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300 Win Mag Obermeyer chamber - Anybody have info on this?

RHunter

Sergeant
Banned !
Full Member
Sep 2, 2013
857
7
Florida
Just about to build a new 300 Win Mag. I see PTG has a "300 Win Mag Obermeyer" reamer. Anybody have any info on this variant? Throat length? Maybe even the print?
 
.3085 freebore diameter. I can send you a print.
 
That would be great, I'd like to see it and upload it to the thread for others in the future that may be interested in this chamber.

Any information as to "why" this profile was designed would be helpful. Benefits, reasoning behind it, was it developed for a specific bullet??
 
That would be great, I'd like to see it and upload it to the thread for others in the future that may be interested in this chamber.

Any information as to "why" this profile was designed would be helpful. Benefits, reasoning behind it, was it developed for a specific bullet??

Isn't it when Boots switched from tight bore they figured out that a little bit over diameter was actually shooting better?
I think he mentioned something about it when I ordered a .30 cal (with the intent of .300WM) from him earlier this year.
 
Isn't it when Boots switched from tight bore they figured out that a little bit over diameter was actually shooting better?

I have no knowledge of the history behind it, I was hoping to catch someone on here that knows the skinny behind the reason for the design.
 
I have no knowledge of the history behind it, I was hoping to catch someone on here that knows the skinny behind the reason for the design.

I wanna say he was building them loose for cast bullets, or something, but they shot slightly better than some standard .300 WM chambers. I can't remember.
 
I wanna say he was building them loose for cast bullets, or something, but they shot slightly better than some standard .300 WM chambers. I can't remember.

Why would anyone shoot cast bullets in a Win Mag?
 
Why would anyone shoot cast bullets in a Win Mag?

Yeah I would think the velocity would cause the chamber to get lead lined...

I tried shooting cast out of my old Garand and getting them slow enough to get a good grab in the rifling and where you had any decent accuracy and still have the rifle cycle was a challenge. About the only thing I have found that shoots 30 cal cast worth a shit is shooting cast bullets subsonic out of a 300 Blackout...

Brutas was kind enough to send me the .pdf print for that Obermeyer design, super short throat. I converted it to a .jpg to upload it so all can see what it is.

300 win obermeyer.jpg

I am not sure what bullet this was designed for but whatever it was it's ogive is awfully close to the end of the neck... You'd have to seat them deep to keep them off the lands.