*Click to expand images
TL;DR:
The Infinity 556K is a flexible and versatile high performing rifle suppressor.
Transparency note:
The Infinity 556K was sent to us by Otter Creek Labs at no cost. As of the time of getting the suppressor and when we started writing this review, we had no business or financial relationship. However, based on more recent discussions, they'll be carrying some of our mounting parts in the near future. Regardless, we did our best to express our experiences as accurately and neutrally as possible.
We have a full disclosure page here with our relationships with all of the companies mentioned in our reviews.
Test method:
We went out to the range and shot a bunch of rounds through the Infinity 556k, Rhodie 6, CAT WB, Rhino X, and Polo K back to back multiple times. We stood in the same spots and took notes after each one for gassiness and sound. Considering I don’t have Jay’s fancy sound metering equipment, I think this is a decent way to compare them.
All of this was done outdoors with a light breeze. From the shooting position, the dirt berm was about 30 yards away. You may have different results in other environments.
Host:
The host is a tuned 12.5” mid-length rifle with the compact Plan-B brake, Aero AGB, down vent BCG, and A5H1 buffer with flatwire spring. All of the suppressors had a HUB LPA installed. We shot PMC X-TAC 55gr.
Suppressors Overview:
*Click to expand
All weights are given with no mount. The Infinity 556K has swappable end caps and was weighed with the 3 hole/medium backpressure end cap installed. It’s similar in length and weight to the other suppressors.
*The Rhodie 6 was originally listed as 15 oz, but has since been updated to 15.5 - 16.0 oz.
**The CAT WB was originally listed as up to 13.9 oz, but has since been updated to 14.6 oz.
Swappable End Caps:
The Infinity 556K has three main end caps:
9 vent holes - low backpressure
3 vent holes - medium backpressure
No vent holes - high backpressure
The standard Infinity 556K just comes with the medium backpressure end cap with the other two available separately. The Elite package comes with all three.
In most suppressors, changing out end caps only changes the sound and backpressure by a small amount. The Infinity design is different, and the end cap options meaningfully change how the suppressor functions and behaves. This makes it flexible to be better optimized for various hosts.
Backpressure:
In previous tests we’ve just given our anecdotal thoughts on how gassy the suppressor felt. This time we also used the AGB to see which gas setting was needed to lock back on the last round. We took the following steps to minimize variability:
The rifle was secured in a lead sled
All rounds were from the same lot of PMX X-TAC 55gr 5.56, and shot from the same Magpul 20 round 5.56 PMAG
After finding the minimum setting to hold open, we went up and down a setting a couple times to ensure it wasn’t a fluke
The bolt short stroking and holding back on the magazine follower (rather than the bolt catch) was not counted as a successful hold open
A lower gas setting to hold open suggests a higher amount of backpressure generated by the suppressor. Or the other way to look at it is a higher gas setting indicates lower backpressure from the suppressor.
This didn’t perfectly correlate with our experience shooting, but it was pretty close. These results are only directly comparable to shooting done on this day with this setup. Due to how many variables there are that affect cycling, this won’t match up to results from different tests.
I think I’m more gas sensitive than many people. There’s cans that I find unbearably gassy that other people blast all day and don’t mind. Environment, host, and individual factors seem to be significant here.
Rhodie 6 - Setting 9:
The Rhodie 6 had the least backpressure of the suppressors tested. This is reinforced by the perceived “gassiness” as well as the gas block setting. Towards the end of a longer string of fire or if there was zero wind we would start to get some gas, but it was quite pleasant overall. And in all fairness, even shooting unsuppressed can leave a cloud of smoke nearby in poorly ventilated areas.
Infinity 556K (9 hole end cap) - Setting 8:
The Infinity 556K with the fully vented cap held open at one setting lower than the Rhodie, suggesting slightly higher backpressure. Subjectively, it was still quite comfortable and easily fits my personal definition of “low backpressure”.
Infinity 556K (3 hole end cap) - Setting 8:
This is where our shooting experience deviates a bit from the gas settings. The 3 and 9 hole end caps both held open on setting 8, suggesting similar backpressure. However, when shooting there was noticeably more gas to the face than with the 9 hole cap. To be clear, it wasn’t a lot, and it’s still a massive improvement over a traditionally baffled can, but there is a difference. I think most people will be ok with this, and it makes sense why this is the default end cap.
CAT WB - Setting 8:
The backpressure on the WB is similar to the Infinity with the 3 hole end cap. Maybe slightly less, but it’s pretty close. Same thing, you get a little gas to the face, but not so much you’re getting gassed out and it’s affecting your shooting.
Rhino X - Setting 8:
To be honest the Rhino X is almost functionally indistinguishable from the CAT WB. They both have some backpressure and gas, but without ruining your day, and it’s a massive improvement over a high backpressure can.
Infinity 556K (closed end cap) - Setting 7:
With the closed end cap, the Infinity 556K was quite gassy and not very comfortable to me. I generally wouldn’t shoot it like this unless it was with a manual action like a bolt gun where the backpressure isn’t an issue. Or maybe if you’re the type to shoot a Polo on an untuned MK18, this would be perfect for you.
Polonium K - Setting 7:
As expected, the Polo K had the highest backpressure of these suppressors. Again, pretty gassy and not particularly comfortable. It’s easy to gas yourself out even with shorter string of fire.
Sound Performance Comparison:
As mentioned previously, the different end cap options meaningfully affect the function of the Infinity 556K. There was noticeable change in sound going from the closed to more vented end caps. It seems to be a direct trade off between backpressure and overall sound performance.
With the closed end cap (high backpressure), the Infinity 556K approached the sound performance of the Rhodie 6, but did not quite meet it.
Changing to the 3 hole (medium backpressure) end cap, the Infinity sounds slightly better than the CAT WB and Rhino X.
The 9 hole (low backpressure) end cap gets the Infinity to be louder overall than the WB and Rhino X.
The Polo K was easily the loudest of these, as you’d expect for a shorter suppressor with more basic baffle geometry.
One thing I want to emphasize is that when I say a can is “slightly” louder/quieter than another, I really mean it’s not a lot. It’s only possible to tell a difference like this because we’re shooting them back and forth on the same host multiple times. None of these cans sound bad, and I don’t think anyone would have buyers remorse or feel like they’re missing out.
Overall Opinion and Suggested Use Cases:
With an MSRP of $790, I think the Infinity 556K is a very cost effective package for a versatile, modern, high-performing 5.56 suppressor.
Being 5.5” and 15.6 oz puts it in the same length and weight range as similar options, and is very comfortable on <14.5” barrel hosts. I tend to prefer lighter cans on 16”+ barrels, but it’s totally doable there too if you’re bigger and/or stronger than me (which you likely are).
A lot of people like Otter cans, and for good reason. So if you’re thinking “man I wish I could get a Polonium with less backpressure and better overall suppression”, this is a solid contender. And while a lot of people won’t bother swapping end caps out, you do have the flexibility to do so if it fits your use case. I think it makes sense to start out with the (included) medium backpressure end cap and then only go up to 9 hole/low backpressure one if you’re running an especially backpressure sensitive host or just want a little less gas while shooting. And if you wanted to do a bolt gun with this, or are unbothered by gas in general, the closed/high backpressure cap is a good choice to maximize sound suppression.
For anyone wondering, the end cap thread pattern is not HUB, so you can’t stick a direct thread on the end and shoot the suppressor backwards, unfortunately.
This is mostly speculative on my part since we didn't do any meltdowns or durability tests, but the Infinity design seems to lend itself to excellent robustness and durability. When combined with the material choice of Haynes 282, I have no doubt this suppressor will last for a very, very long time.
The Infinity 556K is in our fitment tool. On our model, the blast baffle is a comfortable 1.69” deep which will easily accommodate standard muzzle device and adapter combinations.
Subjectively, I really like the styling of the suppressor. It’s very clean looking and has some texture near the front which allows for a good grip and likely improves heat dissipation.
This is kind of unrelated, but the model we received has a single digit serial number which I thought was pretty cool. That’s a first for us outside of form 1 cans.
Future Testing and Reviews:
Universe 36 review is coming tomorrow. We also have some more rifle suppressors which will be tested and reviewed whenever the stamps are approved.
We have plans to do more comprehensive flash testing, and made a couple changes from last time to improve the repeatability of our testing and measurements. We’ll include a couple new cans like the Infinity 556K with the different end caps to see how they do.
Whenever I get the chance to fix my Bear Creek 300BLK bolt action upper, we’ll do some more testing and comparisons of 30 cal suppressors.
Have a great weekend!
- Nathan Comstock
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