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This question relates to a new batch of .308 Norma Magnum brass. My previous batches have varied 220-223 grains (virgin unfired unprimed) but the latest batch varies 220-225 grains.
Q: Is this variance likely to significantly affect pressures and grouping with my existing load?
(180gn sgk/cci250 / IMR4831 / 70.7 gn = 2900 fps / < .75moa grp)
Note: This cartridge is very similar to 300Win mag.
Greetings Woody,Quote:
Originally Posted by Woody
That is still very consistent brass. I doubt if you would notice any difference. It is not the weight of the cases that creates the difference but the capacity of which weight is but one indicator. It is likely that the variation would be swamped by other variables. Congratulations on keeping a fine old cartridge alive.
Regards Grandpamac.
Weighing cases doesn't tell you too much because the correlation between heavier cases and having less internal case volume is a bit loose. Depending on where the extra material is on the case, a heavier one might still have the same volume as a lighter one. Same volume = same pressure = same speed.
So it's difficult to answer your question with any amount of certainty. I'd expect your ES and SD to go up if the capacities are all over the place (which more variance in weight suggests they might have) and that won't help your groups at longer range, but your load sounds very sane so no issues with safety, and under 300m I can't see it having any noticeable effect.
Best way to find out will be to put some over the chrono.
The Speer no 9 Manual lists 71 grains of IMR4831 behind their 180 grain spitzer for 3,017 fps. They were using Norma cases in a Sako with a 24.5 inch barrel. Interestingly they used CCI200 primers in that load. They did use CCI250 primers with the ball powders however.
Grandpamac.
Thanks chaps. About what I think too. When I use up my earlier brass I will run a tight ladder as a check with the new. I also have some brass in norma reload original boxes from 1965 and it is very consistent around 221 grains, so in general Norma is very consistent with this calibre.
As an aside; with 7*61 brass I found three distinct changes during there evolution from 7*61 sharpe and hart through to the latest 7*61 super, the originals being much heavier and suited to the older IMR4350 that sharpe developed the cartridge around. Sold that rifle recently and it would still shoot x's consistently at 600. Thanks again for your input.
Greetings,
If by reloads you mean Norma cases with RE on the head stamp the RE stands for Reloadable not reloads. Norma removed the RE when the Americans thought it meant reloaded. The Sharpe and Hart case was re designed internally to give additional capacity and was given the Super name at that time. Another great cartridge you used to see much more.
Grandpamac.
7x61 is still a fine cartridge and reminds me that I need to get my old 65 DL Shultz and Larsen out for a few shots.
Really accurate and easy to load cartridge.
I cut my reloading teeth on Norma 308W Re brass. I believe the other story around the Re is that it was to indicate the case was Boxer not Berdan primed ie "easily" reloadable. Obviously Berdan brass is still reloadable just far more difficult. The Re may have started out for the growing American market and then later removed. The only flaw is that, and I cannot remember clearly that far back, factory loaded Norma (Boxer) may not have been stamped Re. Need someone with a finer memory than mine to recall.Quote:
Originally Posted by grandpamac
Interestingly this is what a Swedish contributor over at the other pub said in a thread back in 2014.
Regarding the Norma "Re"; Norma added "Re" to the headstamp (reloadable/rechargable) there was a token system where you got paid for returning brass to Norma (if you didnīt reload them yourself)