300 norma mag

[Mr V]

Im building Norma 300 mag,alredy have Stiller action 338 lapua mag .Im going to instal this in MDT chassis with 3.85 magazine.Also will use norma brass for reloading and otm berrgers 230.The gunsmith is asking me to biuld 3-4 rounds so he can drill the barrel.
My question is,
Can I extend the COAL from base to tip as much as posibe.I other words can I billd a round from tip to base at 3.75 or more or what is your take going to be?Thank you so much!

 

[Supersubes]

Depends on your bullet choice a bit, but I don’t think you’ll be using all that mag length the norma is a lot shorter than the Lapua mag.

I throated my barrel to .250 freebore, and my ammo is right around 3.57 with a 208 or 225 ELD.

Build a round using your longest bullet so the bottom of the bearing surface is .050”-.075 or so above the neck shoulder junction of the case. I don’t believe seating it abnormally long will get you any additional performance. I tested that by throating mine longer, and it did virtually nothing.

 

[Mr V]

Thank you!

 

[Simia Dei]

My old norma was chambered using the SAAMI spec reamer and from memory it was loading to 3.650” with a 0.02” jump using the 230 Berger. I’d have to check my notes though. From a 28 inch barrel I saw 2950fps using retumbo, but I never shot it enough to see the barrel speed up before I moved it along. You might not need to extend the COAL too much to get decent results, plus you’ll get more rounds out our your barrel.

 

[WeiserBucks]

Forget about Norma brass and use Peterson until Lapua hits the shelves. Thank me later .