not sure how to work it out mathematically...

quote:

Originally posted by Trax:
Not sure how to work it out mathematically...

Not sure you're going to. Much easier to re-size and then measure.

BTW, where are you getting the donor brass? The 300H&H stuff is hard to find.
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You do it mathematically by using trigonometry. Does anyone remember that from high school? My little drawing with calculations show the neck would get shorter by about .130". The basic 300 H&H case has a neck length of .371" with the case at maximum length. The difference between the two is .241" That is the new neck length.

Thanks, I felt too lazy to do the trig. myself
Looks very much like a 2:1 reduction rate, but .241" is too short for my liking.
... but 7mm/300H&H would be ok, a rough calc. in my mind tells it would have very near a .284" neck

quote:

Originally posted by Winchester 69:
BTW, where are you getting the donor brass? The 300H&H stuff is hard to find.
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BrassWorld had some the other day, but looking now its all gone!

Why was I thinking that reducing the neck diameter would increase the length of the neck, not to mention increasing neck wall thickness?

Excuse me. I have to get back to my calculations.
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If you keep the shoulder angle the same the length of the neck is taken up in the longer shoulder - that leaves a shorter neck. If you don't like the new length then increase the angle of the shoulder and make the neck fit your needs.