7 BR Brass made from 6 BR

[gzig5]

I'm looking at making 7BR from 6BR considering the Rem 7BR brass is drying up. Want to build my kid a 7BR on a Mini Mauser. Main concern is neck length of the resulting neck up operation. I'd expect they end up shorter, and if so about how much? Longer or thicker is fine as I can trim or turn. 10-20 thou wouldn't be a problem, but more than that I worry about fouling build up in front of the neck in the chamber and/or potential erosion? I know you can fire short neck cases but my understanding is that it could lead to issues down the road. Don't care to debate that, just wondering how the neck length turns out.

 

[TC260]

My notes are all packed away after a move so don't recall the case lengths. I was necking up Lapua brass for an MOA pistol and had to remove donuts but that chamber was snug IIRC.

 

[Terry]

I have 7Br brass.

 

[gzig5]

I have brass to get started as well, but it won't last forever. Thus the question.