300 Win Mag to 300 RUM question

[GNERGY]

My friend has a Montana rifle in 300 Win mag and wants me to rechamber it to 300 Ultra mag. I am not sure if I have to do anything with the feed lips in the action, or will the rum feed because the rum is the same OD of the belt on the win mag. Any of you gentlemen had to deal with this.
Thanks in advance.
Tarey

 

[46and2]

If his action is a Rem 700 compatible platform he can/should het a Wyatt's extended mag box, he'll have to modify the bolt stop, pretty easy.
But yes, the bolt face is the same diameter.

 

[Adam in WI]

OP's questioning a Montana... In other words, Model 70 pattern. You might consider calling MRC and asking if there's a difference in the feed lips.

 

[Stan Taylor]

The primary question I have is how many rounds on this 300 win mag you are chambering.

 

[GNERGY]

Stan,
less then 100.
Tried calling Montana rifles and their recording says they will be back open on Feb. 15 ???
Tarey

 

[Stan Taylor]

I don't like sticking a reamer in a used barrel but a hundred rounds you may be safe.