AOW Classifications: Short-Barreled Shotguns, Pen Guns, and Trust Placement

The Any Other Weapon (AOW) category in the National Firearms Act is the regulatory framework's miscellaneous bin — a category that sweeps up devices that don't fit neatly into suppressors, short-barreled rifles, short-barreled shotguns, or machine guns, but that federal law nonetheless wants to regulate. AOWs include pen guns, cane guns, smooth-bore pistols of certain configurations, and a variety of other specialty items that fall outside the primary NFA categories.

For collectors, AOWs are interesting for several reasons. The regulatory framework is slightly different from other NFA categories — most notably, the transfer tax is $5 rather than $200, a distinction that matters meaningfully for some collecting strategies. The item population is diverse and includes some historically significant pieces. And the trust placement decisions for AOWs can have real consequences for collection management, particularly for collectors who mix AOWs with other NFA categories.

This piece walks through the AOW framework, the specific item types that fall within it, the regulatory peculiarities collectors should know, and the considerations that affect how AOWs should be held in an NFA trust.

What AOW Actually Means

The AOW definition in federal law is 26 U.S.C. § 5845(e), which describes "any weapon or device capable of being concealed on the person from which a shot can be discharged through the energy of an explosive." This broad definition then gets more specific, covering pistols with smooth-bore barrels designed for firing shotshells, firearms with combinations of rifle and shotgun barrels below specified lengths, and weapons disguised as other objects.

What the definition does not cover is a normal pistol, which is regulated under the Gun Control Act but is not an NFA item. The AOW category is specifically for weapons that have unusual characteristics — concealment, disguise, alternative firing mechanisms — that place them in the NFA framework despite not being suppressors, SBRs, SBSs, or machine guns.

This creates sometimes surprising classifications. A short-barreled shotgun with a pistol grip and no shoulder stock, for instance, is classified as an AOW rather than as an SBS, even though it might look similar to a more conventional SBS. The specific combination of features determines the category, and collectors sometimes find that items they thought were one category are actually another.

Specific AOW Item Types

Several categories of items fall under AOW classification:

Pen Guns and Similar Concealed Firearms

Single-shot firearms built into pens, keychains, and similar concealing items are AOWs. These are rare in civilian collections but do exist. Most were manufactured decades ago (modern production is limited by practical and regulatory factors), and surviving examples are collector pieces with historical interest.

Cane Guns

Firearms concealed in walking canes are AOWs. Historical examples from the 19th and early 20th centuries are collector pieces; a few contemporary manufacturers have produced cane guns for collectors interested in the category.

Smooth-Bore Handguns

A smooth-bore pistol — meaning a pistol with a barrel that lacks rifling — is an AOW if it's designed to fire shotshells rather than standard pistol ammunition. The H&R Handy-Gun, manufactured between the wars, is the classic example; surviving examples are collected.

Short-Barreled Shotguns in Pistol Configuration

A shotgun-style firearm with a barrel under 18 inches but equipped with a pistol grip and no shoulder stock is classified as an AOW rather than as an SBS. These are sometimes called "firearms" in manufacturer literature but are AOWs under federal law when they meet the specific definitional criteria.

Certain Combination Guns

Firearms with combinations of rifle and shotgun barrels that fall below specified length thresholds may be AOWs. These are rare items, generally of historical interest.

Disguised Firearms Generally

Any firearm disguised as another object — a flashlight, a belt buckle, a briefcase — falls into the AOW category. The category is intentionally broad to cover the variety of concealment approaches that would otherwise escape NFA classification.

The $5 Transfer Tax Distinction

The most distinctive regulatory feature of AOWs is the transfer tax structure. For most NFA items, transfers pay a $200 tax stamp. For AOWs, the transfer tax on civilian-to-civilian transfers is $5 — meaningfully lower than the other NFA categories.

This lower tax reflects the historical policy decision that AOWs, while requiring regulation, represented a less severe policy concern than machine guns and shotguns with shoulder stocks. The $5 rate has been in place since the National Firearms Act's original structure and has not been updated for inflation.

For collectors, the lower tax makes AOW acquisitions less expensive per transaction than equivalent SBR or suppressor acquisitions. This does not usually drive collecting strategy in itself — collectors acquire items they want to own, not items with low transfer costs — but it does mean that AOW-heavy collections have lower accumulated tax cost than other NFA categories of equivalent item count.

Note that the $5 rate applies only to transfers. The $200 rate applies to manufacturing (Form 1) for AOWs as for other NFA categories. An applicant who manufactures an AOW from a previously unregistered item pays the standard $200 making tax.

Trust Placement Considerations for AOWs

AOWs can be held in an NFA trust alongside other NFA categories with relatively few complications. However, specific considerations apply.

Same Trust or Separate Trust?

Collectors sometimes wonder whether AOWs warrant a separate trust from the rest of their NFA collection. Legally, the same trust can hold AOWs alongside other NFA categories — there's no regulatory reason to separate them.

Operationally, separate trusts can make sense in specific situations. If the collector has very different beneficiary intent for AOWs than for other items (perhaps the AOWs are destined for a museum donation while other items are for family heirs), separate trusts simplify the operational planning. If the collector has complex gifting strategies involving AOWs specifically, separate trusts may create useful flexibility. For most collectors, these considerations don't apply, and a single trust holding everything is simpler.

Schedule A Treatment

AOWs should be listed on the trust's Schedule A alongside other NFA items. Schedule A is the inventory attachment to the trust document; maintaining accurate Schedule A is important for all items, including AOWs.

The description of AOWs on Schedule A deserves some care. The specific category classification (which AOW subcategory the item falls under) should be noted, not just a generic description. This clarity helps during applications, audits, and succession events.

Identification and Documentation

AOWs often have unusual features that affect identification. A pen gun's appearance as a pen rather than as a firearm means that the item's registered description must be more detailed than it would be for an ordinary handgun. Serial numbers, manufacturer, distinctive features, and any marks should be documented carefully.

Photographs of AOWs for insurance and inventory documentation are particularly important because the items' appearance may not match what someone unfamiliar with AOWs would expect. A policeman examining the collection in a crisis, for instance, may not immediately recognize a pen gun as a firearm, and photographs with clear identification help establish the item's status.

Storage and Handling

AOWs should be stored securely like other NFA items. The concealment nature of some AOWs creates specific risks — a pen gun kept casually in a desk drawer might be mistaken for an ordinary pen by a family member or visitor, leading to accidents or unauthorized handling. Secure storage away from everyday contexts prevents these risks.

Handling AOWs requires the same regulatory awareness as other NFA items. Responsible persons in the trust can handle them; non-trustees cannot, regardless of how ordinary the item might appear. Trust holders should be aware that the casual nature of some AOWs (a pen or cane that looks unremarkable) can make it easy to forget that regulatory restrictions apply.

AOWs in Estate Planning

AOWs in an estate follow the same Form 5 transfer procedures as other NFA items. Heirs receive their designated items through tax-free transfer (or $5 transfer for AOWs that pass outside the tax-free provisions). The beneficiary provisions for AOWs should be specific enough to avoid ambiguity about who receives them.

Some AOWs have distinctive value to collectors — a pristine H&R Handy-Gun, for instance, may be worth significantly more than a generic firearm of similar vintage. Estate planning should account for the value differences between AOWs, particularly when multiple heirs are receiving different items. A clear valuation at the time of the grantor's death helps establish a fair distribution and provides the basis for any estate tax calculations.

AOWs intended for museum donation require specific planning. Museums typically cannot accept NFA items without specific compliance procedures (often requiring the museum to have its own regulatory compliance or to work with an intermediary). Grantors who intend museum donation should work with their attorney to establish a clear path for such donations rather than assuming the standard estate procedures will handle them.

AOWs and Collectors' Specific Interests

The AOW category attracts collectors with specific interests. Some are historical-piece collectors for whom the mid-20th-century concealment designs are genuinely interesting as artifacts. Some are collectors of unusual firearms generally, for whom AOWs represent a distinct sub-specialty. Some are accidental AOW owners — acquiring items that they didn't realize were AOWs until they encountered the classification during compliance work.

For collectors approaching AOWs deliberately, the market has some distinctive features. Auction prices for historical AOWs have appreciated substantially over the last several decades, particularly for well-preserved examples with good provenance. The item population is small, and demand from specialty collectors keeps prices above what comparable non-NFA items might command. This creates investment dynamics for AOWs that some collectors find interesting.

For collectors who find AOWs outside their interests, the items can be held passively in the trust as low-maintenance assets. AOWs don't typically require the ongoing attention that machine guns or suppressors might — they're not being used for shooting, they don't need maintenance, and they don't attract the regulatory attention that larger-profile items sometimes do. A small AOW holding in a larger NFA trust is often the lowest-maintenance category in the collection.

Document Your AOWs Alongside the Rest of Your Collection