I want to rent a reamer and convert my 7mm Rem Mag to 7mm Dakota. A friend of mine is a machinist, and I want to know if the barrel must be removed from the action prior to reaming in a lathe. Also, how does one secure the reamer if the barrel is secured in the chuck? Do you hold it by hand, and if so, this seems kind fo dangerous. Any help from someone with experience would be greatly appreciated.

Sheldon

The conversion you describe isn't difficult at all, but to do it right requires specialized set-ups,equipment and experience that even a good machine shop may not have. The cost of the tooling required almost certainly will exceed the cost of having this done.You might also regret trying to this yourself if your friend runs into a problem. I'd really suggest you find a good gunsmith who has done this before ( verify this and get references) and pay the freight. Be aware that while any gunsmith worth his salt should be able to do this for you, that many actually never have and you don't want to wind up with a gun that doesn't feed for example.There are alot of people on this website who can suggest a good competent Smith. This way you will have a gun that will not only be safe but will feed and probably shoot straight. The only reason I do this work myself is that I'm a perfectionist and am so impatient that I can't wait the 6-8 weeks that most Gunsmiths take to get such a job done.

Here are a couple things to consider.

#1 the barrel must be removed, so that you can accurately measure the headspace. This will require a barrel and action vise, you either buy, or build.

#2 There are a few ways to hold the barrel on the lathe, either with a center/drivedog and steady rest, or a 4 jaw w/ the barrel through the headstock, and supported on the outside end with a cats head.

#3 In addition to the re-chamber, you'll have to have the open up the bolt for the larger case, and possibly the feed rails.

#4 If your machinist has never done this before, a job that would take a smith ~2 hrs might take him 8 hrs, and you might not be happy with the results.

#5 If you consider what you are going to be spending on brass, dies, and the work, you might just realize the actual increase in terminal performance is mute.

#6 If the barrel currently doesn't shoot that well, you aren't guranteed of an increase in accuracy, so, you might want to factor in a new barrel for the job.

#7 If you don't have target nobs on your scope, and a lazer rangefinder, you won't see any benefit in the 7 dakota, and, the money spent on the re-chamber would be better spent getting a lazer, and a top scope, and using the 7 mag to its potential.

Of the other 5 journeyman machinists in the shop not one would know where to start in rechambering a rifle. On the other hand I am inept at programming the CNC mills. Everyone has his area of expertise. Sometimes it's best to take advantage of that. Regards, Bill.