I'm willing to wager that you won't find many BP shooters here. Especially those shooting BP in a .25 caliber.

That being said, from BPCR Silhouette experience, you most likely won't find much difference in accuracy, but may notice a drop in MV.

As no one else has answered you, I hope this may be of some help.

Give it a try and see what happens. You may be pleasantly surprised!

Jerry_H

There are black powder shooters here, but they are definately in the minority.  I don't think that black is much/if any handicap in 28 caliber and above.   25's, and smaller, seem to have had less success using black.   

Thanks for the replies fellas.
    SSShooter I have only fired about 25 rounds with BP in the 25-20. I have only shot at 25yds to establish a sight zero (rifle is new to me). I'm trying to develop a user friendly fixed round to use for squirrel and cottontail hunting. Rifle is an original low-wall with SST and an original factory 28in #1 bbl.  Barrel has (what appears to be) excellent+ bore, slugged at .250 bore and .2565 groove.   
   I was using the following for the first 15 rnds(bench rest, wiped after each five rounds):
Case: unfired Jameson (sized with some standard RCBS dies which unfortunately had reduced the neck ID to .255 and was apparently deforming the bullet badly)
Primer: Federal small pistol
Bullet: Buffalo Arms 86gr., 1/20 alloy, sized to .257 dia. RNFP, SPG lube. Bullet seated out to just engrave the first driving band
Powder: 17gr. Swiss 3FG. 12in drop tubed, topped with .030 thickness .25 cal Walters vegetable wad.
Compression none (well.. not more than a 16th as I have always found the Swiss powders to respond better with minimal compression in my "big bores")
  All shots at 25yds rest. I had pretty dismal groups for the first 15 rounds with no better than 1 3/16 x 1/4in. 5 shot groups (center to center). The last 10 rnds I had decreased the neck tension to .002 and fired two similar 5 shot groups that had 4 rounds in 9/16 x 5/16 with a 5th  shot as a flyer that opened the group to 14/16 x 13/16. The very next day I injured my back and have not been able to shoot for the last 7 months. 
  As soon as I can I will try decreasing the neck tension to "thumb seating pressure" (CH4D collet dies) and using a .258 and .259 bullet (RCBS-25-85-CM). I am new to these small bore cartridge rifles but have had some great advice on smokeless loads from some of the forums quarterbore shooters. I welcome any and all advice!!
Thanks, Tom

Thanks Ken,
   The Swiss 2F granule size is so much smaller than Goex or the old Dupont 2F, it seems like a natural choice. I know the smokeless loads are accurate and less trouble than the BP, and is the intelligent choice for competitions. I don't do much competitive shooting anymore, just mostly take my rifles for a walk in the woods, chasing hapless squirrels and rabbits. The inconvenience of BP never seems to come close to the enjoyment in that situation. I was hooked on large bore black powder single shots back in the 60's and I guess it still appeals to me, but as the good Major said "Only accurate rifles are interesting"
Thanks, Tom