To compete "officially" I've posted the rules below.
That being said, we're a pretty laid back bunch of Marksmen. If you want to try it with a different type of rifle you may. You just can't "win".
Also, Ridgway goes out to 1000 yds if you want to try your hand at that. There's a buffalo silhouette @ 980 yds. I've hit it with a muzzle loader.
3.4 Black Powder Cartridge Rifle - A hunting or military style rifle, single shot, originally made for black powder cartridges, of United States manufacture prior to 1896 and being typical of the era. Replicas thereof, regardless of origin of manufacture, are permitted. Hammer must be exposed. If replacement barrels, stocks, or other parts are used, they must be as original. No Schuetzen-style rifles permitted. One rifle will be used during all phases of the match. Examples of permissible rifles are: Ballard, Buck, Bullard, Cole, Farrow, Maynard, Peabody, Redfield, Remington Hepburn, Remington Rolling Block, Sharps, Springfield Trapdoor, Stevens Tip-up, Stevens No. 44, Wesson Falling Block, Wesson (hinged barrel), Whitney Phoenix, Whitney Rolling Block, Winchester 1885, and Wurfflein. While the following single shot actions may not conform to the exact criteria of Rule 3.4, they are allowed because they conform to the spirit of the competition in forth and function, provided the firearms conform to all other configurations of Rule 3.4: Browning Model 1878, Browning Model 1885, C. Sharps '75, Falling Block Works, Stevens 44 1/2 and Wickliff '76. Replicas other than exact reproductions of pre-1896 Black Powder actions as described above and shooting equipment as described herein, must be passed by the Silhouette Committee with the advice of the Black Powder Committee. It shall be the competitor's responsibility to provide any documentation which may be required to establish that all Black Powder Cartridge Rifle equipment conforms to these rules.
(a) Maximum weight 12 pounds, 2 ounces.
(b) Rear sights will be of vernier or ladder type, typical of the era, either open or peep, mounted on the tang or barrel. No modern style receiver, glass, or tube sight permitted. Front sights must be typical of the era, and may be shaded. No modern or olympic-type sights permitted.
(c) Trigger typical to the rifle and not subject to accidental discharge.
(d) Cartridges will be of the American black powder era, originally black powder loaded, manufactured prior to 1896, and originally chambered in American-manufactured rifles, taking into account normal variations in types of brass and primers, as well as bore sizes, rifling styles, twist and chamber dimensions. Cartridges must be loaded with black powder or Pyrodex only. No smokeless powder in any quantity may be used. Match officials, at their discretion, may select one or more loaded cartridges at random, pull bullet, and check contents. Competitors will furnish their own ammunition.
(e) Cast or swaged lead or lead alloy projectiles only; no jacketed or gas checked bullets. Paper patching permitted. Breech seating is permitted but no additional time will be allowed.
(f) Stock: Forearm must be attached and shall be of traditional design not to exceed 2 inches in width, cannot extend below the line of the bottom of the receiver or base of trigger guard, and no attachments will be allowed on the forearm. Measured froth the centerline of the bore, the drop at the heel shall not exceed 2 3/4 inches; drop at toe shall not exceed 8 inches. No portion of the rifle stock behind the rifle action shall be higher than 3/4 inch below the centerline of the bore. The butt shall not be longer than 5 1/4 inches top to bottom. Cheek pieces are permitted, but no roll over. Pistol grips are permissible, but no flared or hand-contoured styles. Crescent-style buttplates are permissible, but cannot be over 1 1/8 inch deep when measured froth a straight line from points of the buttplate. Commercial recoil pads are permissible. Stocks and forearms must be made of natural wood and must be in keeping with designs of stocks of the era. (See Rule 3.18.)
(g) No slings are permitted.
3.4.1 Scoped Black Powder Cartridge Rifle - Identical to the description of the BPCR (Rule 3.4) with the following exceptions:
(a) Maximum weight with scope - 15 pounds
(b) No length or power limitation on the scope. Scope tube body to be 3/4" or less in diameter and any ocular or objective lenses, adjusting or assembly rings to be less than 1" in diameter.
(c) No internal scope adjustments for windage or elevation.
(d) Mounts to be of the traditional Malcolm style of the period with yoke and vernier on the side, with no click adjustments or turret knobs, and contain the windage and elevation adjustments for the scope in either, or both, the front or rear mounts. Either dove tail mounting or scope block mounting is allowed.
(e) Add-on cheek pieces are not permitted.
5. POSITIONS
5.2.1 Artificial Support for Black Powder Cartridge Rifle - Artificial support for Black Powder Cartridge Rifle only shall be in the form of approved design crossed sticks constructed of two wooden legs, no greater than 1 inch by 2 inches in thickness and width or 1 1/2 inches in diameter, and bolted or tied so that the two legs are hinged and capable of pivoting. The end of the legs may be equipped with spikes no more than 3 inches in length and no wider than the edge of the crossed stick. They may be inserted into the ground by hand pressure only to aid in retention of an upright position. This may be waived by the Match Director to fit local conditions. One layer of protective material may be suspended or inserted in the "V" of the crossed sticks to protect the rifle. All cross sticks will be certified.
5.8.1 Firing Position, Black Powder Cartridge Rifle - 200 meters - Any standing position without artificial support. The rifle will be supported by the hands and one shoulder. All parts of one hand must be forward of the pistol grip.
300, 385 and 500 meters - Any position, including crossed sticks, but excluding bench rest.
(a) A "crossed stick" position is one where the shooter is in a prone, sitting, kneeling or standing position with the barrel or forearm resting in or above the "V" of the crossed sticks in such a manner that no competitor or range personnel are endangered. See 5.2.1.
7. COURSES OF FIRE
The following course and type of fire is most commonly found in NRA-sanctioned BPCR competition, fired on standard silhouette targets.
7.1 Black Powder Cartridge Rifle Competition - A sanctioned match consists of 40, 60, 80 or 120 rounds fired in the appropriate positions in Black Powder Cartridge Rifle (see 5.2.1) as follows (an example of the minimum course of fire):
(a) Ten Gallina (chicken) targets at 200 meters (or yards).
(b) Ten Javelina (pig) targets at 300 meters (or yards).
(c) Ten Guajalote (turkey) targets at 385 meters (or yards).
(d) Ten Borrego (ram) targets at 500 meters (or yards).