http://www.eregulations.com/california/hunting/mammal/general-big-game-regulations/
https://www.wildlife.ca.gov/Hunting...he-nonlead-ammunition-regulation-take-effect-
https://www.wildlife.ca.gov/Hunting/Nonlead-Ammunition/Certified
During the California Muzzleloader Hunting Season – Wheel-lock, matchlock, flintlock or percussion type, including in-line muzzleloading rifles using black powder or equivalent black powder substitute, including pellets, with a single projectile loaded from the muzzle and at least .40 caliber in designation. A projectile is defined as any bullet, ball, sabot, slug, buckshot or other device, which is expelled from a firearm through a barrel by force. Under the provisions of a muzzleloading rifle only tag, hunters may only possess muzzleloading rifles as described in subsection, equipped with open or peep type sights only.
Only legal muzzleloaders allowed in muzzleloading seasons.
b. In-line muzzleloaders are legal.
c. Must be single-barrel that fires a single round-ball or conical projectile.
d. To hunt deer, pronghorn or bear, they must be minimum of a .40 caliber.
e. To hunt elk or moose, they must be minimum of a .50 caliber.
f. From a .40 caliber to a .50 caliber, bullets must weigh minimum 170 grains.
g. If greater than a .50 caliber, bullets must weigh minimum 210 grains.
h. Shotshell primers are legal.
Only open or iron sights allowed in muzzleloading seasons. Fiber optics and fluorescent paint incorporated into or on open or iron sights are legal. Scopes or any sighting device using artificial light, batteries and electronic gear are prohibited during muzzleloading seasons.
l. Sabots are prohibited in muzzleloading seasons. Cloth patches are not sabots.
m. Smokeless powder prohibited in muzzleloading seasons. Black powder and black-powder substitutes are legal.
n. Electronic or battery-powered devices cannot be incorporated into or attached to muzzleloader during muzzleloading seasons. ***During California Muzzleloader Hunting Season, Muzzleloading projectiles must be certified California legal. This includes Barnes T-EZ & T-MZ, Hornady GMX/MonFlex, and Thor bullets.***
So
No lead projectiles starting July 1 2019 anywhere in Cali.
No scopes
No smokeless
209 primers are legal
Sabots and pellets may depend on the season. Its a bit confusing. Check with your local authorities. Some specific hunts might have more restrictions than statewide regs
40cal minimum for deer, bear and pronghorn 170gr minimum bullet weight
50cal minimum for elk and moose...210gr minimum bullet weight for larger than 50cal.
I see no restriction on the kind of action. Bolt vs break action or Omega type (falling breach) doesn't matter. Single barrel is the only action oriented requirement. All are legal so its personal preference.