300 Wby to 340 wby

[DOUGLAS D]

Anyone built 340 Brass out of 300 Wby?
Should be doable but which is best?
Fire form or neck up?

 

[reb]

I would neck up to. 338 then fire form

 

[dan belisle]

All my early 340 brass was made from Win 375 H&H brass. Neck down and fire form. 300 Wby should work fine, just neck it up. - dan

 

[Falconflyer]

It would be difficult to fireform before necking up.

 

[medvedqc]

All my early 340 brass was made from Win 375 H&H brass. Neck down and fire form. 300 Wby should work fine, just neck it up. - dan

i did the same when i had my 340 one too. and i will suggest the same.

 

[DOUGLAS D]

Thanks for the info guys.
The 340 is one I sold to a friend and kept the 300.
I’ll take your advice but also bring the actual rifle back so I can check for function with the reformed brass.
Not too concerned with the head stamp being wrong as I don’t think a 340 will chamber in a 300 if the situation ever arouse.