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Posted: 7/1/2025 8:43:55 PM EDT
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Anyone else ever try a Kynshot RB5007 9mm buffer in a 5.56 AR? I used one today in a 16" carbine and it worked perfectly. I, of course have an A5 buffer tube on the rifle so that it could accommodate the 3/4" longer buffer. I had installed a Tubb flat-wire buffer spring previously. I thought it was extremely soft shooing using M855, 62gr. g.i. ball ammo. Ejection was perfect at 4 o'clock. Next time I get to the range I'm going to change to a Sprinco red buffer spring just to see what it does. Then I'm going to change to an RB5015HD buffer with the Tubb spring, and if that combo works, add the red spring. Yeah, I've got a lot of time to tinker.  If you've tried it already, what were your results? |
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I think I came up with that combo and have been posting about it since around 2017. https://c3junkie.com/?page_id=977 |
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Quoted: I think I came up with that combo and have been posting about it since around 2017. https://c3junkie.com/?page_id=977 How about the 5015? |
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Quoted: I think I came up with that combo and have been posting about it since around 2017. https://c3junkie.com/?page_id=977 |
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Quoted: How about the 5015? Quoted: Quoted: I think I came up with that combo and have been posting about it since around 2017. https://c3junkie.com/?page_id=977 How about the 5015? |
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I have posted this many times and probably just need to update my website for this but here it is again. 1. I try to do all my tuning in the upper. So for a gas operated setup, it is 'gassed' the way I want it. More on that later. 2. I like the CMMG RDB setup but I also do certain things for tuning it mechanically as discussed on my setup here: https://c3junkie.com/?page_id=1733 That said, a common scenario for a lot of people is to use the same lower for 556, 300BLK and a 9mm CMMG RDB setup. You can run all of those with the same lower w/ an A5, RB5007 and an appropriate flat spring and just swap uppers with zero changes in the lower which is great for convenience and less chance of making mistake by forgetting to change something in the lower or having to bring more stuff to the range. Many people may just opt for getting dedicated lowers but in my case, I run full auto and have transferrable lowers and I don't have multiple transferrable full auto lowers. Some people may also only have 1 lower equipped with a SS / FRT or their one lower is an SBR so using one lower is convenient. The Tubb 556 works on all those calibers. The Tubb LW spring is great for 300BLK and 9mm but typically too weak for 556. The Neverwear Warthog spring is between those two and I good compromise. All that said, I typically recommend the above since again there is less chance of a misconfiguration or again forgetting something. If you want to go down the rabbit hole, see what I have done here with extended stroke: https://c3junkie.com/?page_id=1403   With the BCG not bottoming out, this is the smoothest 556 M16 I have ever fired. Thread where I let someone try it: https://uzitalk.com/forums/index.php?threads/amphibian%E2%80%99s-m16-set-up.101027/  The Ultimate M16 by Amphibian! (The ROF is mint). There is no gas to the face and no special charging handles.....This is because the dwell time is so long. Combining an optimal size gas port with a large volume gas tube takes more time to fill the gas tube so the gas goes out the front instead of back into your action / face. I am doing the same thing now in 9mm:  All that said, for these extended stroke configurations, I am now using the even longer JRC tube, RB5007 and now the appropriate amount of spacers. Pictured above is a Delrin spacer I cut on my lathe....but you can just use quarters. |
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Quoted: I have posted this many times and probably just need to update my website for this but here it is again. 1. I try to do all my tuning in the upper. So for a gas operated setup, it is 'gassed' the way I want it. More on that later. For a factory setup typical gassed 16" midlength, do you think 'the amphibian' (Tubb+Kynshot+A5) will still make a noticeable difference w/ FRT? And if I'm not yet ready to switch to an A5 tube, do you think the regular Carbine Kynshot is worth it, or not enough effect? I'm trying to lower RPM, but mostly looking to reduce bolt impact effect to improve accuracy when standing out to 25-50yd. |
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Quoted: For a factory setup typical gassed 16" midlength, do you think 'the amphibian' (Tubb+Kynshot+A5) will still make a noticeable difference w/ FRT? Quoted: For a factory setup typical gassed 16" midlength, do you think 'the amphibian' (Tubb+Kynshot+A5) will still make a noticeable difference w/ FRT? Bear in mind, I have also always said that tuning the gas is #1. If your setup is grossly overgassed no buffer or spring will make much difference. The buffer system is for fine tuning assuming your upper isn't overgassed. And if I'm not yet ready to switch to an A5 tube, do you think the regular Carbine Kynshot is worth it, or not enough effect? I'm trying to lower RPM, but mostly looking to reduce bolt impact effect to improve accuracy when standing out to 25-50yd |
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Quoted: Yes - I've been running amphibian's setup since mid 2020 on one of my M16's. Since I've got a couple PSA stores in my area I use one of their 308 buffer tubes. Maybe we should nickname it the "ARS" for Amphibian Recoil System. |
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Quoted: I think I came up with that combo and have been posting about it since around 2017. https://c3junkie.com/?page_id=977 Guess I'm a day late and a dollar short...again. |
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Quoted: Compared to what buffer setup? Bear in mind, I have also always said that tuning the gas is #1. If your setup is grossly overgassed no buffer or spring will make much difference. The buffer system is for fine tuning assuming your upper isn't overgassed. If you read all the testing I did in this link: https://c3junkie.com/?page_id=1733 which is for 9mm but same idea of trying to reduce reciprocating mass is mentioned. I tried to use the RB5004 but that didn't work out. Then the RB5005 which I have recommended if you didn't want to go with the A5. After all that, I still go back to the heavier RB5007 for the best impulse. Why? I think it is because as you can see in the high speed video I posted above that upon the initial recoil impulse you can see that the mass of the buffer body moves forward to reduce that impulse. This is shown in the Kynshot animations and then I show the same thing with live fire. You have less mass doing that with the lighter RB5004, RB5005 or other carbine hydraulics. Quoted: Quoted: For a factory setup typical gassed 16" midlength, do you think 'the amphibian' (Tubb+Kynshot+A5) will still make a noticeable difference w/ FRT? Bear in mind, I have also always said that tuning the gas is #1. If your setup is grossly overgassed no buffer or spring will make much difference. The buffer system is for fine tuning assuming your upper isn't overgassed. And if I'm not yet ready to switch to an A5 tube, do you think the regular Carbine Kynshot is worth it, or not enough effect? I'm trying to lower RPM, but mostly looking to reduce bolt impact effect to improve accuracy when standing out to 25-50yd Thank you for all the info. I'm currently using the factory H2 buffer, I'd say ~900rpm, good ejection pattern. Reticle bounce through 4x ACOG is good, not bouncy, but even with a compensator I can only consistently keep 2rd salvos on a small (9"x14") torso target at 25yd standing. I suspect the rapid cumulative bolt impacts are driving me off target. Hoping to get to a more controllable setup for target shooting/hosing. |
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