The only true difference between modern in-line guns and traditional sidelocks is that in-lines use a rear-positioned primer for detonation, and sidelocks use a percussion cap or a pan, which ignites the powder charge from the side.

Black powder tends to foul more than most of the other options and it's corrosive, so you must clean a fired gun soon or risk damage. The federal government has classified black powder as a Class A Explosive and severely restricts its shipment, sale and storage. As a result, it's often very difficult to find. This is the largest reason the market has turned so hard to black-powder substitutes.

The first successful black-powder substitute was introduced in 1977 by Hodgdon. It is called Pyrodex, a term created by shortening "pyrotechnic deflagrating explosive." (You gotta believe that the guy who came up with that name was an explosives nerd). This propellant produces much less barrel fouling than black powder. Pyrodex (and all other current black-powder substitutes) are listed as a Flammable Solid by the government, so they can be handled and sold like smokeless powder. That means your local sporting goods store can sell it without special licenses, restrictions or complicated and expensive storage facilities. It's therefore much easier to get.

In most hunting rifles, RS or Select Pyrodex is the best choice. Pyrodex is designed to be used in the same volume as black powder. For example, if you are using 100 grains of black powder, you would keep your powder measure on exactly the same setting and use that volume of Pyrodex to produce an identical ballistic result.

Even with open sights, the accuracy of modern muzzleloaders is quite good.

In 1996 Hodgdon introduced Pyrodex Pellets, a solid form of Pyrodex that is matched to the performance of a given charge of loose powder. For example, two fifty-grain-equivalent pellets will give the same muzzle velocity as a 100-grain (by volume) charge of Select Pyrodex powder. The pellets are much easier to handle and are much faster during a reload. This makes them very attractive to a muzzleloader hunter. One end of a Pyrodex Pellet has a "secret formula" black ignition cap (actually black powder) that aids in lighting the pellet and should always face down, into the breech of the barrel. Hodgdon recommends Pyrodex Pellets be used only with in-line rifles and sabot bullets.

Hodgdon followed the success of Pyrodex in 2002 with a new black-powder substitute called Triple Seven. Triple Seven has more energy by volume than Pyrodex or black powder. So, using granular Triple Seven volume for volume with other substitutes or black powder will produce about a 15 percent increase in velocity per given charge. Triple Seven also creates less fouling and it cleans up with water. Because it's sulfur-free, there is no "rotten egg" smell, which results when other muzzleloader powders are being burned. Triple Seven granular powder is very accurate and has become the propellant of choice for some serious competition shooters as well as hunters. When testing new muzzleloaders for accuracy, I often find that Triple Seven FFg is the most accurate substitute propellant.

In 2003 Hodgdon introduced Triple Seven Pellets, which are formulated to deliver the same energy equivalent as black powder or Pyrodex. For example, a "fifty-grain" Triple Seven pellet produces the same energy as fifty grains by weight of black powder or fifty grains by volume of Pyrodex. This year Hodgdon announced its new Triple Seven Magnums Pellets. These are formulated to give the performance of three-pellet "magnum" muzzleloader loads with just two pellets. Magnums are designed for use only in .50-caliber in-line muzzleloaders with No. 209 primers for ignition.