What would be needed to convert a model 70 375hh to a 375 weatherby. i did a search but couldnt find a definite answer, come say the barrel needs to be set back and others say just buy a reamer..anyone got any ideas

Do a chamber cast first. Hard to know what the original fatory chamber looks like. If it is straight and reasonably tight, the Weatherby reamer would clean the chamber up, and off you go. That is how it worked out on my rifle.

The nice thing about turning the barrel back a couple turns is that you end up with a nice fresh throat.

If you order a reamer I recommend you have it ground to the new factory specs which give you a .37" freebore. "Freebore" may be a misnomer in that it's not like there is a bunch of slop in there.

LD

Just buy a reamer.....and O....don't forget.....remark the barrel.

quote:

Originally posted by grizzinater:
What would be needed to convert a model 70 375hh to a 375 weatherby. i did a search but couldnt find a definite answer, come say the barrel needs to be set back and others say just buy a reamer..anyone got any ideas

It is essentially the same as the 375 Ackley improved. In an ideal world the case would headspace off the shoulder and you would need to set the barrel back to provide good support for fireforming. Being belted, some people simply run the reamer and their done. Since belt and case dimensions can vary greatly from that of the chamber, I prefer to set the barrel back to snug things up a touch over the usual slop from the factory.

The normal reason the barrel is set back on an AI conversion is to make sure the factory cases that headspace on the shoulder are a crush fit.
With the belted cases this is not an issue. However, I just took the case measurements I had and drew them up and as I see it the WBY will JUST BARELY clean up the shoulder. Using reamer dimensions might give me a different answer.

Again this could be my info or drawing skills giving this answer. A chamber cast and reamer dimensions could answer for sure. If I was going to the trouble of rechambering I would set it back one turn. Get a new chamber wall all the way and new throat.

Time for coffee. (Revised after coffee)