I bought my son a youth model Fox River Fifty almost 10 years ago from The Sportsman's Guide. They had .50 & .54 Youth and Adult models for $89 & $99 on closeout. The stocks they had available were a traditional brown hardwood and came with a brown plastic ramrod. I believe that these guns were what remained from the inventory of the original Gander Mountain Co. catalog. I've also seen others for sale in local shops and some with black stocks.
Our Youth model was overall a very reliable and fun plinking gun out to about 50 yards, and its 24" 1 in 48" twist barrel was fairly well made. The deep blueing on our lock and lock plate stayed very shiny and proved to be quite durable.
They are similiar to the current Traditions Deerhunter model but with about a 2 inch shorter barrel and an interesting sling stud screw method of attaching the barrel to the stock.
Because of the shorter barrel, these rifles are best suited for short ranges out to about 65 yards max. They also shoot somewhat more accurately if the powder loads are kept in the moderate range.
A good starting load for these rifles is 40-50 grains of powder by volume with a patched round ball (.490 for .50 caliber) and an .015 lubed patch at 50 yards. You can usually increase the powder charge slightly by 5 grain increments until you start to notice a decline in the accuracy if you intend to use it for hunting. You probably don't want to exceed 65-75 grains before you'll start to lose too much accuracy shooting a patched round ball. You can use more powder if you are shooting a conical or sabot, but the gun doesn't come with adjustable sights so you may need to compensate for the lower impact of the heavier projectile.
These are a very safe as well as a fun gun to shoot, and they are rated for up to 100 grains of ffg powder by volume, but you really don't need to shoot with that much powder, especially because they are sort of light in weight.
Enjoy it! My oldest son started out muzzle loading with this model when he was quite young, and enjoyed loading 30-35 grains of powder and shooting at 25 yards. Then we'd load 40-50 grains for target shooting at 50 yards. Loading it with a saboted conical and 80 grains of powder was an accurate load for 50 yards and beyond. We always shot Pyrodex in it, and it shot fine whether using the rifle ffg or pistol fffg granulation, but pistol powder volume can be reduced by 10% to be equivalent to ffg.