Besides the Model ’73 I told you about, I have a Model 1892 in .25-20.  All I shoot in it is cast bullets.  I can tell you what my experience has been.

First off, I have found the .25-20 to be a good calibre for cast bullets.  The smaller calibres have the reputation of being difficult to cast and load for, but I haven’t found that to be true of the .25-50.  Be sure your mould is in good condition, size your bullets 0.001” oversize, use a good lube and be sure to bell the case mouth slightly before seating.  Other than that, the normal rules apply.

Cast bullets need a good bore to shoot well and this is particularly true of the smaller calibres.  What I look for in a used gun is a bright, shiny bore with strong rifling and no visible pitting or wear.  You really want a bore that is near-perfect; otherwise, the bullet will leave a streak of lead on the rough spots and each bullet will leave a little more.  A lot of .25-20s date from the era of corrosive primers and rough bores are common.  If your rifle was made before 1920, it definitely used corrosive primers and it probably has a rough bore.  Rough bores can shoot jacketed bullets OK, but not cast.

I attached a look down the bore of my Model ’92.  It was made in 1914.  It’s OK but it’s not perfect.  If your bore looks any worse than this, it probably won't shoot cast bullets well.

.25-20s do best with low-velocity loads and this is especially true for cast bullets.  The original ammo shot an 86-grain lead bullet at 1,460 f.p.s. and that’s a good place to start.  The loading that I settled on is a plain-base 85-grain bullet over 7.0 grains of IMR 4227 for a velocity of 1,356 f.p.s.  The alloy I use is wheel-weight metal and the mould is RCBS #25-85-CM.  With a hard alloy like that and slow velocity, the bullets pass through small game with minimal meat damage.  For target shooting, it’s mild and gentle to shoot.  In my rifle, group size is ½ inch at 25 yards and 3 inches at 100 yards.  

For anything faster than 1,500 f.p.s., you'll need a gas-check bullet and a harder alloy.  I’ve tried a 65-grain GC bullet, Lyman No. 2 alloy and 10.5 grains of IMR 4227 for a velocity of 1,950 f.p.s.  Accuracy stayed good at 3 inches @ 100 yards.  But if you’re after varmints, you really need a proper varmint bullet, not a hard-alloy casting.

You asked about rate-of-twist.  Winchester made its Model ’92/.25-20 barrels with a 1:14 twist.  That’s what mine has.  

The Greenhill Formula is the standard method for determining optimal rate-of-twist. The link down below will take you to the vCalc.com website where you can do the calculation yourself.  You will need to know the diameter, length, specific gravity and speed of the bullet to do the math.  I attached a pic of my 85-grain cast bullet.  For it, the calculation worked out to 1:15.  As my gunsmith Steve said, “It’s OK to spin them too fast, just don’t spin them too slow”.

If you’re getting a custom barrel made, talk to your barrel maker.  He will know more about this than me and he will give you better advice.

Good luck.  Let me know how things work out.

Pete

https://www.vcalc.com/wiki/AndrewBudd/Greenhill+Formula+for+Optimal+Rifling+Twist+Rate 

mrcvs said

antler1 said
I just returned from Tulsa and I must say that any higher condition Winchester lever guns I looked at definitely have NOT gone down in price.
  

You can price anything as you wish.  But were they actually selling?
  

 I walked in the Tulsa Show at 10am Friday and kept moving most of the time until 7pm. Came back Saturday and did the same from 7:30 to 4pm until I no longer could. It was fun but I'm still stiff. Saw a lot of money changing hands next to nice Winchesters, not much movement on medium to low condition guns. It's hard to tell what the guns sold for, you only see the asking price on the tag. I did ask several friends as they bought, prices were high on nice guns. I paid attention to 1866 rifles and anything worth owning went 8-12k. I spotted four Friday morning and Saturday three were gone. Deluxe grade levers with condition were selling. No shortage of money. T/R

steve004 said
These rifles were fine (great) at the beginning of my collecting.  But as time went on, why buy something that would be a downgrade of what I already have?  And for many of us, a lot of time has gone by. I think we naturally evolve toward better condition, greater rarity, special features and so on.  So there is less demand for these rifles among established collectors, and with fewer and fewer new collectors coming in, it's logical the demand for these pieces would be going down.  And of course when demand goes down, prices go down.  
There are a great many established collectors out there.  And many are still quite thirsty for more.  But it's what they are looking for is the significant variable.  I think that's why for several years we have progressively seen startling price jumps for the pieces that make established collectors salivate.
Let me add that I've kept many of my lesser pieces.  I've had many for a long time.  And even though I still like them a lot (and some are favorites), I feel I have enough of them.  
  

Yes, but in YEARS of searching, I could not find a better Winchester 1894 SRC in .32-40 than the one posted in the beginning of this thread.  Where are they?  Did anyone see any at Tulsa?

Zebulon said
I will only add what my old mentor told me a long time ago,  which has saved me from grief more than once. "When the elephants fight, the grass gets trampled."
  

And we've all seen a lot of trampled grass

There are a great many established collectors out there.  And many are still quite thirsty for more.  But it's what they are looking for is the significant variable.  I think that's why for several years we have progressively seen startling price jumps for the pieces that make established collectors salivate.

Let me add that I've kept many of my lesser pieces.  I've had many for a long time.  And even though I still like them a lot (and some are favorites), I feel I have enough of them.  

Zebulon said

If we are talking about moderate condition 1886 or 1876 models, that is quite another. For all their notoriety, relatively few were manufactured. 
I have yet to see a 95% condition 1886 of any style go for less than an eye-watering price. 
  

I usually don't buy average condition guns.  But I don't normally by 90% either.  I'm not into safe queens.  All I know is the market has been good for me.  I recently bought a 73 Musket and a 73 22 Cal.  They are in moderate condition but I got them cheap.  And they fill a slot.  The 22 is a project.

The last 86 I bought, as you say, was not cheap. 

If we are talking about moderate condition 1886 or 1876 models, that is quite another. For all their notoriety, relatively few were manufactured. 

I have yet to see a 95% condition 1886 of any style go for less than an eye-watering price. 

mrcvs said

antler1 said
I just returned from Tulsa and I must say that any higher condition Winchester lever guns I looked at definitely have NOT gone down in price.
  

You can price anything as you wish.  But were they actually selling?
  

Yes!! A lot of Benjamins trading hands at high condition tables. I sell as well as buy to upgrade collection and it was a good show for me

antler1 said
I just returned from Tulsa and I must say that any higher condition Winchester lever guns I looked at definitely have NOT gone down in price.
  

You can price anything as you wish.  But were they actually selling?

1. While there are some young collectors of the genre,  it seems to be mainly a disease of the elderly. Who are dropping like flies as the 21st Century proceeds. 

2. Those guns are not really rare - there are increasingly more than enough to go around. Those in unquestionably perfect condition are locked in institutional or family collections that seldom enter the market. 

3. Like it or not,  FN-sponsored production of the 1873, 92, and 94 appeal to many Winchester fans and compete for market share with original Winchester lever actions in less than mint condition. While you might not care whether a 95% Model 92 can be shot because 44 WCF is hard to buy in shootable quantity,  there are apparently a large number of ignorati willing to spend fifteen hundred bucks for a very nice new 92 that shucks and shoots 357 magnum pistol cartridges. Their plastic works as well as yours and this choice once did not exist. 

4. The Old West of fact and fiction now competes with G.I. Joe and his descendants, apparently all of whom are or were long range snipers obsessed with 1000 yard targets.  Quigley helped Shiloh and C. Sharps, not Winchester. 

Perhaps an apostate's opinion, but the numbers don't lie.