Caliber? Lube? Compression? Charge? Bullet behavior i.e. keyholes, inaccuracy, stringing etc? Details, we want details!
Regards, Joe

It just doesn't group with what ever load I've run through it. The load I have been useing lately is a 190gr. slug with 41gr. swiss 1 1/2,no compression,SPG lube, 20-1 alloy. I was thinking that the lands were to narrow to grab much with the PB fouling. All of my other guns have the lands and grooves about equal size.
With smokeless, it groups as good as I can shoot, 1" to 1 1/2" at 100yrds.

Have you tried a lighter bullet? I use a 170 gr. in my .32-40, and it has a faster 1-14" twist. With your 1-16" I would go a bit lighter, and see if it improves. 
I'm not fond of those narrow grooves myself, but I don't know if they could cause inaccuracy.

"My bad, I see the caliber's in the title. What alloy? What dia's are bullet, barrel bore and barrel grooves?


Mike;
    I'm with Joe here. Bullet fit is a critical factor - probably the most critical to my thinking. Not to ignore the other things which have been suggested but bullet fit comes first for me. As to bullet weight (and thus length), I shoot a 220 gr spitzer in my 14" twist .32-40 barrel, on the recommendation of B&D and the accuracy capability is fine. A friend bought a .32-40 with a 16" twist and the same weight bullet was recommended to him by B&D also. I would have bet money against it but the accuracy is super (better than my 14" twist). 
    I guess what I am saying is that I would slug that barrel and find out just you have. Then try the wiping between shots, etc. before looking for another bullet. Also, are you shooting fixed ammunition or breech-seating?

Don

If it were me, I'd go back to the old Ideal/Lyman 319247 bullet which runs somewhere in the 165 gr bullet when cast in a pure lead & tin alloy in the 30-1 to 25-1 range.  This is based on Winchester's original release for that barrel at that twist rate.

I would use one of the commercial lubes recommended for BP such as SPG.  Until I had a good baseline of data to work from, I would also wipe after every shot.   

Then I would probably get discouraged and go back to smokeless, but I hope YOU will have better luck and report back to us how well it works for you.   

Froggie

Mike,

     I have an old Lyman spitzer mould that throws a bullet of about 175-180 grains, and is called the French pattern after the name of the shooter who designed it.  I usually keep a few of these cast up in my standard 25-1 pure lead to tin alloy if you would like to try some out.  Contact me by PM if this would be of any help to you.

Froggie

I been looking at the photo and I can't see if there are any sign of the bullet  filling the groove dia.

Try seating a bullet, then fire a case with only a primer in it and  see if the case shoots out when you open the breech.

Just seems the bullet is to small of a dia to seal off the groove dia.

Never hurts to try.