Freebore in the RUM family

[hemiford]

Does anyone know how much freebore Remington puts into their
RUM barrels ? I think I read .400 on the 7mm and the 300, but I
don't know about the 338 or 375. I would think it would be different.

I'm considering ordering a 375 barrel.

I think I have a handle on how freebore potentially affects both accuracy
and safety (overpressure), and the safety consideration concerns me more.

When SAMMI specs a chamber, does it include a freebore spec ?

Or is freebore a custom variable that must be reamed in specially ?

I must learn how to order the barrel properly.

 

[Edd]

The SAAMI specs include freebore but you can order a reamer with whatever freebore you want.

SAAMI specs

7mm RUM .400"
300 RUM .110"
338 RUM .160"
375 RUM .175"

 

[hemiford]

Wow. Thank you Edd.
I do not understand the pattern there at all. There must be some rationale.

 

[Edd]

There must be some rationale.

Don't confuse yourself with logic. I've done a lot of research on free bore. I don't think it is a precise number that is chosen by some sophisticated scientific calculation.

 

[hemiford]

OK. I still like to look for patterns, perhaps I could write you a long boring PM
and see if it makes any sense. I have a feeling freebore involves the maximum
grainweight bullet like that is most likely to be fired.

By chance, do you know the freebore for 7stw ?

 

[Edd]

By chance, do you know the freebore for 7stw ?

.200"