Rebarrel and Rechamber Question

[Lahunter76]

i have a Mark V in Weatherby 300. I called and asked a gunsmith if he could rechamber/rebarrel my current action to a 300 Norma Mag. I understand that it's a different rim diameter, but didn't think it was not possible....the gunsmith said that it couldn't be done due to something about how the extractor is done on the Mark Vs.....I did not feel this is accurate, but I admit I am very green to all this.....am I mistaken, but if not how do I go about making the swap? I hope I am even asking the correct questions lol

 

[MontanaRifleman]

I'm not a gunsmith but off the top of my head jumping from a 300 Wby bolt face to a 300 Norma bolt face is a big jump, sooo, it sounds like there could be an extractor issue. (oh, BTW, you would probably get more good advice in the gun smithing forum for this subject) Anyway, the 30-378 rim is only 6 thou smaller than the 300 Norma, so should be an easy mod, if they are both 9 lugs which I believe they are. So you would need to find a 30-378 , 378 or one of the larger rimmed Wby mags bolt to replace your current bolt. Which brings me to another subject. 9 lugs

I had a chat with a very well known and respected gunsmith who used to post in these forums, about using a Mark V action for a build. He told me he didn't like the Mark V actions because of the 9 lugs, because it was pretty much impossible to get all the lugs lapped so they were all engaging when locked, resulting in an uneven situation. Now this gunsmith used to work for another gunsmith, before he went out on his own. Gunsmith #2 did a 300 RUM (Rem 700) build for me and that thing was a tack driver. .2 MOA @ 427 yards. So it turns out that Mark V actions were GS #2's favorite factory actions to work on. Go figure.

So, options that I can see...

Pick another cartridge like a 300 RUM or 30 Nosler, which is right between the 300 Wby and the RUM

Find a the larger faced bolt, if it would even fit

Buy a custom action

Options 1 and 2 are going to be a lot more complicated (COAL, blue printing, etc) and probably as costly as option 3

Maybe JE Custom will jump in with some wisdom. He knows a whole lot more than I do about the subject

 

[Lahunter76]

After a lot of research, I have decided to stick with the 300 WBY atm, I am going to call Weatherby today and talk to them if I have options but I am happy sticking with the 300 WBY.

And Yes its an extractor issue is why I wouldnt be able to swap.

 

[FEENIX]

View attachment 128605

After a lot of research, I have decided to stick with the 300 WBY atm, I am going to call Weatherby today and talk to them if I have options but I am happy sticking with the 300 WBY.

And Yes its an extractor issue is why I wouldnt be able to swap.

There is nothing wrong with the .300 WBTY but I am not a fan of anything proprietary. Having said that, I have a .30 LARA that can shoot factory .300 Jarrett and .300 WBTY in a pinch. You can also do an Ackley improved version or 30-8MM RM. Just for your consideration.

 

[Texanjohn]

The 300 bee will kill anything on this continent. I'd like bigger, say 338 for griz, but the 300 Wby is a great round,and perfectly capable of delivering great accuracy,don't sell it short if you handload for it you will be very happy with it.

 

[Lahunter76]

I will be, I will be using
200.20x Berger's
IMR 7828 ssc
Weatherby(Norma) Brass
Fed 215m primers

Would like to pull 3k FPS with it in a 26" barrel. I will be purchasing a 1:9 twist 26" Hart at say a contour ranging from a 4-5.5 w/flutes and really looking at the McMillian Game Warden stock.
I feel this set up will rock anything in the Western Hemisphere that I would be hunting, no plan on big Browns......yet, but when I do....a 338 shooting 300 Berger's will be the plan