Steyr's new STM 556: most definitely not a bullpup

It appears as though Steyr might have a new rifle in the works. This rifle is a pretty large departure from anything in their current catalog, it’s an AR-pattern rifle. Naturally, Steyr isn’t content to make just another AR-15 and this upcoming rifle will stand out from the pack. 

Called the STM 556, this rifle features a monolithic upper and quad-railed handguard that implements a quick-change barrel system. The rifle uses a short-stroke gas piston-operating system, and it’s adjustable with four positions for normal, over- and under-gassed settings as well as shut off. 

While we’re not positive that the rifle will be available in this configuration, photos of it at Strategie & Technik show the STM completely decked out in Magpul accessories, not just limited to furniture but also including an ambidextrous bolt release, a windowed magazine and back-up iron sights. Magpul does not recommend that their polymer MBUS sights be mounted on railed gas blocks so we wouldn’t be surprised if this isn’t the way Steyr plans on shipping their latest rifle. 


Like all Steyr rifles, the STM uses a famously-accurate cold hammer-forged barrel and famously-pretty tulip-stylized flash hider. It is chambered in 5.56x45mm NATO, and naturally can shoot .223 Remington as well. 

Details are still a little sparse, but we’re going out on a pretty sturdy limb and assuming that the receivers are constructed from billet aluminum and hard-anodized. The rifle weighs 7 pounds unloaded.

It will be interesting to see if Steyr eventually makes barrels for the STM in other calibers, too. The AR platform can host more than just 5.56, and at the very least developing a drop-in barrel chambered in .300 AAC Blackout seems like an obviously natural addition. 

STM 556 and barrels

The photos of the STM 556 show that it is a select-fire rifle. We can assume that for now the STM is being developed for military and law enforcement use, and that there could be a wait before Steyr produces a variant for the commercial market. 

We also doubt this is an end to the Steyr AUG. Just because they’re making AR rifles now doesn’t mean that they will stop making their incredibly popular bullpup, too. What would be nice is if the STM is a low-cost alternative to the AUG, but we fully expect this to be a competitor to the HK 416 and other high-end piston-driven rifles.

From just this small amount of information and a couple of photos, we’re already excited about Steyr’s new gun. The AUG will always be special to us but this thing just looks great. And hopefully we’ll get to see one hit American shores sooner rather than later. Step to it, Steyr.

Hat tip the Firearm Blog.

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