How easy would it be?

[.50cal packer]

I have a Remington 700 .300 Rum. I’m wanting to change that to a .340 Weatherby. With the same size bolt face and magnum action and cartridge length; Would it be as simple as a barrel swap? Please let me know, what I’m missing here. Thank you in advance for any information on this.

[taylorce1]

It can be as simple as a barrel swap, all depends on what you really want in the end.

[T. O'Heir]

More than just a barrel change. The RUM is rebated rim, rimless cartridge and about 20 thou longer in case length. The Weatherby is a belted Magnum case. Rim diameter isn't the same either. Only 4 thou difference though.
The other thing is that the Weatherby ammo starts at about $75 per 20. And you won't find it in small places.

[std7mag]

Don't know where you think that, TO.
RUM rim diameter is 0.532" 340 WM rim diameter is 0.530".
So bolt face is the same.
As far as the RUM not having a belt, and the Weatherby having one, so what?
The new barrel would accomodate it.

Yes, simple barrel change.

[.50cal packer]

Ok. Thank you all that have answered! This is a first for me, as I’ve never tried to do a build. As simple as switching a barrel out may seem, Ive never done it. I planned on getting the new barrel from NSS and having a local Smith take care of it. I don’t have the gauges and I’m not comfortable enough to do it. But I didn’t know, all the little idiosyncratic things, that potentially, could make this a no-go.

[taylorce1]

Sorry, I didn't have much time to reply earlier and expound on what I said. Yes, you can simply have a .338 caliber barrel installed on your .700 with the chamber reamed to .340 Weatherby. It should work well with maybe only minor tweaking any competent gunsmith can do after installing the new barrel.

However, if you're going to spend money on a new barrel you should consider doing more to your rifle. I'd blueprint the action and add precision ground recoil lug at a minimum and consider a new trigger. If it's in the budget I get a different stock as well depending on what you have for a factory stock.

[.50cal packer]

Taylorce1
Excellent idea! Blueprinting the action and getting a custom recoil lug. That hadn’t crossed my mind. But would certainly be worth the upgrade. Yes, the trigger in mind, is a TriggerTech. I’m certainly not going to put the X-Mark down. But, I’m also not 100% confident, in them either. People will argue that. But it’s my choice. I am looking at stocks. My 300 is a SPS. So nothing extraordinary. I’d prefer solid fiberglass and adding a mercury reducer. The problem I see, is that all of McMillans stocks weigh around 2-2.5lbs. Kelly has said they can add extra weight. As I’m wanting this rifle to be a minimum of 10.5 to 11lbs. This also leads me to question what was the main point; The barrel. Trying to figure out the right contour. Yes, this is going to be for hunting. Any advice on other stocks and a contour would be most appreciated as well.

[taylorce1]

First off what kind of hunting is this going to be for? I've chased deer and elk with an 10 lbs rifle and I can tell you it isn't something you want to carry very far or all day. One poster on another forum stated the biggest issue with most custom builds is Weight and Wait, and I know I made both those mistakes with my first custom build. If you're making it heavy to mitigate recoil there are other ways to do that, remember hunting rifles are carried far more than shot.

Second, what is a .340 Weatherby going to do that can't be done with a .300 RUM? I can't think of one animal that won't fall as easily to the .300 RUM. I'm not against building the rifle you want, just don't be expecting to see a significant difference.

Third, rather than build a .340 have you considered a factory rifle? If you watch online sites you can probably pick up a Mark V for less than you can build. Again I'm not trying to talk out of your build, just giving you options.

As far as barrel contour I'd probably stick with the Remington factory magnum contour, just to keep it simple when ordering your stock. You might take a look at Grayboe and Manners stocks if you're willing to drop the cash on a McMillan. With a credit card I think Manners will send you a stock to handle that doesn't have an inlet so you can get a feel for it.

[std7mag]

50Cal,
What Taylorce says is true.
I built a Custom Mauser. Weighs 10 lbs without ammo. Not one that i carry far, or often.

[BusGunner007]

You might be money ahead by selling the. 300 RUM and buying a Weatherby. 340.

At least your present optics should still bolt on.

Kind of a can of worms situation.
But we have to dream.

[std7mag]

Local shop to me ( central PA) is selling some used Mark Vs in the $700-800 range.
Stocks need some loving. And i'm not sure of the bore condition.
But they are around.

[.50cal packer]

Ok. So a little background information, will be of help. If after the explanation, you still feel, like this transition is a stupid or a bad idea, I can and will respect your opinion. I’m not wealthy and don’t have money to burn.

I’m handicapped. As in can’t walk from the front door into my garage without my cane. Once I arrive at a place, if it’s to far of a walk, which isn’t far, a wheelchair is the method of transportation. So carrying a 10 lb rifle isn’t a big issue. Simply because, I will never traverse hills, valleys, mountains or miles upon the plains. It’s as simple as being brought to a ground blind and sitting. So yes, the weight was to help mitigate some recoil as was the mercury recoil reducer I had previously mentioned.

Now, do I need a .340 Weatherby? Nope. The 300 Rum is more than enough for everything. In fact, I wouldn’t be gaining much in energy, but would in recoil. I’m relatively young, 35 yrs. When much younger I hunted quite a bit. Now if I can go on one hunt every few years, I’m doing pretty well. With that in mind, I decided a few years ago, to make my hunts unique. As in exotics. Animals, I’ll never get to see in their natural habitat, especially on a different continent. Hell, most animals on this continent, I won’t see. However, none of the big five are on my bucket list.

So, when the wife says, you feel like going on a hunt, I use this term loosely, because they are in high fence areas. I want to take her up on that offer. I’m really interested in African plains game. So, when I say I want to hunt Nilgai, Kudu, both species of wildebeest, I want the gun to be something different. Why the .340? Why not. Is it expensive to shoot? Extremely! But if I shoot the gun 4 or 5 shots a year, a box will last a while. It’s something different I can hand down to my boy, when or if that time comes.

A build is something I’ve never done and thought I’d try something new. I also know all those animals, I mentioned, don’t require a 340 Weatherby to harvest. In fact, I’ve seen some in articles taken with things as small as 7mm-08. But.... I’m not wanting to shoot a 7mm. I’ve taken several deer with my 300 win mag. So am I having a pissing competition with myself, trying to go bigger? Probably so. So if anything I have said, makes you think, I’m stupid for wanting to do this; Seriously let me know. Buying a new MKV would be cheaper, I’m sure.

[taylorce1]

No, you're not stupid at all and I'm more than willing to help. I have just made enough mistakes building rifles, so I'm always willing to share my experience if it will help. Here is what I would recommend that you choose a gunsmith first.

The reason I say get a gunsmith first is think of him as your guide. Tell them your budget, physical limitations, your desired rifle weight, and what positions you'll mainly be shooting from and they can help you pick the best parts to get you the desired results. Also if you'll mainly be shooting from a ground blind you may not want a 26" barreled .340 WBY MAG, as it may be too long to manuver well inside the blind.

Remember barrel and stock are the easiest way to control your rifles weight and balance. There isnt much you can do to change the weight of the reciever especially if you're wanting a heavy rifle. Just look at a few barrle makers web sites, a lot will give you a ball park weight of a specific contour.

Good luck and if you have questions dont hesitate to ask.

[std7mag]

50Cal,
Again, my sentiments mirror Taylorce. Kudos to you for going out and doing what you want!
I know for myself, i don't need any more rifles. But i want more.
Just don't tell my wife!

A good gunsmith will help you choose weather a recoil reducer in the stock, and or a muzzle brake may be better for you. Someone local to you that could possibly see you shoot may help.

Best of luck!
Let us know how it turns out!

And only stupid question is the one not asked.

[.50cal packer]

Thank you to everyone! All this information is greatly appreciated!

[old roper]

.50cal packer, the only problem you may have is feed rails and follower. You could buy dummy rds from Wby.

http://www.weatherby.com/dummy-rounds.html

I had 300Wby build on Rem action, same case as 340 and Wyatt makes magazine box little longer and I had that put in.

I didn't go from RUM case to the Wby. I have hunted with 300RUM got pretty nice bull with it.

Got to do what you like.

[Nathan]

As I’m wanting this rifle to be a minimum of 10.5 to 11lbs.

You are a smart man. Weight is a good thing for shooting.

Don’t forget to include your scope and mount in your weight calculation.

Next, make sure you put enough weight in the butt of the stock. Too many folks put it all in the barrel. Barrel heavy rifles are a pain in the field. I would rather have a heavier gun than a barrel heavy, but lighter rifle.

Weight is a stabilizer in the field. It alone makes field accuracy easier.

A weatherby Mark V is 8 lbs. Add a std weight 18 oz scope and 8 oz mount and you are at 10 lbs. sling? Buttstock ammo holder? You are there.