Washington. The primer/precussion cap, has to be exposed to the elements. No 209 shotshell primers allowed uless it fits like a precussion cap and es exposed. You must choose muzzeloader when you buy your tag, and you can only hunt for that animal in muzzelloading seasons. For deer it must be 45 caliber or larger, other big game is at least 50. No pistols allowed for hunting. No other firearm may be in your possetion except for muzzelloader. You may have more than one barrel but during muzzelloading seasons you may only have one barrel loaded. No copper jacket bullets. No scope or optics. Fiber optic open sights are ok. I think thats about it.
Season is significatly longer than modern firearm. But a little shorter than archery. It overlaps archery often. The early and late seasons for deer are each like 3 weeks I beleive.