The 590 pump-action is the most produced shotgun of all time. It has been in continuous service with the US military and law enforcement since the 1980s and Mossberg has never stopped iterating. The 590RM Chisel is the most interesting variant in years — it folds, feeds from detachable magazines, and still runs the proven 590 action that has earned its reputation over decades.
The Chisel Machining Stock
Chisel Machining produced the folding stock, and it's built properly. The knuckle is machined from 7075 aluminum — the same alloy used in AR lower receivers — with a push-button locking mechanism that holds locked in both the extended and folded positions. The stock attaches via a buffer tube-style mount that accepts M4-compatible stocks in eight length-of-pull positions, from 12.5 to 16.5 inches. When folded, the stock clears the receiver cleanly without snagging on the action or the magazine port.
Magazine-Fed Operation
The RM designation means detachable magazine. Mossberg's double-stack magazines for the 590 platform were the first production double-stack pump-action shotgun magazines when they were introduced — not a common thing in the industry. The magazine engages the receiver with integral stabilizing ribs for a positive lockup. For tactical applications where speed reloads matter more than hunting-style tube management, the RM configuration makes the 590 a genuinely different tool.
NFA Status
The 590RM Chisel is a Class 3 firearm — the folding stock and short configuration place it in NFA regulated territory. At $0 tax stamp, that's a different calculation than it was two years ago. Budget the $200 tax stamp cost on top of the $1,435 MSRP if you're buying this as-configured from a licensed dealer.
Specs
Gauge: 12 | Operation: Pump-action | Feed: Detachable double-stack magazine | Stock: Chisel 7075 aluminum folding | LOP adjustment: 12.5–16.5 inches | NFA: Yes | MSRP: $1,435
Bottom Line: A folding, magazine-fed 590 is the most tactically configurable pump shotgun Mossberg has built. If you've been waiting to pick up an NFA item while the stamp is free, this is a strong candidate.
