Winchester brass to Norma brass

jerrya

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i have been loading 270 wsm Winchester brass but picked up 50 new Norma brass for my 270 wsm. I tried comparing capacities last night just filling one of each type to the bottom of the neck with the powder I use. I was quite surprised to see the Winchester held about 3.8 grains more powder. I know this measurement is not exact here but would that 3.8 grains of powder difference be close proportionally to where my maximum load would be? 67.5 grains of r26 was my maximum charge where I hit max speed but never had pressure signs on the brass so would it be around 64 gains for the Norma?
 
Thanks guys. I also used table salt when measuring. I am going to fireform them and then compare. Then I can proceed with the load development again and possibly start off lower as Rifledude explained.
 
Usually use water to compare volumes accurately. And be careful when loading maximum. Pressure is not proportional to charge weight and can "turn a corner" and take a big jump when you don't expect one.
 
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While I find Norma brass to be very nice to work with, some lots, particularly in some chamberings, tend to be on the "soft" side.
Therefore, it is always prudent to start lower and work up carefully.
I have one lot of 6.5x55 brass, that will only tolerate a charge 4 grains below the safe charge in a Winchester case
before pressure signs show up. D.
 
If I had to guess I'd say that you will end up with 1 grain less powder in the Norma brass for the same velocity. At least that's what usually happens to me on similar switches.A chronograph is a handy thing.

Often when I hear about soft Norma brass its just that the loader used the same charges and found that the Norma got loose pockets faster. The reality was that the loads were too hot in the heavier brass. Loaded right that stuff is seriously tough.
 
At least you asked first ,which is more than some do.As the guys commented prior, work the load up from scratch and you'll be fine..........Harold
 
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