Looks like no-one has posted about this yet.  I purchased a 9.5oz. KAK Industries K-SPEC PCC buffer/flat wire spring combo, tested with a 16" and 5" barrel, and compared it to a similar weight deadblow buffer and the Gentle Recoil System (GRS).

All of the K-SPEC buffers have a spring-cushioning element build into the head of the buffers and come in standard carbine, A5, and PCC configurations.  A flat wire spring (nearly silent in the tube) and spring insertion tool are included in the package.

The buffer is phosphated and arrived completely dry from the factory. It needs a generous coat of oil for corrosion resistance and to keep the fairly tight spring from initially binding/catching on the coating.



Comparisons:

- 9.5oz. KAK K-Spec/KAK Flatwire (carbine tube)
- 9.3oz. deadblow/Wilson Combat Flatwire (carbine tube)
- 7.3oz GRS (RB5000HP hydraulic + 1 weight)/Wilson Combat Flatwire (carbine tube)
- 9.8oz GRS (RB5000HP hydraulic + 2 weights)/Wilson Combat Flatwire (A5 tube)

The hydraulic GRS cannot match the mass of the K-Spec in a carbine tube, so two comparisons were made - one that is lighter but fits in a carbine buffer tube, and one that matches the mass of the K-Spec but requires an A5 buffer tube.

16" barrel PCC tests:

- Compared to a 9.3oz. deadblow/Wilson Combat Spring, it does reduce felt recoil.  Not a big difference, but noticable. It takes the top harsh edge off the recoil.
- Compared to a 7.3oz. GRS it's pretty similar in feel. The GRS still has an edge in softness, but the impulse isn't all that different.
- Once we increase the GRS mass to match the K-Spec by adding another spacer weight (9.8oz, but requires A5 buffer tube), it's no comparison.  The GRS is noticably softer recoiling with the hydraulic buffer.

5.5" barrel 9mm PCC tests:

- Now the difference between the K-Spec and the standard deadblow weight becomes more noticable.  The K-Spec produces a significant drop in the felt recoil impulse.  Doesn't feel soft, but does feel better.
- Again, compared to the carbine tube-fit GRS (7.3oz), the recoil impulse is pretty similar with the GRS being a little softer.  
- Adding another spacer weight to the GRS to match the K-Spec's mass (and using an A5 buffer tube to fit it all) now puts the GRS in a different league.  The GRS has a much softer recoil feel.

Suppressor test:

- No real difference in gas or sound between a K-Spec and regular buffer of the same mass when using a suppressor, from what I could tell.  Expect similar performance.

Does it work?:

- Yes. It does reduce felt recoil a bit compared to a deadblow buffer and the reduction was more noticable with a shorter barrel.  The price is reasonable and it's a simple 1:1 replacement for a similar weight buffer in a carbine tube.  However, don't expect MP5 performance from it.  It's better, but not a huge difference.
- A similar-WEIGHT hydraulic buffer system does a better job of mitigating felt recoil, but requires a longer buffer tube and costs more.
- A similar-SIZE hydraulic buffer setup (carbine tube) is 2.5oz. lighter, costs more, and provides nearly the same recoil dampening feel, just slightly better.

If I was restricted to only using a carbine buffer tube, I'd get the 9.5oz. K-Spec for PCC.  It's better than a deadblow, and it's half the price of the carbine tube-length hydraulic GRS but feels almost the same to me.  If I was not limited to a carbine tube and could use an A5 or JRC tube, I'd get the GRS.

Complete article: https://blowback9.wordpress.com/2023/09/27/kak-k-spec-buffer/

Thank you for doing the review and the write-up.


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👏👏👏

Thanks for the review.  Read it on http://blowback9.com before I saw it here.

Huh I’ll probably pick one up when they’re in stock again.

Edit: I wonder if the K spec + spacer in an A5 tube would be better?

That's something I intend to test soon.

Droppoint I bought one on your recommendation for mine.  They should pay you a commission on each one they sell.   I won't be able to shoot it for a while because I am recovering from rotator cuff surgery.  Hopefully I will be able to shoot it soon. I'll make a report when I do.

if it works even better, I’ll be buying the setup in a heartbeat.

Any idea if it requires the flatwire spring they ship it with or if it can work with a standard carbine spring? Considering it for a polymer lower where flatwires aren't recommended.

It will work with a round wire carbine spring, but you'll get spring noise.

Just giving this a quick poke to see if there's any updates.

No updates yet.  Need to get my butt in gear and get out to the range, but I'm waiting for 2 more parts orders to come in so I can do all my testing at once.  Hopefully this week.

Here's the update:

Thanks for the update guess I’m ordering parts on payday.

So yeah, +1 on using that little clip to help get the flat wire spring into the buffer tube.  With the EPC I had to take the grip off and lower the upper/lower tension screw to make it work, but that made getting everything together so much simpler.

Hoping to get it to the range this weekend and test it all out.  

Holy crap, that's a HUGE improvement from the stock carbine spring and 9.6oz buffer.  I'd almost put it between a .22 and my lightweight 5.56 in recoil.  Guess I need to get off my butt and do that form 1 now.

@NorthPolar
What configuration did you end up with?  Just the K-Spec, or +additional weights?

I did the kak + one weight in an A5 tube.

I got the KAK buffer a whole ago, but with the death of my Mom, it took a back seat.  I tried it today and am very pleased.  I't's not an MP-5 but I am happy with it!!!  YMMV!!

I run the K-SPEC in my AR9 pistol & it works great & it does reduce felt recoil

I'm confused. Doesn't this mean that while the spring is compressing, most of the total buffer weight is not being used, but rather, only the bolt weight?

Seems like a better design would be a spring at the back of the buffer to push all the buffer weights forward and still have the "cushioning" effective.

It would seem that way to me, and also you just perfectly described the A5 buffer. You can make similar by finding a 9mm buffer that uses weights, or a carbine buffer plus spacer weight. Get yourself an aluminum buffer weight or brass rod. Drill a hole through it appropriate for an AR mag release spring, shorten it a hair, and chamfer it. Use it in place of the rearmost weight as a spring guide. Alternatively, what I do is use a steel-body .308 buffer and Kynshot hydraulic buffer turned backwards and placed into the other end of the action spring.

I always thought about this for all buffers.

A spring pushing all buffer weights forward would be advantageous.

How many shots have we fired where the weights were toward the rear of the buffer? Yeah it's like 1/4". But since timing is everything in the AR, especially with guns using heavier buffers like PCC's or suppressed guns, it would be extra to have as much mass forward to delay cycle vs by chance.

Back on topic: It seems like the K-spec buffer was made backwards, not using as much weight as it should when it needs it the most.