There may have been a Gun Digest Annual article on it back in the 60s or early 70s. For forming it is probably just shoot a 25 Krag cartridge in it. One of the old wildcat cartridge loading manuals should have data. Sorry I can't be more exact offhand. I just have a normal 25 Krag.
Almost instant update. I took a guess and was able to put my hands on the 1963 Gun Digest and there it was.

There is loading data in my  P.O.Ackley handbook 1980 printing
for the 25 Krag Ackley Improved.
The FBW modern action should be OK for the max loads
listed. It is quite a hot number.  He sayes that load data for the 257 Roberts Imp can be used as the krag imp has almost 
identical capacity
Meanwhile, data from oneatatime for the std 25 Krag
could be a wise conservative starting point.
beltfed/arnie

Beltfed, thanks for the info.

Westerner, those cases aren't really inspiring me. I take it those were the first and last you made. Heck, I married a red headed woman so I don't suppose this is going to be any harder than living with her for 40 years. LOL

If anybody else has any info it is welcome.

Bob

I'm not sure that the Improved and Ackley Improved are the same. I'm back from errands now and will see if I can scan the article in the Digest. Stand by. Well, the article title was the 25 Krag Improved but it turns out that the work was done by Ackley who, of course, called it the 25 
Krag Ackley Improved! It also says that cases are easy to form. First the 30-40 Krag case is necked to 7mm and then to 25. After a trim it is fireformed. Scanning the pages was a bust as I couldn't get it right on the scanner so I tried to photograph it and managed to kill all the pics I had on my 32 gig card;-( Anyway, I reduced the pics so I could load them here and some of it is almost readable. One of the other little facts in there was that Ned Roberts had tested various barrels in the 25 Krag Niedner and decided that in a strong rifle the 30-40 case was good to 48,000 psi. (The earliest loads were developed on a Krag action which limited things to 42,000 psi). Ackley was not known for holding back but the rifle that he developed these loads in was a high wall that was re heat treated and he used a medium heavy Douglas barrel. So with a little imagination you might be able to read a bit of these pages. Good luck. I am a little pleased with myself for deciding to try the 1963 issue first as it has been 62 years since I purchased it new. If you use some Ctrl + Ctrl + es, it will help.

I had a FBW rifle in 30-40 Ackley for a brief time before my Borchardt in that caliber was finished.  The rifle is extremely strong and quite suitable for that cartridge.  The main reason that I got rid of it was I dry fired it and broke the firing pin and found that parts were hard to come by.  Outside of that it was a well made rifle.  Now on to the 25 Krag.  You will need to do a chamber cast to see which type it is chambered for as the 25 Krag Improved came in regular length and short versions.  If it is the long version making brass will be easy.  Get a Universal Nexk Sizing Die in 28 caliber and one in 25 caliber.  Neck down a standard 30-40 Krag case to 28 caliber and then down to 25 caliber.  The intermediate step might not be necessary but won't hurt.  Then load up a light charge with a bullet seated so that it touches the lands and requires a little to seat and touch it off.  Instant 25 Krag Improved Case!  I have a 7mm Krag Improved and I had custom bushing sizing die made as it has a tight neck chamber.  For bullet seating I use Vickerman Dies for all of my wildcats.   Case Capacity should be about 60 grains full to the top of the case which is 4.0 grains more than a 257 Roberts, so I would start with starting loads for the 257 and work up.  If you don't hot rod it you will only need to neck size.  Check the rifle twist to see what length bullet is suitable and have fun!  Tom

YOU GUYS are GREAT. This is what I needed to get started. My friend has many different calibers and I am sure he has some of the dies we can use to start the process of getting the 30-40 case to fire forming stage. Much experience and wisdom shared here and we appreciate the help.

4060MAY, 60 years!!!! This one is one that came along late in my life. I was 40 and she was 24. Yeah, I know. Not smart. BUT 40 years later we have managed to hold it together. I tell folks two things; I am tougher than I look and I should get a medal since there is no way of telling how many good men I saved by marrying her. LOL

Thanks again everyone.