My .40 Goodoien barrel, 7/8" x 42" had 48" twist. The grooves were very wide with quite narrow lands. I used a .398" ball with .0235" patch, or .225" patch, didn't seem to matter much. When I acquired a .400 Lyman DC mould, I found it cast one ball very badly WONKY, .394" x .400", while the other cavity cast .400" x .400". The .400's shot wonderfully, however the wonky ones didn't and made the mould a pain to cast with, so I went back to using the .398" mould.
I always used the heavy denim 10 OUNCE (.0225") patches or the mattress ticking that went .0235". Those were as I measured them, compressed hard in my calipers.
Accuracy was good with both water based WWWF lube as well as Lehigh Valley Lube or Hoppe's #9 PLUS. The water based lubes shot well with 55gr. 3F GOEX at 1,775fps.
The slippery lubes demanded more powder and speed. At 75gr. GOEX 3F, or 85gr. GOEX 2F, the accuracy was the same as the water based slower moving loads, yet both produced 2,240fps (might have been 2,270fps - my memory is giving me trouble on that).
By good, I am talking about small 1/2" C to C groups for 5 shots at 50 yards benched. I found I had to shoot at a 3" or 4" black circle, holding 6 o'clock to get those small groups. If I used a larger aiming point, my groups grew- but- that barrel was amazing, never shot over 1" with round balls and the thick patches. BTW - it was very easy loading and I could push the patch and ball into the bore with just the nub on my short starter, not needing to hit it with my hand. A very nicely rounded crown allowed this, yet did not hurt the accuracy.
edited to add the picture