ok let me try here
1 the only thing you will need to watch for accuracy is how accurate the gun is. They are great shooters. Just dont try to over load it. By that I mean 70 to 80 grains of powder will be plenty especially for a child.
2 you will need the 5/8 breech plug. The 7/8 as used up until I believe 2003 then changed to the 5/8. So anything coming from the factory now will be 5/8.
3 Blackhorn 209 is a substitute powder. It is very clean and is the closest thing to smokeless powder you can use in a muzzleloading barrel. It is tougher to ignite than black powder or other replicas such as pyrodex, triple 7, or shockey gold. A 209 primer is very hot in fact the recommendations are to use the hotter 209 primers with bh 209. A #11 cap or the 25 acp breech plug will not work with it. If you are not planning to use bh209, you can also consider the 25 acp breech plug which uses 25 acp brass which can have primers replaced in them. You have a choice of whch primers you use as small rifle and small pistol primers both work. It also eliminates a lot of the blow back into the action, as will the carrierless breech plug in this post. Good luck with the new barrel.
If it were I, I would get the 26 inch blued. It is only 2 more inches and will not make a great difference in the weight of the gun. Or you can look into having it shortened if you want.
