Greenrivers, Regarding peep sights. ...I've been down that road trying to make-do with aging eyes. Well, ...still on it I guess. I have about past the peep sight stage and approaching scopes only. Anyhow, you are on the right track. A good peep sight will help a lot.
My favorite peep is a Lyman 57. It is basically a receiver sight with a base that attaches to the tang. I have had one on a T/C Hawkens for nearly 40 years. It looks a little fragile sitting up there but I am careful with it and, so far, have had zero problems. I generally sight in with a medium or large aperture and hunt with the aperture removed. I have looked at the Lyman web site and they no longer list this sight but it looks like they are using it or something similar on their Great Plains Rifle. There's probably some used ones floating around somewhere. It would be worth looking for.
I have one of the T/C tang peep sights on another ML. It is a serviceable sight but not so easy to adjust as the Lyman and the aperture is non-standard, limiting you to what T/C supplies. I drilled mine out as far as possible and it works OK.
I have not used one but Skinner Sights (
http://www.skinnersights.com/index.html) makes a peep sight you may be interested in. It mounts on the barrel and not the tang but it looks rugged and they have a variety of apertures available.
By the way, for those not familiar with using peep sights. A small aperture is great for shooting in good light but, in dim light, you may not be able to see through the aperture AT ALL. It can look like a solid disk with maybe a light grey spot in the middle. It has to do with your pupil dilating larger than the aperture.
With regard to projectiles, ...I have never used a .54 ML, only .45s & .50s, so can only offer general observations. I cast my own T/C maxiballs for many years and they were always accurate and reliable. Best accuracy seemed to come with maximum loads of real black powder.
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I Googled around a bit and Track of the Wolf has the Lyman sight here...
http://www.trackofthewolf.com/categories/partdetail.aspx?catid=14&subid=167&styleid=770&partnum=rs-57-sml&as=1 Content edited, please read the sticky on what can't be discussed in this forum. quickdtoo OOPS !!! My sincerest apologies. I just got rambling along and did not realize that discussing sabots was forbidden. I'll pay more attention in the future. I hope I have not offended anyone.