Suppressors HUXWRX FLOW 556K vs FLOW 6K

Are you planning on using it for 6mm, like 6mm arc, or just 5.56?

If its the latter, its been proven that a flow 762 outperforms the 556k on 5.56 suppression. It likely would for 6mm calibers too. I also would look at the flow 556 (not K) model.

K cans overall seem to be less-than-ideal in most scenarios if you're looking for overall sound suppression.

I don’t have the 556k to compare but I do have the 6k. It’s pretty much the only van I’ve regretted buying. It’s extremely loud

JohnDeereGuy1996 said:

I don’t have the 556k to compare but I do have the 6k. It’s pretty much the only van I’ve regretted buying. It’s extremely loud

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Im in the same boat. If I could get rid of my flow 556k, I would. Even if it meant taking a hit on it at used pricing.

Shooting it on a mk18 host...its just not impressive like the other cans Ive shot. Im sure a short barrel provides it own challenges too..but its the ideal barrel length for a suppressed 5.56 AR pistol.

AleksanderSuave said:

Im in the same boat. If I could get rid of my flow 556k, I would. Even if it meant taking a hit on it at used pricing.

Shooting it on a mk18 host...its just not impressive like the other cans Ive shot. Im sure a short barrel provides it own challenges too..but its the ideal barrel length for a suppressed 5.56 AR pistol.

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My Kac mcq seems to suppress better than the 6k. It’s hard to tell it’s doing anything honestly.

JohnDeereGuy1996 said:

My Kac mcq seems to suppress better than the 6k. It’s hard to tell it’s doing anything honestly.

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Ive shot mine without earmuffs and its "tolerable" but definitely not something I'd want to sit through a full mag on.

My CGS can, on the other hand, could shoot all day without muffs, without subs, and its like a quiet 22.

AleksanderSuave said:

Im in the same boat. If I could get rid of my flow 556k, I would. Even if it meant taking a hit on it at used pricing.

Shooting it on a mk18 host...its just not impressive like the other cans Ive shot. Im sure a short barrel provides it own challenges too..but its the ideal barrel length for a suppressed 5.56 AR pistol.

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AleksanderSuave said:

Ive shot mine without earmuffs and its "tolerable" but definitely not something I'd want to sit through a full mag on.

My CGS can, on the other hand, could shoot all day without muffs, without subs, and its like a quiet 22.

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Been looking at the flow 556k and I’m torn between that and the Velos K for my Mk18. What other cans have you find that worked better on the 10.3” set up.

MaxVY said:

Been looking at the flow 556k and I’m torn between that and the Velos K for my Mk18. What other cans have you find that worked better on the 10.3” set up.

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I would look into the B&T Print XH series cans.

MaxVY said:

Been looking at the flow 556k and I’m torn between that and the Velos K for my Mk18. What other cans have you find that worked better on the 10.3” set up.

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CAT has some significantly better options

I got the 556K because the 6K wasn’t available anywhere that I wanted to do business with. If the 6K had been available I would have gotten it for versatility. A .019” bigger hole makes a diddly fuck of a difference when shooting 5.56 and it gives you the ability to slap it on a 6ARC too.

I have a PTR VENT 3 (.556) and 1 (.30 cal). Both are fantastic, sounds like a fairly quiet nail gun. They are a bit on the big side, however are not Noticably heavy for me. I have a CAT WB inconel ordered and will compare when I get it. $200 free tax stamp at Silencer Shop on the CAT WB talked me into it.

The PTR cans are something special. Its amazing how they came out of nowhere and made cans the perform better than anything on the market.


I think the Hux 6K is the golidlocks can. I would buy it before the 556.

I would love to have one for my 6 arc gas gun, but it has a KGM R30K. Cant really stomach the $1200 to upgrade it.

Other than their weird marketing. Cat cans are pretty freaking awesome. My Johnny law compares very favorably to my 338 ultra sound wise on a bolt gun. If I’m looking at new suppresors I’m starting with theirs.

While I own suppressors and use them on various rifles and pistols, they almost always make the host system worse somehow (accuracy, reliability, gassier, change of balance, ect)

More directly to your question, on something like a MK18 even when you are behind the gun I am not sure that there is any suppressor that would make it hearing safe. Now that we are getting more rounds on them, I am kind of getting down on some of the newer 3D printed designs (difficult to clean, louder than traditional baffles sometimes, burps fire or sparks sometimes, more delicate (we have seen three cans burst with use). Rock solid reliability recommendations include Surefire, KAC, and the CGS. Best budget is probably the Polonium (ottercreek).

I've got both the Flow 556k and the Flow 6k in my rotation—picked up the 6k specifically for my 6ARC build after running the 556k on a couple 5.56 SBRs (including a 10.3" MK18 clone). Direct head-to-head isn't out from Pew Science yet on the 6k, but from what I've seen in their 556k review and some side-by-side YouTube metering (like the quick comparison shorts floating around), the differences boil down to bore size and versatility without much sacrifice in performance.
On straight 5.56, the 556k edges out slightly in at-ear suppression (Pew clocks it around 38 on the MK18, low backpressure keeps gas out of your face), but the 6k's .243 bore doesn't hurt it much—maybe a dB or two louder at the muzzle, but the flow-through design still shines for reduced blowback and heat management on full-auto dumps or rapid fire. Tone-wise, the 6k feels a hair less "boomy" on 5.56 than the 556k, which some folks complain about, but YMMV based on host and ammo. For 6mm calibers like ARC or Creedmoor, the 6k is the clear winner; the larger exit aperture optimizes flow without clipping, and I've noticed better grouping consistency over longer sessions compared to running a .30 cal can like my old Surefire.
Weight and length are near-identical (both ~5.5" and under 13oz), so no real handling penalty swapping between them. Mounting is the same QD system, rock-solid. If your primary is 5.56-only, stick with the 556k for the tighter bore match—it's a beast for K-cans in backpressure reduction. But if you're eyeing 6mm or multi-cal use, the 6k's modularity justifies the extra $100-ish. Regrets mentioned here align with short-barrel quirks; on anything under 11.5", no K-can is "quiet" without subs, but these outperform my old RC2 in gas control.
OP, what's your host setup and primary caliber? If it's a gasser like 6ARC, I'd lean 6k all day. Anyone else meter them back-to-back on the same rifle?

Sorrry, double post