A .22 LR MP5 is legal to own in California, and factory-compliant models sit on dealer shelves without any aftermarket work. California’s assault weapon statute reaches semiautomatic centerfire rifles, so the rimfire MP5 sidesteps the feature bans that would flag its 9mm sibling. You still have to clear barrel and overall length minimums, stay at or under a 10-round magazine, pass the standard background check, and wait 10 days before pickup. The total state fee is $37.19.
Why the Rimfire Version Is Legal
Penal Code 30515 defines an “assault weapon,” and every rifle category in that statute is limited to a “semiautomatic, centerfire rifle.” A centerfire semiautomatic with a detachable magazine and any one listed feature qualifies. Those features include a protruding pistol grip, thumbhole stock, folding or telescoping stock, flash suppressor, and forward pistol grip.1California Legislative Information. California Penal Code PEN 30515
The .22 LR MP5 fires rimfire ammunition. Because the rifle provisions of the statute don’t reach rimfire actions, a rimfire semiautomatic rifle can carry a pistol grip, a telescoping stock, and a detachable magazine at the same time. That is why the rimfire MP5 keeps its recognizable profile in California while a 9mm MP5 clone would be classified as an assault weapon.
The exemption is narrow. It only clears the feature test. Every other California firearms rule still applies: magazine capacity, minimum length, the dealer transfer, the background check, and the waiting period.
Barrel and Overall Length
Penal Code 17170 defines a short-barreled rifle as any rifle with a barrel under 16 inches or an overall length under 26 inches. Both numbers have to be cleared, or the firearm is prohibited.2California Legislative Information. California Penal Code PEN 17170 – Short-Barreled Rifle
Most .22 LR MP5 models meet the 16-inch barrel minimum by permanently attaching a faux suppressor to a shorter barrel. The faux suppressor is cosmetic and does no sound reduction. It’s pinned or welded so it forms a single unit with the barrel. California-compliant models typically ship this way, with the faux suppressor and a 10-round magazine already installed.
Overall length gets measured with a collapsible stock in its shortest functional position.3Cornell Law School. 11 CCR 5471 – Registration of Assault Weapons Pursuant to Penal Code Section 30900 If your model has a stock pinned in the extended position, the pinned length is what counts, because the stock can no longer collapse. If it isn’t pinned, measurement happens at the shortest setting. Either way, you need to hit 26 inches.
Possessing a short-barreled rifle is charged under Penal Code 33215, which can be filed as a misdemeanor with up to a year in county jail or as a felony.4California Legislative Information. California Penal Code PEN 33215 Buying a factory California-compliant model removes that risk.
Magazine Capacity
The rimfire exemption does not carry over to magazines. Penal Code 32310 prohibits manufacturing, importing, selling, giving, or lending any magazine that holds more than 10 rounds, regardless of caliber.5California Legislative Information. California Penal Code PEN 32310 The .22 LR MP5 ships with 25-round magazines in most states. California versions come with 10-rounders.
Some dealers stock “blocked” magazines built on the 25-round body with a permanent insert that caps them at 10. Those are legal only if the block is truly permanent and the magazine cannot accept more than 10 rounds under normal use. If you’re buying used or bringing something in from out of state, verifying capacity is on you.
Possession of any magazine over 10 rounds is separately prohibited under the same statute, with penalties ranging from an infraction with a fine up to $100 per magazine to a misdemeanor carrying up to a year in county jail. Federal litigation on the possession ban is currently before the U.S. Supreme Court. Until it’s resolved, treat the 10-round limit as fully enforceable.
One point of confusion worth clearing up: California exempts .22 caliber tube feeding devices from the large-capacity magazine definition. That applies to tubular magazines built into lever-action rifles, not to the detachable box magazines the MP5 uses. The 10-round cap applies to the MP5 magazine.
Age and the 30-Day Purchase Limit
California generally requires you to be at least 21 to buy any firearm from a licensed dealer. The rimfire distinction opens a door for younger buyers.
Penal Code 27510 restricts sales to under-21 buyers specifically for handguns and semiautomatic centerfire rifles. A semiautomatic rimfire rifle falls outside that language.6California Legislative Information. California Penal Code PEN 27510 An 18-year-old holding a valid California hunting license can legally buy a .22 LR MP5. Active-duty military, honorably discharged veterans, and active peace officers aged 18 or older also qualify. Without one of those credentials, the minimum is 21.
California also limits buyers to one handgun or one semiautomatic centerfire rifle per 30-day period.7Office of the Attorney General. Overview of Key California Firearms Laws The rimfire MP5 doesn’t count toward that limit, so you could pick one up alongside another rimfire rifle in the same window.
What to Bring to the Dealer
Have these ready before you head in:
- California driver’s license or state ID. If the front reads “FEDERAL LIMITS APPLY,” also bring proof of lawful U.S. presence, such as a valid passport, certified birth certificate, or permanent resident card.8New York Codes, Rules and Regulations. 11 CCR 4045.1 – Additional Documentation Requirements for Eligibility Checks with Federal Non-Compliant California Driver License or Identification Card
- Firearm Safety Certificate. You earn it by passing a written test at any licensed dealer, with a $25 fee, a 75% passing score, and a five-year validity. Most dealers can give the test on the spot, so build in extra time if you don’t already hold one.9Office of the Attorney General. Firearms Safety Certificate Study Guide
- Proof of California residency. For long guns, a second document confirming your address is typically required alongside your ID. A utility bill, vehicle registration, or residential lease works.
Fees, Background Check, and the 10-Day Wait
Once you pick your MP5 and hand over your documents, the dealer enters the sale into the Dealer Record of Sale (DROS) system, which transmits your information to the California Department of Justice for the background check.10Office of the Attorney General. Firearms Dealers
The state fees total $37.19:
- $31.19 DROS fee, covering the background check and transfer registry
- $5.00 Safety and Enforcement Fee
- $1.00 Firearms Safety Act Fee
Those are state fees only.11Office of the Attorney General. Frequently Asked Questions The dealer will add sales tax on the firearm’s price and often a handling fee. Budget for the sticker price plus roughly 10-15% in combined fees and taxes.
The 10-day waiting period starts when DROS is accepted. You can’t pick up the firearm before those 10 days run, even if your background check clears in hours. When you come back, two things happen before you walk out with it.
You perform a safe handling demonstration using a dummy round. For a semiautomatic long gun, that means verifying the chamber is clear, loading and chambering a round, clearing it, and engaging the safety, all while keeping proper muzzle awareness and trigger discipline. The dealer walks you through the steps and it takes only a few minutes.12Cornell Law School. 11 CCR 4257 – Safe Handling Demonstration Steps for Conventional Long Guns
The firearm also has to leave the store with a California DOJ-approved safety device, such as a cable or trigger lock.13Office of the Attorney General. Roster of Firearm Safety Devices Certified for Sale Most compliant models include one in the box. If yours doesn’t, the dealer will sell you one at the counter.
Buying .22 LR Ammunition
California runs a point-of-sale background check on every ammunition purchase, .22 LR included. You show ID at the vendor and the store submits your information to the DOJ electronically.14Office of the Attorney General. Ammunition Purchase Authorization Program Speed and cost depend on your history in the state’s system.
If you’ve bought a firearm in California and your current ID matches that record in the Automated Firearms System, the check is quick and inexpensive. If you don’t have a matching record or a current Certificate of Eligibility, the DOJ runs a more thorough review that can take several days. Buying ammo on the way to the range isn’t always a walk-in-walk-out experience, so plan ahead.
One shortcut helps here. If you buy ammunition at the same time and from the same dealer as the firearm, the dealer can use the approved DROS check to authorize the ammunition sale in the same transaction. Pick up a few boxes of .22 LR when you collect the MP5 and you skip a separate ammo background check entirely.