I have a new LW action, a new Green Mountain 25 cal. barrel, 200 rounds of new 25-20 WCF, and reloading dies for the same. My question is should I put together a rifle in 25-20 WCF.?  I question this because finding 25-20 WCF ammo is very difficult and sometimes impossible to find.  If the rifle is ever sold would it be difficult to move it.  All work would be done by the best professionals.

Build it. 
It's a comfortable to shoot and highly accurate cartridge. You have 200 rounds to start with and the brass should stand up for more than 10 reloads. (I have more than 20 firings on much of my brass without loose primer pockets, splits, etc.). The brass, otherwise, is hard to find and can be expensive.
Loading is easy as long as components are available. I recommend CCI BR-4 or Federal 205-M primers, but some others may be equal or better. Less than 10 gr powder (Accurate 4100 or Ramshot Enforcer works for me) per round gives 700+ rounds per lb. (thrifty!). Excellent bullet moulds are out there already or can be made especially suited to your barrel & chamber. (120gr +- performs in my 10 TW Douglas.) 
It should be a fun project and produce rewarding results. 
Welcome to the Quarter Bore Corps.!

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20 pcs. 17.98

not as costly as some

Brass on Gunbroker for $65 per hundred.

I built a 25-20 wcf on an 1898 Springfield action but it is of course a single shot.  I had a used 257 Roberts barrel that had been on a Mauser action which after cutting of the threads was still long enough to re-thread and fit to the Springfield action.
The barrel has a 1/10" twist in deference to the standard twist for the 25-20 at 1/14"   The project turned out well and the rifle shoots very good but has a distinct preference for bullets intended for the 25-35.  It has turned in some sub MOA groups with the Bullshop 117gn flat nose gas check.  Its favorite loads pushes this 117gn bullet to 1740 fps so exceeds the performance of the 32-20 with its standard 115gn bullet.

bullshop - are you "the" Bull Shop bullets (You need to Login or Register to view media files and links) located in MT? If so, you might mention the fact that you sell 25-20WCF loading 'stuph', which I use in my Win Model 92 for pistol caliber silhouette. 

Another source I've used is Load-X (You need to Login or Register to view media files and links);

The only drawback for both is you need to call and order over the phone. Neither is set up to order on-line. 

I do not recall which of these two sells what, but between them over the last year I have purchased 200 cases, 200 loaded rounds and 300 bullets. All work great and was happy to find them. The story I recall is that one of these two purchased 100,000 cases from Starline at one point. Whatever, it is good brass and no problems with same.

Also, once things return to "normal" (whatever that is) Win will likely make a large run of 25-20WCF cases once again. In a pinch, one can always purchase loaded ammo at an exorbitant price from GunBroker and the other auction sites. Then you will have the brass.

Believe JerryH has shot a number of 250s with his 25-20WCF rifle. Very capable in the right hands.

boats wrote on Dec 26^th, 2020 at 8:19am:

25-20WCF with a GrnMtn Barrel. Unfortunately, when I suffered a couple of health issues and thought I wasn't going to be able to shoot again I sold it to someone in OH. I'll eventually get another 25-20WCF barrel for my CPA once I stop traveling for BPCR matches..

A few years back I built 2 #5 Remington rolling blocks in 25 caliber. The first I chambered in 25-35WCF. It has an unknown to me barrel in 9.5 twist (estimate) and shoot better than I do with 117gr Hornady RN. The second I chambered in 25-20WCF . It wears a Green Mountain 25-20 barrel with a 14 twist. It shoots 86grn Remington 25-20 bullets accurately. Neither have seen cast yet.
I think the 25-35 should handle bullets from any mold I have (65gr to 125gr) but not sure of the 14 twist 25-20. How heavy will the 14 twist stabilize.
Spring is only 3 months away and need to get some loading done. 
WW