I recently had the opportunity to fire the newly selected USSOCOM Suppressed Upper Receiver Group (SURG), built by SIG SAUER. It’s based on an MCX upper receiver group and is designed specifically to work with the suppressor attached. The suppressor is considered integral to the design. However, the direct thread suppressor is removable by the operator, for cleaning and maintenance. The weapon is also capable of firing without the suppressor, however there is no muzzle device. In that case, there is a gas selector, which will most often be used to deal with ammunition issues.
For the units receiving SURG, they’ll mate it to their issue M4A1 carbine lowers, giving them access to the MCX piston driven upper.
Here’s a video of me firing SURG in fully automatic mode. The upper is paired with a SIG full-auto M400 lower receiver due to availability at SIG Academy. You’ll also notice the adapter knuckle which allows the MCX upper to fit on an AR lower. Don’t take anything away from my smiling demeanor, I always look like that. And yes, it is front heavy; every firearm equipped with a suppressor shares this trait.
Although it’s not the intent, even after several magazines, the suppressor shroud could still be touched with the barehand. All the same, I don’t recommend you do this at home. Lots of variables are going to influence how hot the barrel, suppressor and shroud become and how quickly.
Instead, what this does demonstrate is that the shroud will mitigate injury and damage to equipment caused by a hot suppressor. It’s success is a combination of design and materials. There’s plenty of room for the heat to dissipate, and the Aramid cord wrap resists melting or sticking to other surfaces.
Due to SOCOM concerns, SIG is still being tight lipped about performance data, but it had to meet some very stringent selection criteria, which I went over when the upper was selected in August.
Once the SOCOM contract is fulfilled, SIG plans to offer SURG for commercial sale. However, don’t expect it to come cheap.
