SILENCER SATURDAY #325: Small Simplicity – SIG Sauer SLX556C

by Pete
SILENCER SATURDAY #325: Small Simplicity – SIG Sauer SLX556C

Good afternoon everyone and welcome back to TFB’s Silencer Saturday brought to you by Yankee Hill Machine, manufacturers of the brand new YHM 338 Bad Larry Suppressor. I would like to thank Erik for running point on last weeks edition with a look at the very obtainable suppressors from The Nordic region. This week we get back on the range with a simple and compact direct thread rifle suppressor – the SIG Sauer SLX556C. When it comes to longer barrels and supersonic rifle rounds, compact silencers are a blessing. Let’s take a look at this small but mighty can from SIG.

More SIG Sauer SLX and SLH Suppressors @ TFB:

Firearms/Gear used in today’s review:

SILENCER SATURDAY #325: Small Simplicity - SIG Sauer SLX556C

IMPORTANT: I believe regulations on firearms like short barrel rifles (SBRs) and silencers should be eliminated, and hopefully one day that will happen. However, current laws restrict barrel lengths and the making, ownership, and transfer of these firearms. Before modifying any firearm, please take the time to understand your local, state, and federal firearms laws. Adding a stock to a pistol constitutes making an SBR and requires an approved ATF application and tax stamp (for non-licensees).

SILENCER SATURDAY #325: Small Simplicity – SIG Sauer SLX556C

SILENCER SATURDAY #325: Small Simplicity - SIG Sauer SLX556C

We are back in the saddle with some reviews after a few weeks of editorials – new product releases have been in relatively short supply for the past few months. I have a short list of new models queued up, but if you have any suggestions, please drop me an email or a post a comment below. Again, I’d like to thank Erik for handling the series last week; it’s really nice to be back in the U.S. after literally having to circle the globe to get home.

Fresh off the truck from my favorite FedEx delivery driver less than 24 hours ago is the SIG Sauer SLX556C compact direct thread rifle suppressor. SIG was nice enough to let me borrow this pocket-sized 5.56mm silencer for an upcoming review of the new MCX-Regulator. I have to say, they know me so well that I didn’t even have to ask for a compact 5.56 suppressor for the MCX-R review. I do have a deep appreciation for the MCX platform, and my love of suppressors makes for a perfect pairing.

For those of you who are turning up your nose at this sporterized version of a fighting carbine, I would ask you to withhold your final judgements until I can get more trigger time on the MCX-Regulator. It is a unique adaptation of a capable platform and my initial impressions are all positive. I will also admit that I have not had the chance to finish James Reeves’ video on this rifle, mostly because I don’t like watching other reviews before completing my own, but also my eyes start to glaze over when his 5” inseam shorts take the stage.

SILENCER SATURDAY #325: Small Simplicity - SIG Sauer SLX556C

At the risk of alienating both SIG Sauer and FN America, the SLX556C make an appearance on the FN SCAR 15P in today’s review. I recently picked up the SCAR-SC stock from Arms Unlimited and have been waiting for an excuse to debut it here on Silencer Saturday. Admittedly, my love for the MCX is solidly entrenched in 300BLK. Also, FN does not currently offer a 5.56 suppressor. So I’m hoping that both manufacturers will let my transgressions slide in the name of both science and enjoyment.

One of the reasons that the FN SCAR 15P, now an FN SCAR-SC short barrel rifle, is important for today’s review is because of the 7.5” barrel length. The reason barrel length restrictions exist for some models of suppressors is because of the dramatic rise in muzzle pressure as barrel lengths decrease. For instance, the muzzle pressure of a 5.56 round in a 7.5” barrel is nearly twice the muzzle pressure of a 5.56 round in a 12” barrel.

That pressure, heat, and unburnt powder can exceed the max safety limits in some suppressors. In others that do not have defined barrel length restrictions, that heat and pressure will increase baffle erosion rates. Needless to say, it is important to read all of the user documentation and understand the limits of your suppressors. When in doubt, contact customer service before risking damage to your suppressor or serious injuries to yourself or bystanders.

While I am generally opposed to 5.56 chambered guns with barrel lengths less than 11.5” for reasons I articulated in the FN SCAR 15-P review, I understand that there are users who have a need/requirement for more compact platforms like the MK18 and the SCAR-SC. And because of the amount of unburnt powder exiting the muzzle, these guns will always be loud. Really loud. Even with the best suppressors on the market. Somewhat counterintuitively, my suggestion is to run a compact suppressor on ultra-short barrels because, if the muzzle blast is always going to be loud, you might as well preserve the short overall length of the whole platform. If you are going to add inches anywhere, I would suggest that the barrel is the best place for that to happen.

Manufactured with Inconel and using additive manufacturing processes, the SIG Sauer SLX suppressors are practically bomb-proof. With no listed barrel restrictions, running the SLX556C on the FN SCAR 15P should not be a safety issue. And with the multi-flow gas pathways, the SLX556C will let pressure vent forward and out of the muzzle instead of back into the action of the weapon where it could cause malfunctions and possibly damage to the receiver. As I mentioned in the SCAR 15P review, it’s always best to contact FN before adding a suppressor on to the end of a SCAR.

Let’s take a look at the numbers.

SIG Sauer SLX556C Suppressor
SILENCER SATURDAY #325: Small Simplicity - SIG Sauer SLX556C

SILENCER SATURDAY #325: Small Simplicity - SIG Sauer SLX556C

Moving from short barrels to longer barrels in a 5.56 platform, I still suggest that a short suppressor might be a decent choice for most shooters. Because longer barrels have the ability to burn more powder behind the bullet instead of outside of the muzzle, a suppressor has to do less work to tame the report. But long barrels with long suppressors make for unwieldy platforms. And because no supersonic rifle rounds will ever be “hearing safe”, my suggestion is to once again prioritize overall length over trying to squeeze out a few more decibels with a longer can.

The SLX556C performs admirably on both the FN SCAR 15P and the SIG MCX-Regulator. The “Baby SCAR” will never get close to “quiet”, but it will contain the concussive blast enough for you to maintain your senses. On the other hand, on the 16” MCX-R, the SLX556C does a nice job of reducing the report considering it’s small size.

SILENCER SATURDAY #325: Small Simplicity - SIG Sauer SLX556C

My two detractors for this suppressor are price and weight. With a street price somewhere between $899 and $999, the direct thread SLX suppressors are on the upper side of the industry pricing scale. And at 12.6 ounces, it’s not as light as I would like it to be (10 ounces would have been perfect).

On the other hand, the SLX silencers are expertly engineered, about as robust as you can get without adding six or more additional ounces, and perform very well on longer barrels. I won’t attempt to comment on the ultra-short barrel performance since any suppressor trying to tame the muzzle blast from a 7.5” barrel will be labeled as an “underperformer”.

As the family SIG suppressors go, this is probably the best value to performance ratio model available, providing a no-nonsense tapered direct-thread attachment, solid performance for it’s size, priced lower than the QD models, while still maintaining the near indestructible properties of a 3D printed Inconel pressure vessel. If size is your biggest problem, this is a great solution.

That’s what she said.

SILENCER SATURDAY #325: Small Simplicity - SIG Sauer SLX556C

Thanks for reading. Be safe, have fun, and we’ll see you back here next week for another Silencer Saturday.




DEALERS: If you want your link to buy YHM suppressors included in future Silencer Saturday posts, email:

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6 of 15 comments
  • Clairvoyant Clairvoyant on Apr 21, 2024

    Living in a bizarre fantasy world, or, go join a real army and start fighting somewhere. Oh no, not that, better to live in your fantasy. Pathetic

    • See 3 previous
    • Plumber576 Plumber576 on Apr 21, 2024

      @Clairvoyant After viewing comment history, I think this angry person is lost.

      Good luck finding your way home, wherever that may be!

  • Jason Levy Jason Levy on Apr 26, 2024

    There is a lot of discussion on unburned powder vs barrel length. This is a common misconception. All the powder that's going to burn occurs in the first 1-3 inches of the barrel. You can see this clearly in the ar-15 pressure vs barrel length curves where the powder is burned at or just after the peak. The flash you see is superheated flammable gasses mixing with air and lighting off.