New Brass W/Neck Size Die

[alamogunr]

The experimenters here should be able to answer this. I bought a set of Neck Size 303 British dies from a member here. I have a small supply of new brass(never fired). Should I fire form this brass before sizing and loading or is it OK to just neck size and load.

[mpmarty]

I'd just neck size and load.

[runfiverun]

i like to get them in the gun before i start whittling on them.
nothing worse than trimming a whole batch of brass only to have it shrink when fired,
except a brand new case that won't chamber.
definatly a neck sizing at minimum.

[Quigley284]

You can never be sure how new brass in going to go through your new rifle until it's been fired once. Mike

[RobsTV]

Fireform new .303 brit brass with rubber o-ring (http://castboolits.gunloads.com/showthread.php?t=135910), then neck size after that.

[alamogunr]

Fireform new .303 brit brass with rubber o-ring (http://castboolits.gunloads.com/showthread.php?t=135910), then neck size after that.

That is a new one on me(not that a lot of things aren't). I'll have to open one of the bags and take a case to the parts store and get some O-rings.

Is this done because .303 dies set the shoulder back when normally sized?

[Gtek]

It will hold case against bolt face first firing and allow case to grow to max chamber dimension. Perfect headspace- you are sizing the case to YOUR chamber. Then trim and neck, makes them last longer. And take more than one o-ring. Gtek

[williamwaco]

Never heard of that O ring trick but it seems plausible.

I usually size the neck only on new brass just to insure it is round, then load plinkers and shoot them. Doesn't matter what the actual load is.

You didn't ask about trimming but as already mentioned, do not trim before fire forming.


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