The long range muzzle loading rifle is a specialty of its own and has components that are not found on any other type of muzzle loader.
The most important of these is the breech plug. It is made to withstand 100 grains of high quality BLACK POWDER lighting up and moving a bullet of 480 grains minimum and more likely 500 to 550 grains either lubricated or paper patched. The pressures that develop in long range rifles firing elongated bullets are higher by far than any round ball rifle.
If the barrel has a drum and nipple screwed into the side (example pictured right) it would be positively dangerous to use. The drum would eventually blow out and a tragedy could occur if the fellow shooting next to you was hit by this oddly shaped part. One such load could be sufficient to blow a drum off the side of a barrel.
Most breeches today are made for round ball barrels which work at far lower pressures than the muzzle loading match rifle. The breech must be designed in such a way so as to minimise pressure on the base of the nipple. Just because a barrel has a "patent breech" or bolster instead of a drum and nipple does NOT make it completely suitable for a muzzle loader firing a long, heavy projectile. The breech MUST BE DESIGNED with this application in mind.
The end result of bad "patent breech" design can result in blown out nipples and broken lock tumblers because the full pressure of the load was on the base of the nipple with that little 1/4x28 thread. The breech MUST be designed so as to eliminate as far as possible, this condition.
Pictured right is an original Whitworth match rifle designed for long range target shooting.