Re: Getting Started
The nice thing about the Rem 700 receivers is that any receiver chambered in a standard '06 class round or standard magnum(7mm Rem Mag, 300 Win Mag) are the same length as the 300 RUM length receivers. This is why you can build so many different chamberings on the Rem 700 receiver.
In fact, my 2000 yards rifle in 338 Kahn(338-378 Wby Improved) is built on a Rem 700 ADL that was originally chambered in 270 Win.
Bullseye pretty much told you what you needed to know. There are a couple little things I highly recommend for rechambering a factory rifle such as the Rem 700 from 300 Win Mag to 300 RUM.
First and formost, even with all the machining in the world to true up the receiver and barrel, you are still dealing with the factory pipe. IF you want a sure thing in your finished rifle, get a new barrel fitted.
If you simply want to rechamber your rifle to try a more potent round, go for it. Most often they shoot very well rechambered, a few never will.
If your rifle shoots well now, it will probably shoot at least as well after being rechambered properly to the larger caliber.
As far as the Rem 700 300 win to 300 RUM conversion. There is no much to it. Only modification that may be needed on teh bolt is to increase the bevel on the inside lip of the bolt face. I have seen a few instances where this area was not releaved enough for the larger RUM case head. Even though the rim fits easily in the bolt face, the body contacts the bolt nose. Some will actually chamber this way if the case is close to touching the bolt face but acccuracy generally suffers badly. In severe cases, the case will be driven back into the bolt and stick there. Nothing dangerous but a little spooky for a rifle owner that is not sure why it happened.
This is one of those small things that need to be checked. May only see it once in a 100 rifles but that one time will save headaches when you catch it.
Other then that. SOme Rem 700s chambered for standard magnums need a few thousands taken off the feed rails to widen them. Again, I have seen some that needed nothing done at all to them, just an area that needs to be function checked before shipping the rifle out.
I also like to change the standard mag box with a RUM mag box which is significantly different. This simply aids feeding by holding the cartridges in proper stager angle with each other. Some Rem 700s with standard mag boxes with spit the first round in the mag when teh bolt is opened without a REM mag box being fitted. They are cheap so I just do it, again to prevent headaches down the road.
The final addition I highlyrecommend is to fit the rifle with a Holland Comp Recoil Lug. These lugs are nearly twice as thick as the factory lug and simple will not flex or bend under recoil. The dramatically increase the rigidity of the entire rifle system. They are also easy to fit to the barrel but the barrel needs to be pulled.
I do all my chambering on pulled barrels anyway so this is not a problem to set the barrel shoulder back the proper amount when you have the barrel dialed in on the lathe.
An upgraded recoil pad is also a common request when going from a standard magnum in the Rem 700 to a RUM round, especially on the older rifles where the stock will be reused.
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