I have decided to try and modify a Win M70 XTR in 300 WM and was able to find a 375 Safari Express barrell that I want to put on it. Just wondering what kind of modifications I am looking at for my gunsmith who I will call tomorrow. The XTR's were push feeds and someone told me that will pose a problem with the extractor on the 375 barrel. Looking for any info. Thanks in advance. Posted on both rifle forums for different opinions.

there's nothing wrong with your extractor but the safari express barrel will have an extractor cut that you will not need and a coned breech that needs to be removed (I believe)

Frankly, I'd install a new barrel!!!!!

Not all smiths have done this.....find one that has....unless you want to learn at his (and your) expense. It's doable but there's more to it than merely rebarreling.

I'm doing one now but using a 338 win mag CRF action as a base and the learning curve is purely at my own liesure and fun.....You need magazine modifications.....and more.

I have just finished my coned chamber but have not yet cut the extractor groove.....That's easy.....but the lengthening of the action may be more than wanted. At a minimum the spaced (about 3/16 of an inch) must be removed.....then see what needs to be done.....I plan on ordering a .375 H&H magazine for mine from Numrich.....and then figure it out.

I am going to pose a question that ya'll need to understand is coming from someone who is technically challenged by wheel barrows and the differences between a oval point and a spade shaped shovel...
Is it possible to rechamber the factory 375 caliber barrel from the longer H&H chamber to a shorter 375 Taylor aka 375x338 chamber? And yes it may be that the cost is so prohibitive to alter a 300WMg length receiver to accept the much longer H&H round than it s worth to begin with - "free or low cost" factory barrel or no barrel....and just buy a new Taylor chambered barrel.
However...If it's posible and financially prudent for the necessary 'smith work on the barrel vs the cost of new Taylor chambered barrel...there would no changes necessary in the 300 WMg's bolt face, feed rails etc. and provide super close to H&H performance - see some of the other posts on the 375 Taylor subject with the same bullet selection as the H&H...in a lighter rifle with less recoil....which is the attractant for me.

I have a M70 300wMg SS Classic I am contemplating this with and think I would rather use a 375x338 configuration rather than go thru all the necessary hassle and expensive of altering the Standard Length Magnum M70's receiver to accept the H&H case...before whatever issues the barrel presents. JMHO
Ron

In theory the 375 Taylor would clean up the 375H&H chamber IF THE BARREL COULD BE SET BACK ABOUT .4".

As to the recoil. The 375 Taylor is close enough to the H&H that it is hard to tell the difference. I have found the recoil sharper than the H&H and in a lighter rifle the felt recoil would be more.

If one used his safari express barrel, cut off all the action threads, re threaded it and rechambered it to .375 Taylor and installed it to his 300 Winnie pushfeed action he'd have the equivalant of the 375 H&H at the least possible cost.