Well, they all shoot high out of the box. If yours is used, I suspect the person who owned it previously never replaced the issue front sight.
Replacing the front sight with a taller and thicker one, will lower the point of impact, and if the gun isn't shooting more than an inch or so left, you can file the width of the sight to correct the point of impact. Looking up the barrel from the rear sight towards the front sight, file the front sight in the direction you want the bullet to move. In other words file the
right side of the thicker front sight(the lock side.) to move the point of impact right. Somepeople are confused by this, since they have correctly heard that you move the front sight in the direction OPPOSITE the desired point of impact. Since your sight is soldered on, and can't be drifted (unless you want to dovetail the front sight) you must file the sight in the direction you want the bullet to move to.
If you are shooting anything less than a one hole group off a bench at 50 yards, the accuracy can be greatly improved with glass bedding. The inletting on these guns is average to poor, and the breech of the gun has room to move.
I just bedded a musketoon on Sunday, and they are an easy job. I used Accraglass and recommend it highly. Be sure you coat all metal parts with the realease agent, including the lock plate. I'm told the release agent is bad for springs, so just coat the plate with several thin applications. You don't need to disassemble the lock, just coat the edges and interior surfaces of the plate. Make sure you apply several coats of release agent to the tang and breech, lock screws and tang bolt. Also coat the inside and edges of the bands.
Follow the mixing instructions exactly. A single cup of hardener and resin is more than enough compound to bed a musketoon. Be sure to tape the flat top edges of the stock, because once you place the barrel in the channel, and affix the bands and tighten them in position, the compound will squeeze out of the channel and onto the stock. While it can be cleaned off with vinegar, it is much easier just to have it ooze out onto the tape. Back off the ramrod spoon two inches in both directions so that the compound doesn't ooze onto it. Make sure you locate the bands in the correct positions. The flat shoulder of the bands rest against the flat of the stock, and the band screws heads should be on the lock bolt (left side) of the gun. Make sure you can withdraw the ramrod, before letting the compound set up. If the bands are too tight, you wont be able to pull the ramrod.If you have to loosen the bands after the compound dries, you defeated the purpose of bedding which was to insure full barrel contact in the stock channel.
Properly tuned these guns are amazingly accurate. The position of the rear sight is a little too near the shooters eye to give as good a sight picture as can be obtained with the 1858 naval pattern, but the sights are still quite good.
Get the gun to shoot spot on at 50 with the rear sight fully depressed. "Kick it up a notch" to have it shoot on at 100. I've won a lot of matches with musketoons and have taken a number of deer with a variety of Enfields. You'll never have to track a deer that's been hit by a minie. They go right down. If you practice with the musketoon until you can consistently shoot in the mid to upper 40's at 50 yards, and low to mid forties at 100, you will be the end of any deer you meet. The guns are very accurate for 200 yard offhand shooting as well. I should mention however that all rifle muskets have trajectories like a rainbow, and if you aren't an excellent judge of distance 10 ring accuracy at 200 yards will translate into a clean miss at 225.
If you haven't already done so, I'd pick up a cartridge box and preload some ammo. Besides offering oustanding accuracy (with the right sized bullet) they are easy and fast to load. You don't have to worry about patches and short starters like you do with round balls. The bullet should be able to be placed in the barrel with your thumb and index finger. No presure is needed.
The bullet should NOT drop down the barrel, but should require light pressure with the ramrod.
A bullet sized to .575 works very well in these guns. I know some people who prefer to size them to .576, but I'm happy with the results from a .575 diameter minie.
I should mention that if you intend to use the rifle for hunting, fire a squib prior to taking to the woods. The bullet depends on fouling for a good fit. The 1st shot is rarely as accurate as the second, and a lubricated bullet in an un-fouled barrel can "walk" on you.
If there is an N-SSA outfit in your region, check out a skirmish. It might interest you, but even if you don't join, you'll receive some excellent information on the care, cleaning and "accurizing" of muskets.
I don't know of another muzzleloading shooting organization with 5,000 competitiors. I've never been to a round ball match that had more than 100 participants and most local shoots are lucky mto draw 25 competitors. 200 competitors at a local skirmish is common. There are many knowledgeable and excellent shooters out there, and the N-SSA has been promoting competition for over 55 years.
Rather than re-invent the wheel, talk to a wheelwright.