Good afternoon everyone and welcome back to TFB’s Silencer Saturday brought to you by Yankee Hill Machine, manufacturers of the new YHM R45 Multi-Host Suppressor. Last week we got a look at that new YHM R45 and we’ll be back with a full report… on the report. This week we’ve got the brand new YHM Fat Cat 5.56 rifle suppressor – can short and fat perform just as well as thin and long? Let’s find out if that’s what she said.

More YHM @ TFB:

• [SHOT 2023] YHM Fat Cat 5.56 Silencer
• SILENCER SATURDAY #284: YHM Phantom 22 Rimfire Maintenance
• SILENCER SATURDAY #257: Limit TOXIC EXPOSURE – The New YHM Turbo T3 Suppressor
• SILENCER SATURDAY #112: YHM Resonator K – Quiet, Short, Light, Affordable

Editor’s Note: YHM has been a sponsor of TFB’s Silencer Saturday for several years. Without their support, you wouldn’t have my purrsonality intruding into your lives every Saturday. But YHM knows that my goal is to be as unbiased as possible and I will tell you if a product doesn’t perform. The intent is to provide you with the information you need to spend your money on guns a silencers that will make you happy for all of your nine lives.

In Memoriam

This YHM Fat Cat review is dedicated to Cookie, our barn cat that died last week at the age of 16. She got a TFB mention in our 2017 April Fools post. See you on the other side Cookster.

SILENCER SATURDAY #288: The YHM Fat Cat – Not Kitten Around Meow!

As I like to remind everyone , I am not an engineer, but I do like to pretend that I am from time to time. I throw around terms like hoop stress, fluid dynamics, and tubular flow like dollar bills at a port-side strip club. My intention was to dive into Stokes Flow and the slender-body theory as an analysis of the performance gasses traveling through different tube sizes. But I realized very quickly that the chances of me making a fool of myself were rapidly approaching 100%.

Talking with talented industry engineers over the years, my takeaways have been that the internal volume created by short suppressors with large diameters is better suited to slow-moving subsonic rounds where the expanding gasses have somewhat lower velocities and can reach the outer edges of the baffle geometries. In contrast, the fast-moving gases of supersonic rounds benefit from a longer tube with more baffles.

Above: (top to bottom) YHM R45, YHM Turbo K-RB with full size mount, YHM Turbo K with direct thread, YHM Fat Cat wit sRx mount.

Larger diameters in longer suppressors will increase weight with diminishing returns because of the additional materials for more volume and additional strength to deal with the added hoop stress. Hoop stresses, using the thin-walled vessel assumption, are expressed in inch pounds-force per square inch as internal pressure (Pr) over the radius (t) of the cylinder.  In short, hoop stresses are twice that of longitudinal stresses inside of closed pressure vessels.

And I have now crossed over into the territory of “but I did stay at a Holiday Inn Express last night”.

There are always exceptions to the rules. Especially with the increased use of additive manufacturing, internal baffle designs can take advantage of the the additional diameter in short/fat cans for fast moving bullets and gasses.

I love the look of the Fat Cat with a tapered flare that expands into the main tube that is just shy of two inches in diameter, My initial thought was ‘why not just make the whole suppressor the tube?’ and take advantage of the additional volume. But, after researching hoop stress, the narrower diameter is probably required to deal with the higher pressures found in the blast chamber. The main body is comprised of a few baffles that are spread farther apart to allow those supersonic gases to utilize the volume and geometry out to the side walls.

Thus ends the mangled physics lesson for today’s Silencer Saturday. Let’s take a look at the numbers.

Meet The Fat Cat -The newest member of the YHM suppressor family! This 5.56 NATO suppressor sports new baffle geometry resulting in reduced blowback. Built with the same care, quality, and attention to detail that has defined the YHM® brand for generations, the Fat Cat® was created to provide a compact suppressor with great sound. The Fat Cat® is made from 17-4 stainless steel along with a heat-treated 718 Inconel blast baffle. The combination of these materials allows the suppressor to be full auto-rated and designed for rigorous use. The overall length measures just 4.5″ with the sRx adapter installed. That’s a full inch shorter than our Turbo K model with its included adapter. The Fat Cat’s larger 1.94” diameter creates more internal volume resulting in a lower, more pleasant tone. With an average sound pressure level of 141dB at the muzzle, the Fat Cat® is quite the performer for its size. Also available is the optional cat end cap, YHM-2210, with the Cat’s Ass design on the cap. The Fat Cat® includes the Mini sRx Mount and 2 suppressor tools.

• SKU: YHM-2200; YHM-2210 (Cat Butt)
• Manufacturer’s Page: https://yhm.net/556-suppressors/fat-cat-suppressor/
• Owner’s Manual: Click here
• MSRP: $659
• Weight: 10.6 oz – W/adapter – 12.5 oz
• Length: 4.25″ – W/adapter – 4.50″
• Diameter: 1.94″
• Attachment: sRx Adapter 1.375 x 24 – HUB
• Construction: 17-4 Ph SS / Inconel
• Finish: High temperature black Cerakote
• Mount: sRx Adapter with 1-3/8″-24 HUB Interface
• Minimum Barrel Lengths: 10″ (5.56mm)

My platform for today’s testing is the Knight’s Armament KAC SR-15 11.5″ upper receiver with a carbine length gas system. I’m sure I will be destroyed by the MK18 fan club, my personal barrel length limit for the  5.56mm NATO round is anything over 11″. If you have the benefit of high-performing ammo like M855A1, a 10.3″ barrel might be sufficient. As a reminder, 5.56mm bullets are light and designed to perform best at higher velocities. And barrel length is all about muzzle velocity.

Point being, I have a MK18 barrel to test the YHM Fat Cat’s minimum barrel length, but my favorite setup is the 11.5 KAC.

Supersonic rifle suppressors are always harder to evaluate than subsonic rifle suppressors. The fact is, rifles, especially those with short barrels, will be loud requiring the use of hearing protection. We can pore  over (thanks for the grammar lesson, James) meter numbers and draw comparisons to other industry options, but in the end it is the other attributes that are much more important than raw noise suppression.

Length, weight, mounting systems, and a respectable noise suppression level for a short barreled rifle put the YHM Fat Cat above more expensive choices for a K-size suppressor. Basically, it does its job well with all the important options at the right price. Quiet? No. But it’s basically impossible to make a short can on a short barrel sound “quiet”.

To top it all off, the Fat Cat looks great.

Have a great week. Be safe, have fun, and we’ll see you back here next weekend for another Silencer Saturday.

---

SILENCER SHOP – HANSOHN BROTHERS – DEADEYE GUNS

MAC TACTICAL

ALL YHM PRODUCTS AT BROWNELLS

DEALERS: If you want your link to buy YHM suppressors included in future Silencer Saturday posts, email: silencers@thefirearmblog.com