340 Wby in a Vanguard

[jsquig]

Would rechambering a Vanguard in .338 Win to .340 Weatherby be as simple as just reaming the chamber?

 

[hunter5425]

You need a magazine length of at least 3.7" for the 340 compared to 3.34" for the 338 and I don't think the Vanguard magazine is long enough unless you want to go single shot.

 

[jsquig]

You need a magazine length of at least 3.7" for the 340 compared to 3.34" for the 338 and I don't think the Vanguard magazine is long enough unless you want to go single shot.

I guess that's my question really is how big is the mag in the .338 vanguard, because there is a .300 wby vanguard and the OAL of the 300 Wby is .5 mm shorter than the 340...

 

[Why not?]

The Vanguard comes factory chambered in 300 Wby, so they must have a magazine long enough.

Ted

 

[guntech]

If the headspace is correct now it can be done but it's tricky not cutting the belt any deeper yet cutting the chamber completely. It sounds easier than it is.

 

[RUPZUK]

My brother had this done 25+ years ago on a Howa, seemed to work on his but YMMV.

 

[c-fbmi]

I just did two rifles a few months back and one was my son's Howa, it worked out fine, but he did lengthen the bolt throw and magazine himself, it's not a big or complex job. It is quite a bit more involved on my Mod 70 Supergrade as I wanted a longer than standard magazine, as did my boy. As they come from the factory they will accept standard SAAMI COAL with little or no mag mods. The 340 is a definite step up from the 338 WM, I think you will be very happy and impressed with the 340.
As Dennis said this is just a touch tricky to get the headspace right on the money again, I used flat black spray paint and carefully ran the reamer in the last 10 thou or so 1-2 thou at a time until I could just see scuff marks in the paint on the leading edge of the belt, then went 1 more thou and cleaned almost all the paint off the belt shoulder but it still left a couple hints of it. This is about as perfect as one can redo a belted chamber in my opinion and the black spray paint worked flawlessly as I could see my progress on the walls of the belt. Polish 'er up and flush everything with brakeclean which removes all over spray paint and your good the screw 'er back on.