CMMG RDB 9mm SBR FRT ROF Testing

[strobro32]

https://flic.kr/p/2s9vB4u

 

[StenAtopia]

Nice rof

 

[strobro32]

Thanks to C3junkie's work.

 

[Offmarksman]

What work was done to the upper?

 

[strobro32]

None.

Just keep in mind that CMMG RDB FE 9mm and 45 acp has lots of reported problems with CS, shipping, firing pin, firing pin spring, cam. barrel head space and bolt breakage reports, along with wear "they don't anodize the aluminum before Cerakote application. Those plus the Gucci prices. F.CMMG is a love/hate relationship.

The lower has a A5 buffer tube, Tubbs 5,56 flat wire spring, Kynshot RB5007 buffer, AS Designs V2 FRT. I wanted to get another RB5007 but they are OOS everywhere.

Amphibian says he's been testing a new Kynshot buffer because they are going to sell a sightly modified new one. I'm looking forward to it.

 

[amphibian]

None.

The lower has a A5 buffer tube, Tubbs 5,56 flat wire spring, Kynshot RB5007 buffer, AS Designs V2 FRT. I wanted to get another RB5007 but they are OOS everywhere. C3junkie says he's been testing a new Kynshot buffer because they are going to sell a sightly modified new one. I'm looking forward to it.

Yes, I tested the new Kynshot prototype last weekend and myself and a recently retired LE firearms instructor also helped me doing some comparisons. I was also testing a magnetic buffer I made which he said was better than the RB5007 and says is still slightly better in full auto than the new hydraulic Kynshot. However, they are all close. We rated it like this.

For full auto.
1. magnetic prototype
2. new kynshot prototype
3. RB5007

However for slow fire or semi.
1. new kynshot prototype
2. magnetic prototype
3. RB5007

My friend is also a lefty and more sensitive to gas to the face. When running suppressed and less gas this is the rating.
1. New Kynshot prototype
2. RB5007
3. magnetic prototype

Now I have a ton of other buffers so you can assume they are obviously not as good as these and again, very close and you may not be able to tell without shooting them back to back.

This was running my 9mm 8" CMMG RDB setup with a lightened carrier and suppressed with a can I built. Same length as the CT9KS but the baffles are conical and push out for disassembly. Coaxial so old school low backpressure.
I am seeing about a 30RPM decrease in the cyclic rate to the original RB5007.

I plan to go out this weekend to do some more testing with it in 556. I see no reason why it wouldn't perform even better than the 5007 for the same reasons why I think it performed so well in 9mm.
I have it all documented on my site here: https://c3junkie.com/?page_id=2757
I stated, "Now if you look at my live fire video which is in the link above and I have pasted below for convenience and watch the first 5 seconds you can see the buffer body move forward on that initial recoil impulse."
In several forum posts I stated that I would like it to be lighter dampening with a weaker spring so that the body would move forward even more than it does now. This would spread the impulse over a longer period of time and I think that is what is happening now. I did some high speed video but the lighting was that good and you can't really see the difference so I need to do that over.

I will be offering these new hydraulics for sale on my site once they are made available to me.

 

[strobro32]

Is the magnetic buffer going to work with a SS/FRT?

 

[amphibian]

Is the magnetic buffer going to work with a SS/FRT?

There is a guy on Reddit that posted that the magnetic messes with the SS as it magnetizes the carrier which causes issues. However, that doesn't seem to be an issue with a Rarebreed, Partisan Disruptor or AZ Regulator.

 

[strobro32]

I reddit too.

With all the SS lever material, stainless steel, 4140, S7 and D2, I wonder which lever material he tested?

 

[SecondAmend]

Yes, I tested the new Kynshot prototype last weekend and myself and a recently retired LE firearms instructor also helped me doing some comparisons. I was also testing a magnetic buffer I made which he said was better than the RB5007 and says is still slightly better in full auto than the new hydraulic Kynshot. However, they are all close. We rated it like this.

For full auto.
1. magnetic prototype
2. new kynshot prototype
3. RB5007

However for slow fire or semi.
1. new kynshot prototype
2. magnetic prototype
3. RB5007

My friend is also a lefty and more sensitive to gas to the face. When running suppressed and less gas this is the rating.
1. magnetic prototype
2. RB5007
3. magnetic prototype

Now I have a ton of other buffers so you can assume they are obviously not as good as these and again, very close and you may not be able to tell without shooting them back to back.

This was running my 9mm 8" CMMG RDB setup with a lightened carrier and suppressed with a can I built. Same length as the CT9KS but the baffles are conical and push out for disassembly. Coaxial so old school low backpressure.
I am seeing about a 30RPM decrease in the cyclic rate to the original RB5007.

I plan to go out this weekend to do some more testing with it in 556. I see no reason why it wouldn't perform even better than the 5007 for the same reasons why I think it performed so well in 9mm.
I have it all documented on my site here: https://c3junkie.com/?page_id=2757
I stated, "Now if you look at my live fire video which is in the link above and I have pasted below for convenience and watch the first 5 seconds you can see the buffer body move forward on that initial recoil impulse."
In several forum posts I stated that I would like it to be lighter dampening with a weaker spring so that the body would move forward even more than it does now. This would spread the impulse over a longer period of time and I think that is what is happening now. I did some high speed video but the lighting was that good and you can't really see the difference so I need to do that over.

I will be offering these new hydraulics for sale on my site once they are made available to me.

Thanks for posting. The buffer comparison shooting I did a few years ago had the B & T AR9 buffer coming out with somewhat lower ROF for 9mm and .45ACP than any of the several KynSHOT models that were available at the time. As I prefer to "buy American", it's good to see KynSHOT working on new stuff.
MHO, YMMV, etc.