The Rimfire Loophole:
Why Your 10/22 Isn't an Assault Weapon

Can I put a pistol grip stock on my Ruger 10/22 in California?

The Centerfire Limitation

California Penal Code Section 30515(a)(1)^[1] defines "assault weapon" in relevant part as a "semiautomatic, centerfire rifle" that does not have a fixed magazine and has any of the enumerated features (pistol grip, thumbhole stock, folding/telescoping stock, grenade/flare launcher, flash suppressor, forward pistol grip). The word "centerfire" is a critical limitation.

A semiautomatic rimfire rifle, such as the ubiquitous Ruger 10/22 (.22 LR), is not covered by the features test. This means a 10/22 with a detachable magazine, pistol grip stock, folding stock, and a flash suppressor is not an assault weapon under Section 30515(a)(1). This is not a loophole discovered by creative lawyers; the legislature deliberately limited the features test to centerfire rifles.

Important Limitations

The named-model ban still applies. Penal Code Section 30510^[2] incorporates the Roberti-Roos list by reference. If a specific rimfire model is listed by name (as certain configurations of the Feather AT-22, Calico M-100, and others are), it remains a prohibited assault weapon regardless of caliber. The Ruger 10/22 is not on the Roberti-Roos named list.

Large-capacity magazine restrictions apply independently. Penal Code Section 32310 prohibits possession of magazines capable of holding more than 10 rounds regardless of the type of firearm they fit. A 25-round Ruger BX-25 magazine is restricted under Section 32310 even though the rifle it fits is not an assault weapon. (Subject to ongoing Duncan v. Bonta litigation and Freedom Week acquisition arguments.)

Semiautomatic centerfire pistols and shotguns have their own rules. Section 30515(a)(4) covers semiautomatic pistols (no centerfire limitation for pistols with fixed magazines under 10 rounds and certain features), and Section 30515(a)(7) covers semiautomatic shotguns. The rimfire gap applies specifically to the rifle features test.

Why This Matters

The rimfire exemption has practical significance for several popular platforms:

The Ruger 10/22 can be configured with virtually any stock, including AR-15-style chassis systems with pistol grips and telescoping stocks, and remain legal (with a 10-round magazine). The Smith & Wesson M&P 15-22 (.22 LR), which closely resembles an AR-15, is not an assault weapon despite having a pistol grip and detachable magazine because it is rimfire. The Kel-Tec CP33 (.22 WMR rimfire pistol) with its 33-round magazine would be restricted only by the magazine capacity limit, not the assault weapon features test.

Legislative Risk

Bills have been introduced in past legislative sessions to remove the "centerfire" limitation from Section 30515(a)(1), which would extend the features test to rimfire rifles. None have passed. The legislature's failure to close this gap despite multiple attempts suggests either deliberate policy (rimfire calibers are considered less dangerous) or insufficient political priority.

Bottom Line

Settled: The features test in Section 30515(a)(1) applies only to semiautomatic centerfire rifles. Rimfire rifles may have any combination of features without triggering assault weapon classification under this subsection.

Unsettled: Whether the legislature will extend the features test to rimfire in future sessions. Whether certain rimfire platforms configured to closely resemble centerfire assault weapons could be challenged under other legal theories.

Do: Before configuring a rimfire rifle with features, verify that the specific model is not on the Roberti-Roos named list (Section 30510). Use only 10-round or smaller magazines unless you have a valid Freedom Week claim.