I was just at a gun show today and got a deal I couldn't pass up. A almost new 700 in 270 for $300, but of course I want to make it something more. Here are my questions.
If I convert it to a single shot benchgun can I go with a Magnum length cartridge (Most likely a 300 Weatherby)? I know I have to open the bolt face, the question is if I will be able to feed the cartridges easily.
Also, is is safe to open up the bolt face to .532 with a Sako type extrator?

"Yes" on all counts. Easy transformation...........

Actually, I dont think so... I think the 300 Win Mag is the biggest cartridge that will fit in a standard long action. Other than that, going with a 532 head size and a sako extractor would be easy, and there is a multitude of single shot followers to convert it to single shot.

I'm going to have to agree with bigstick on this. You shouldn't have any problem putting a 300 Wby through the bolt opening. I just got out my 270 and put a 375 H&H in nose first with room to spare. I say it's a go!

Sooner

The only difference between a "long" and "Magnum" Rem 700 action is the bolt face. I have rechambered M700 7mm Rem Mag to 7mm STW with no changes except using a chamber reamer.

The main consideration is opening up the bolt face. My gunsmith tells me that not as easy as one might suspect due to the design of the Remington extractor and using a Sako type extractor can be a safety issue. You have to cut the ring that encloses the case rim to install a Sako extractor and this cut and the new exractor line up with the bolt raceway. If you have a case separation, you could get a face full of hot gases.

An other consideration might be the magazine box and follower. Magnum cases are a bit larger in diameter than those of the -06 family and I don't know if Remington provides different magazine boxes and followers.

First off the action is long enough for any of the magnum cartridges.
In opening the bolt face it is common practice to utilize a Sako-type extractor simply because it is much easier than making the complex under cut (it is not round) for the Remington extractor. The Sako-type extractor works out well if it is properly installed. The safety issue may be exaggerated. The extractor is still held captive, to a certain extent, by the counterbore. If everything is done correctly it doesn't really line up with the race way. I have always been a little amused that this Sako extractor is such a deadly missile while the extractors on Mausers, M70s, and rugers, all of which typically take flight in the case of a severe overload, are no problem. Regards, Bill.

Thanks for info guys, I was pretty sure it would work, but not totally.

One of my favorite rifles began life as a 270Win and is of course Rem 700 based. It is now a 30-8mmRemMag(full length H&H brass)and wears a Sako extractor,with no other mods.

The 700's only come in two lengths,medium and magnum. The '06 action is the same as the 375H&H action,the boltface is the sole difference. Followers and mag boxes interchange nicely..........

Yup, no problems.
I have done many of them. even from 30-06 to 300 RUM.
I am so glad someone else knows that the safety issue about Sako style extractors is a farce.
Of course they must be properly installed.

Celt