S.D.M. – Sino Defense Manufacturing is a proprietary brand designating a line of civilian-grade firearms manufactured in the People's Republic of China.
The SDM product catalog includes semi-automatic pistols such as the XM9, as well as a line of semi-automatic rifles patterned after the AR-15, M14 and AKM platforms, in addition to magazine-fed combat-style shotguns and an interesting semi-automatic bull-pup rifle.

The SDM M870 Adaptive Shotgun is the latest in a series of Chinese-made clones of the quintessentially American, and globally appreciated, Remington 870 pump-action shotgun. It offers a great price-to-quality ratio, and some features that will definitely make it interesting for shooters on a budget looking for a run-of-the-mill pump gun for hunting, property protection, or training.

The SDM M870 Adaptive Shotgun is built around a blued, machined carbon steel frame hosting a bolt that's essentially a carbon copy of that used on the Remington 870.

Just like its "American original", the M870 Adaptive Shotgun features a cross-bolt safety located behind the trigger – in contrast with other Chinese-made clones of the Remington 870 sold in the United States, such as the Ultra-87, which implemented a Mossberg-style tang safety – and a disconnector lever located on the left front side of the trigger guard.

The barrel and magazine tube of the M870 Adaptive shotgun are instead manufactured out of blued stainless steel. The tube holds up to five 12-gauge, 3"/76mm shotshells, plus a sixth one in chamber; capacity can be enhanced by installing tube extensions compatible with the Remington 870. The end cap of the tube is checkered for easy removal and integrates a front sling swivel.

The smoothbore barrel is 25 cm (20") long, integrates a cylindric choke, and can be equipped with a factory issued muzzle device machined out of blued steel, which the company refers to as the "Extreme Tactical" compensator.

The compensator lengthens the barrel to a full 22 inches, offers good muzzle climb reduction capability, and is frontally jagged to be used for breaching.

The front sight of the SDM M870 Adaptive Shotgun is a standard fixed post, while the rear sight – dubbed the "Ultimate Ghost" – is screwed on directly to the rear portion of the receiver and is fully adjustable. A standard 11mm rail is also there, providing an attachment point for optical sights, Picatinny interfaces, or others.

The furniture, however, is the most distinctive feature of the SDM M870 Adaptive Shotgun: it comes factory-issued with a MagPul SGA stock and a MagPul MOE M-LOK forend.

The MagPul SGA buttstock features a conveniently angled, checkered slip-proof pistol grip with improved ergonomics; a thick, rubberized recoil-reducing buttpad; sling loops on both sides; and a spacers system that allows the shooter to increase the length of pull from 12.½" to 14.½" in ½" increments.

The MagPul MOE M-LOK forend offers an extended length and front/rear hand stops for improved handling; also featuring M-LOK slots for accessories, it does not overlap receiver for sidesaddle compatibility and adds modularity for sporting use, home defense, or on duty.

All things considered, the SDM M870 Adaptive Shotgun is a very good choice for a run-of-the-mill, entry level firearm that a shooter on a budget may want to go for. It offers everything you need – including performance, reliability and manufacturing quality – and nothing you don't.

Being compatible with most accessories and components developed for the Remington 870 system, it can easily be modified for more enganging uses – or even converted to a bull-pup configuration – truly at a fraction of the cost of the original.