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Posted: 5/27/2026 10:25:44 AM EDT
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Currently using the blowback 9 recommended A5 tube with 10oz 9mm 4" buffer + kynshot 2.5oz spacer with a standard carbine spring OR flatwire carbine spring - and when shooting it feels like an absolute hammer. So much recoil and weight moving in the buffer tube its just not smooth at all. I was wondering if anyone has used a sprinco white or blue from their AR15 setups in a 9mm pcc instead of the standard carbine? Or some other combo that makes recoil not as jarring? |
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Originally Posted By the-answer-is-42: Currently using the blowback 9 recommended A5 tube with 10oz 9mm 4" buffer + kynshot 2.5oz spacer with a standard carbine spring OR flatwire carbine spring - and when shooting it feels like an absolute hammer. So much recoil and weight moving in the buffer tube its just not smooth at all. I was wondering if anyone has used a sprinco white or blue from their AR15 setups in a 9mm pcc instead of the standard carbine? Or some other combo that makes recoil not as jarring? His preferred setup for use with an FRT / SS is the A5 tube like you mentioned but with the Kynshot hydraulic 5000HP and a flat spring. Which flat spring are you using? Are you using an FRT / SS or real full auto? If not, he prefers the JRC tube. I run full auto and use the CMMG RDB setup as I prefer low reciprocating mass which you can't get away from with straight blowback. |
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Recoil is subjective, so I suppose your experience will depend on your perspective - E.g., what you are comparing to. Compared to a gas 556, I agree Blowback 9s GRS has more recoil. I run his GRS as spec'd with Tubbs flat wire, 2x spacer weights and the kynshot hydraulic he spec'd. I expect the additional weight in my system allows more pressure to dissipate through the muzzle before the buffer starts buffering. Since I've never run the single spacer weight version, I can't say how much difference this attributes to my experience. My point of comparison is a very similar blowback 9mm AR buffered by a 10.5oz sliding weight buffer. If I was gonna try to drive a nail, the non GRS would surely be faster than my GRS'd AR9. So, I'm pleased as punch with the GRS. Blowback9 has videos and white papers comparing the systems he has spec'd - probably the best resource for you to determine whether the 2x spacer weight might provide you adequate relief. My experience with non AR blowback 9s does confirm that additional weight takes the edge off of recoil. I also experimented with the Maxim Defense Roller Delayed Buffer. Ultimately, the RDB system had gentler recoil than my GRS. But I store it in a parts bin 'cause rates of fire. Recoil did compare reasonably with 556. My suggestion for you is to seriously weigh the cost/benefit of moving to a delayed (roller, radial, ...) blowback upper. The delayed systems are gaining popularity quickly because of their improved recoil characteristics. I see Amphibian has also replied - he's your resource if you make the move to delayed blowback. |
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I’m re-entering AR in 9mm fun. Why is the current recommendation to such heavy buffers? Is it due to suppressors/cans? My Colt had some all steel 2 piece buffer & was (per internet) around 5.6oz. The bigger issues were feeding/jamming. It went to Colt twice & never got fixed, so I sold it. So now I’m wondering if the issue was the buffer was too light? I was surprised to find I still have one of the Cot buffers & was planning on using it, but now think it may not be wise. Yes, I’ve read blowback9’s site. Guess I need to find the videos. |
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Originally Posted By amphibian: I assume you already reviewed Blowback9's website? https://blowback9.wordpress.com/2023/05/28/9mm-ar-gentle-recoil-buffer-system-final/ His preferred setup for use with an FRT / SS is the A5 tube like you mentioned but with the Kynshot hydraulic 5000HP and a flat spring. Which flat spring are you using? Are you using an FRT / SS or real full auto? If not, he prefers the JRC tube. I run full auto and use the CMMG RDB setup as I prefer low reciprocating mass which you can't get away from with straight blowback. Yes I have this setup because of his website. I am not using an FRT/SS and its semi only. I was using the Strike Industries flatwire carbine spring but it looks like he now does not recommend it for use. It's too strong? Maybe thats why. I assume I can use a standard carbine spring with his budget GRS buffer recommendations it just wont have the 'sproing' reduction in noise of the flatwire spring. |
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There is a formula to use to figure an approximate weight, based on bullet weight and velocity. So, it helps, though it’s not necessary, to have a Chronograph. BW/437.5 x V = MNW x V Translation. Bullet Weight in grains divided by 437.5 converts Bullet Weight to ounces. This is multiplied by the Bullet Velocity. Since you need to find out the moving mass weight of the bolt and buffer, divide that figure by the design speed of the action. I’ve seen 2 speeds used………17.5fps and 18fps. I use 17.5. There’s really not a lot of difference between the two. For example, I’m using hot loaded 9mm 124gr bullets in my Carbine, which chronos around 1425fps . So, the formula would be 124/437.5 x 1425fps. That number divided by 17.5, which should give a number around 23oz. If I use the 18fps number, I get a moving weight of 22.4oz. Since I’m using a moving weight of about 22oz, it’s in the ball park. I can fine tune from there. Remember, with shorter barrels, and/or lighter loads, your results will be different. This is using a standard AR spring. I’ve used the same formula for finding the weight of my bolt/buffer combo in my 10mm, though I’ve had no use a .308 rifle strength spring. |
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My current set up PSA 635 clone (10.5") and PSA h&r bcg KAK 10oz tungsten buffer Standard carbine recoil spring Rare breed style FRT Runs super well as seen here:  PSA AR9 FRT-15L3 10oz buffer (NOT FULL AUTO) COLT M635 SMG style 9mm Possibly considering going to a sprinco white hot to perhaps slow the rate of fire just a hair. |
Most of you have already seen this video that David Tubbs made a dozen or more years ago. For those of you that haven't seen this video, I found that it really helped me understand the differences in buffer springs. Everything You Should Know About AR Buffer Springs |
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| I just bought a Daniel Defense PCC 9 pistol and put a Huxwrx Flow 9k ti on it. I saw a video where the guy recommended a Springco orange for a suppressed blowback 9 so I gave it a try. It slowed the bolt down where it ejects about 2 0’clock and the recoil impulse is very similar to my JP Enterprises roller gun. For $20 spring testing and experimentation is cheap |
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