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Cartridge Case Weight
Ambrose
Member Posts: 3,208 ✭✭✭✭
Getting ready to load for a recent new-to-me .270. I have a pretty good supply of brass of several brands so in the process of picking a brand, I thought I'd weigh 'em.
Sako 181 gr.
nickle Win 187 gr.
Win 188 gr.
PPU 188 gr.
RP 196 gr.
FC 200 gr.
Quite a spread! I guess I'll try a conservative load with a box loaded with Sako cases and a box with Federal cases and see what the difference is. Of course the proper way to check case capacity is to fill to the base of the neck with water and weigh that. But that's messy.
Comments
Are you going to sort each brand by weight also?
I reload and work up reloads for maximum accuracy in Bolt action rifles that I have glass bedded.
I weigh the brass I'm going to reload and for the 30-06, 270 area of caliber rifles I have the brass separated into a tolerance of not over 4 grains difference in weight. The name on the brass (manufacturer of the brass) is not as important as keeping the weight within a tolerance.
I can tell you this from experience.
If I took your 181 gr Sako brass and your Fed 200 grain brass and loaded each brass with the same exact recipe and shot them at the same target in a very accurate rifle that is capable of one inch or better groups, the groups would most likely spread to as much as 3 inches.
I've proven this to others who just done a jaw dropper when they seen such.
Summary: What I'm saying is you might take the 181 gr Brass and shoot a one inch or less group, then take the 200 gr FC brass and shoot a 1 inch group but they will usually impact at a different place on the target, sometimes as much as 3 inch apart. (the heavier weight brass usually has less space/volume inside)
Just mixing up brass and ignoring the weight of the brass will quite often make a very accurate rifle look very bad accuracy wise.
One reason for such is the heavier brass usually has less space inside as compared to the lighter weight brass and with the same powder charge the pressure may be higher in the brass with less volume. In same category as varying the powder charge up and down and expecting the accuracy to remain same. I've found that max accuracy usually results from being consistent and mixing weight of brass by several grains difference in weight is one of the factors that will usually result in poor consistent accuracy and is more important than selecting brass all made by the same manufacturer. If I select same weight range of brass when reloading I and the gun usually ignore who made the brass for consistent accuracy.
Heavier brass will usually mean less case volume as stated and can lead to higher pressures.
Max loads could be a kaboom.
Oak, what else do you weigh beside bras?
Someone had to ask.
Generally, you don't need to weigh them, you can judge them by the size.........
and feel
I would've thought capacity would be more important in shells than weight. I would like to know what the water difference between say the Sako and FC.
Heavier shell casing have less capacity, powder or water. So weight affects capacity.
Get 2 different brands of shell casings of same cartridge and fill them with water. Weigh the water required to fill each one , you questions answered
Well, it's been a while but I finally got around to it. Got a different new-to-me rifle at a local live auction since I first posted; Ruger Hawkeye, serial # dates it to 2014. Set it up with an old Lyman AA 6X. Loaded 20 rounds with the old "standard" load of 60 grs. of H4831, 130 gr Sierra spitzer, WLR primer, 10 Sako & 10 FC.
Two 5-shot groups averaged 2963 fps with Sako brass & 3034 fps with FC.
Loaded another 20 with 55/H4350, same bullet & primer and 1/2 & 1/2 cases.
The groups ave. 3018 with Sako & 3073 with FC.
The FC groups were about 1/2" higher and slightly left of the Sakos.
I guess the next order of business will be to put up a batch with one each of Sako, Win, PPU, RP, & FC brass and see what the groups are like. Stay tuned if you're interested.
'
If you weigh the Sako and FC I wager the FC will be heavier.
Very interesting post. I'll keep watching for updates.
You say: The FC groups were about 1/2" higher and slightly left of the Sakos.
This is one of the points I was indicating in my above post about accuracy results when shooting mixed WEIGHT brass from a very accurate rifle. Not paying attention to brass WEIGHT can make a normally very accurate rifle produce erratic groups when shooting mixed weight brass. I keep my rifle brass labeled by weight when testing for a accuracy reload. (the WEIGHT is usually more important than who's name is one the brass)I've also found that severe burrs INSIDE the the hulls primer pocket can cause flyers. (Lyman and others makes a primer pocket uniformer for deburring/chamfering the primer pockets inside the cases.
I also do not bother using a chronograph at first when bench testing for a accuracy load.
I let the rifle tell me what reloading recipe it wants for accuracy, then use the chronograph later mainly just to check the velocity.
I do not need to know the chrony's standard deviation shot to shot as long as the gun is producing consistent accuracy results.