grains. 4 cases were "CBC 12" Military cases that weighed in at about 186 grains.

I shot them @ 100 yards in 2-5 round groups using a 1/2" grid target. The 6 Winchester cased loads landed into a .63" group. The 4- "CBC 12" cases landed into a .70" group that impacted 1" lower than the Winchester brass group.

The load was accurate, but showed a point of impact change with the heavier brass.

Had I shot all 10 shots into one group, the group would have opened up to 1.3" due to the large difference in the case weights.

[HK Dave]

The pressure change in the case difference caused quite the shift. Thanks for telling us about it. Glad to see a real world example.

[FLIGHT762]

I've also had similar P.O.I. shifts by just changing to a different primer.

[Ahhnother8]

If you shoot crappy bullets through a crappy bore, it simply does not matter. Or if you are "plinking", it does not matter. Conversely, if you want to shoot tiny little groups, EVERYTHING matters.

[HK Dave]

Everything matters.

[GeoffLinder]

The pressure change in the case difference caused quite the shift. Thanks for telling us about it. Glad to see a real world example.

Hard to say the case volume pressure difference did this. Changing anything can create a POI change. Different neck thickness causing release tension difference, different resonance in barrel.

IMHO, 100 yards is too short of a distance to see vertical stringing differences from a pressure change if it is not a huge change. I would like to hear what the velocity difference is from this example before I would draw that conclusion.

Generally, some pressure variance only will not exhibit much measurable vertical stringing until 250-300 yards plus IME. A 1" vertical difference at 100 yards would require a fairly significant velocity difference generally if it is caused entirely by pressure.