Does anyone know whom makes these or where they can be ordered from? Thanks.

Pottsy,
The 300WSM works at a pressure that some consider too high for the Encore. The standard 300 Win will work just fine. If you reload the 30-06 JDJ would also be a fine 30 caliber round for the Encore.

www.matchgrademachine.com
they have the chambering listed as available for the encore.

Thanks everyone. Not sure that it is even practical, well most of my gun purchases aren't, but it is just one of those must haves for me lol.

You can do a Striker or XP, but unless you stretch the barrel out beyond 15", to say 17" or so, it really isn't practical. You'd need to load the 300 WSM down for the Encore to be safe, so you'd do nearly as well with the .308 in a 15", or go with the tried and true .300 Win Mag in a 17" if you want muscle. Alot of things we do are not necessarily practical, though.

I have a 300 WSM in a HS Precision. It has a 15" barrel. At present I am shooting a 165 Ballistic tip out of it. My velocities are running an average of 2830 FPS with no pressure signs. Accuracy is superb.
nmhunter

I'd love to have a Striker, I haven't been able to get one yet. I guess I have no issue with the straight 300 win mag, I've never actually shot one. I do have the wsm in a browning A-bolt, and love the gun.

J Larsson,
That is exactly the way it was explained to me. My next question is then why is the 500SW OK in the Encore. Its rim is larger that the WSM family and with healthy loads is going 60,000 PSI or more.

Ed, it's been a long while since I had anything to do with WSM's but I don't think anything has changed. Chamber pressure isn't the issue when it comes to action strength with these cartridges.
When the round is fired the case expands and grips the chamber walls, reducing back thrust. That's why we don't actually polish chambers to a mirror finish. We leave a very light cross hatch pattern after polishing, to allow the case to grab some meat and hang on. Same concept when honing cylinders in an engine.
Supposedly, and I agree, a short and very fat, stiff case doesn't grip the chamber walls as well as a longer case does during expansion. So if it's not gripping, it's moving rearward.
I don't think an Encore is able to handle that kind of back thrust. At least not for long before the pivot gets loose.

I should add that case body TAPER is also a factor in backthrust. The straight-wall cartridges tend to transmit less than the more tapered cartridges.

Good point.

Ranger,
Does opening up the bore, say to .416 on the WSM case have any affect on the amount of back thrust. The reason I ask, I have a .416WSM barrel on the Encore. Knowing the back thrust problem I don't load it with max loads. I keep the 350gr bullets around 2100fps.

Good question. I don't know for sure but the hairs on my neck say it might actually give you more back thrust, just from the bullet weight.
However, a bigger bore diameter does reduce chamber pressure in cartridges that share a parent case. Like the difference between 25-06 & 35 Whelen. But again, chamber pressure isn't the only issue with WSM's. Chamber pressure is measured perpendicular. We know any modern barrel can handle that. But back thrust is measured inline with the bolt or breech face. Can an Encore frame handle it??
Surely we could find some hard information on this somewhere. I may call Walter Birdsong tomorrow. He's in constant contact with people who know things, and has answered some stumpers for me before.

The way I see it is this... If JDJones won't chamber an Encore barrel in 300WSM because he doesn't think it's safe then I don't want one.

The case is too fat making the chamber walls too thin for such a high pressure cartridge.

Gotta draw the line somewhere....

$bob$

I agree with everyone. I have one in a Striker and love it. After 6 Antelope and 3 Mule Deer (all one shot drops) I'm extremely pleased with this caliber. I did yank the stock barrel and opted for a 15 1/2 Shilen Stainless benchrest with a custom muzzle brake from a gentleman in Cheyenne. It's the first one I can say that works. I can shoot this all day with no problem!