I've found at 25 yards, a patch of 6 pound denim (.013"by mic) will allow any of my rifles to shoot into an inch 1/2 or less, however the patches are burnt, black shrivels of cloth - when you can find them. Too, the bore picks up fouling that builds and soon it gets crunchy loading and would need wiping to continue. With 10 pound denim, I can shoot tighter groups yet at 25 yards and 50 yards - generally 4 out of 5 will be well inside 1" on centres, sometimes 5/8" for 4, but seem to allow myself to throw one out to make the group 1" to 1 1/2" sometimes more. Was that me or something else - don't know.
50 yards and farther, ie: 60 or 70 has proved much more reliable for working up a precise load than 25 yards. I've found most rifles will shoot into 1" or less at 25 yards, even some smoothbores I've benched do the same - what gives? At 25 yards, changing loads seems to make no difference in group size from .40 cal. on up. With even a .62 smoothbore punching one big hole for 5 shots at that range(& only one sight), there is no advantage to shooting a rifle. At 50 yards there is an advantage and of course, at longer ranges as well - however, the smoothie I shot at 50 yards & it was only one group, held 5 into 3". I've seen lots of guys do worse with rifles, which is why some smoothbore shooters do as well at close range gongs as do any rifle shooters. We have some of those at Hefley Creek Rondy - even at 100 yards, their scores exceed the rifle shooters - on gongs.
It's the scoring ring targets that separates the smoothbores from the rifles- sometimes.
When I work up a load for a rifle, it is at 50 yards - I pick a patch that when seating a ball into the rifling and pull it back out using the cloth as a handle, the ball is marked heavily with the cloth's weave by the bottom of the grooves. I know this patch will work & that the patch will clean the bore as it's loaded and shoot with the best possible accuracy from that bore. All I need to do is to find the load that is the most accurate, with THAT patch and ball. I use a ball that is .005" smaller than the bore - or larger as in the .40 cal. barrel. Over the years, I've found 10 pound denim to answer for all my patch needs - by my mic, it measures .020" for one brand and .0215" for another. This combination of ball size and patch thickness has worked well in every barrel I've ever shot, so is what I use in them all. The recent .58 Musketoon I acquired is the only anomaly to the "the load" as it uses a ball .011" smaller than the bore with the same .0215" patch in it's .003" rifling depth(at the muzzle).
Once I find the most accurate powder charge using an adjustable measure, I write it down so I don't forget.(got a lot of numbers floating around in my noggin and don't want to forget the best powder charge. Once I get home, I pour powder into the measure set at that mark, and weigh the charge - and write that down as the actual grains weight that barrel prefers. I'll make a measure of brass tubing (Hobby Store tubing) and scribe the tubing with the weight of powder it throws. That goes on a thong and is attacked to my shooting bag for that rifle. If I loose that measure, I can make another that throws the right amount in grains weight. If I didn't record the proper weight, I wouldn't be able to make a measure to throw the correct amount for that barrel.
I use the same amount of powder for every target, be it a 10 yard playing card on edge, little iron buffalo at 50 or the 92 yard(or thereabouts
) fox target. I never have to be concerned about fouling building up because with that ball/patch/lube combination, there is no buildup and the bore remains the same from the start of shooting to the finish.
The most accurate load is my target load and my hunting load, as it is usually a descent load, ie: 65gr. 3F in the .40, 70gr. 3F in the .45. My last .50 shot best with 100gr. 2F, my .58's, with 120gr. to 140gr.2F and the .69 with 82gr.3F for plinking to 50 yards and 165gr. 2F for shooting farther.
One thing to remember if you find your bore getting fouled, is that dumping in a light charge with a very wet spit patch then firing that, will effectively clean your bore.
Sometimes after shooting a long day on the trail, to reduce the fouling that is attached to the barrel's 'chamber' walls, I'll dump in 15 to 20gr. of powder along with a wet patched ball and fire that. Making sure the ball is on the powder is very important - with LHV or spit, loading down past where the ball was seated during shooting is easy as the '
wet' lube softens that fouling - I use the hole in the starter's head to help push the 'light' load down past the previous mark. sometimes a light smack with the hand's palm helps. This effectively cleans the bore right down almost to the plug and leaves only the fouling from the squib load in the bore itself. When cleaning after an 80 to 100 shot day, the water barely turns a light tinge of colour- not even grey. Cleaning the lock in the same water colours the can of water darker than cleaning the bore does.