The 2520 Win is a shorter cartridge designed to function in the Model 92 Winchester lever action rifles and a few others. I think Marlin also made rifles in that caliber. The 25-20 SS is a longer shell from the Black powder era. It kind of looks like a grown up Hornet. The two are different. The 25-20 SS is I believe a better cartridge for Target shooting up to 200 yds and can be shot with smokeless powder. Now having said it came from the black Powder era I must admit I have not known anyone to use Black powder in a 25-20 SS. I suspect that fowling is a real issue. HTH regards, FITZ.

  As Fitz says the .25/20 Win. was especially developed to be used in the Win. 1892 because the SS was to long for the action. Water capacity of the two is slightly different with the .25/20 Win. having a capacity of 27 grs. of water and the .25/20SS having a 30 gr. capacity. The .25/20 Win. case is 1.33" long and the .25/20SS 1.635".

I've shot the .25/20SS quite a bit with BP. In fact with the exception of one load worked up for 4227 that's all I've ever shot in it in either a re-lined Low Wall or an original Stevens 44 1/2. Both have been shot fixed and breech seated.

  I have gotten groups, at 100 yds., below 1", but the norm is closer to 1 1/4" if breech seated and wiped out between shots. Best BP loads run about equal to the smokeless load. I've used it Squirrel hunting a few times with reduced loads of BP and out to 50 yds., without wiping between shots, it has enuf accuracy for head shots.

Merwin,

  For the original twist in the Steven 44 1/2 about the most wgt. you can get away with reliably out to 200 yds. is 75 grs. I think Brent will back me up on this.  A very few guns, for some reason, will handle up to 80 or 85 grs., but that will more than likely restrict the maximum accurate range you can work with and get acceptable accuracy. The thing to do is see if your gun will handle that Lyman bullet of yours and what the maximum range you can get accuracy that's acceptable for what you want to use it for. In any event I'd look for a 75 gr. mould.

  I use an old NEI PB bullet which is marked 60  257 (actually weighs about 70 grs. cast 1-25), which I don't see listed in the newest NEI catalog I have. As mentioned in a previous post I haven't done a lot of smokeless powder load development with this round but 8.0 grs. of 4227 and a Rem. SR primer do what I want from it. 

  This light bullet wgt. for the original twist is the reason most .25SS shooters today opt out for a 1-10" or 12" twist for target work. The 10" twist is what I have on my Low Wall and it will handle bullets up to possibly 120 grs., altho the bullet I use is 110 grs.

  The case capacity of the SS is really crowding the limit for fixed ammo BP use and a 110 gr. bullet. With smokeless you have to be careful as it's pretty easy to stretch primer pockets. That's experience talking!

How would the 25-20ss do for called coyotes (inside 100 yards?  Also, my rifle came with the Ideal loading tool with bullet mold.  Is there a way to know what weight bullet it will throw, other than casting one and weighing it?

Wings,

I think a good flat-nosed bullet cast 1-25 will do the job nicely on those Coyotes at the range you're thinking about.

  According to Lyman Handbook #27 the bullet wgt. cast from the Ideal #4 tool should be 86 grs.

MerwinBray, we need to talk about some bullet casting for these .25s.  Hint: can you say "Perfection Mould?"

Froggie

Froggie,
Perhaps we could get together at my house on a shoot weekend when you are up this way? I forgot about THAT mould. Are you going to try to make Timonium? I plan on going and am always looking for moulds while I am there, amongst other things. 
I have both Ideal 25-20ss and 25-20 wcf tools with decent moulds. They visually apear the same. I have cast from both but at different times and didn't compare them. I want to. I also want to run some of the .22 wcf bullets from another ideal tool I have. I can then size some for my .22 hornet and try some as is for my stevens tip up in .22 wcf. That gun has a dark bore, but I want to shoot it. I am looking to use it on the June squirel season we have here.
Merwin