Home Forums Hunting & Shooting Single Shots Browning B78 Rechamber

A guy where I live has a Browning B78 chambered in 243. I have a Blaser R93 with a 257 Wea. barrel, and I would love to have a 240 Wea. barrel, but Blaser does not offer it. Would it be possible to just rechamber the B78 to 240 Weatherby Mag? I'm not a gunsmith by any means, so I really have no idea. Thanks.

IIRC, the .240 Weatherby has the same head size as the .243, but has a belt...which means that the .243 chamber would not clean up.

That would mean either shortening the original barrel considerably, or a new barrel. Note that I Am Not A Gunsmith, but a look at the chamber drawings will tell the story.

I agree with BB, the .240 Weatherby reamer would not clean up a .243 Win chamber. A better idea would be to cut it out to a 6mm-06 or 6mm-06 AI. You can meet or slightly exceed the .240 Weahterby velocities and brass is cheap and readily available everywhere.

Yepper, punch it to 6/06 and rock on!

Dober

If it were me, I'd ten times rather rebarrel a rifle to a .240 Wby that I WANTED , than rechamber it to a 6/06 that I don't want!

Building a rifle and satisfying a WANT are emotional decisions. Why would anyone want to build a rifle on someone else's emotions?

GH

The .243 case is fatter than the .240WM case, both just ahead of the extraction groove (belt area on the WM) and at the .243's shoulder area (about 3/4 forward, along the WM case body) - so I would think (as posted above) a less-expensive rebarrel would be indicated, since the old barrel would most likely have to be shortened almost 3" at the chamber end, rebreeched (threaded, etc) then rechambered.

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Preach on, Brother !!!

A B78 is a fine rifle. However, it is not the same internally as a Win 1885. Make double sure you want to put the effort & $$$ into that upgrade. I like B78's, Browning 1885's & Winchester 1885's. They are all quality guns.

I am not trying to discourage you. I am simply suggesting you make sure you have the gun you want before you start the process.

There are companies that do quality rebore jobs on fine rifles. Maybe you could obtain a smaller bore barrel for your Blaser & have it rebored & then chambered in 257 Wby (that's what I would do). If you choose that route, be sure to confer with the rebore specialist to make sure you get the correct bore diameter. Some require a specific step-up. In other words, they wouldn't rebore a .277 to .284, for instance.

6MM-284 is another option you could consider. The smith might have to modify the extractor a little bit to accomodate the rebated head of the 6-284 case. The head is the same size but the 284 case is somewhat larger. 6-284 gives almost the exact performance as the 240 Wby but as above if you want a 240 Wby the only real option is re-barrel. Good luck
6MMWASP