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Posted: 7/7/2026 11:56:43 AM EDT
[Last Edit: AmericanInfidel][Edited]
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Sorry for the wall of text, but maybe one of you guys has an idea I'm missing. I put a SS kit from Trigger-Man in a lower with standard carbine spring and Spikes H2 buffer. Upper is a home build from some small gun shop, slick-side receiver, Wilson Combat 16" barrel, Fail Zero bolt, mid-length gas with Superlative Arms adjustable block. It started with a mil-spec gas block and semi-BCG, the full BCG and new gas block were added by me. As it is, there is one (position 10 out of 17 IIRC) position on the adjustable gas block that allows for two super-safe rounds before a dead trigger. Hammer down, light primer strike. To get this far, besides replacing the gas block/tube and BCG, I have filed out the back of the upper receiver to make clearance for the SS lever, added M4 cuts to the upper receiver to match the barrel, and tried multiple stength buffer springs and different weight buffers in all kinds of configurations, as well as swapping in lower parts from other guns that I know just work. I think I have it narrowed down to the upper, as the new SS lower will run two other uppers, one supressed piston upper and the other is a factory Colt 6920, both of those uppers have their own lowers with FRT that runs fine, so I tried the new upper on the tried-and-true lowers, still no more than two shots. Could the gas block be out of spec and cause this? I'm about out of ideas for this upper. Help me Arfcom, you're my only hope. Update: I picked up a Tromix H3 this morning, opened the gas block one more click, and we're up and running! That Tromix buffer is some kind of magic. |
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Originally Posted By Mav3rick: I am indeed not any kind of expert, and l may be completely off in this suggestion, but I thought l remember reading about problems with frts and spikes buffers due to spikes using tungsten powder and not an actual freely moving weight in their buffers. I also tried a carbine buffer and an H3+ using an Odin Works adjustable buffer. Think one of the Tromix buffers being discussed here might do the trick? |
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Originally Posted By AmericanInfidel: I also tried a carbine buffer and an H3+ using an Odin Works adjustable buffer. Think one of the Tromix buffers being discussed here might do the trick? If by H3+, you're describing an Odin Works "Heavy" - that one does not brrrrrt. Tromix are known to brrt, so you may be on to something. You describe a common failure caused by a buffer failing to mitigate bolt bounce. With an AGB, you should be able to tune out enough gas to run with a proper H2. But you also describe an AGB that is not doing adjustments properly. Your buffer needs to maximize sliding weight v. total weight. This is why the steel Odin Heavy fails to mitigate bounce. |
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Originally Posted By HKPDW: I’d look at the Superlative Arms adjustable gas block. Like you said, there are 17 settings. I’d also consider an H3 buffer. The Superlative block seems to work okay, with it off the gun it does a good job of restricting air flow, with it on the gun it will restrict gas enough to keep the bolt from chambering a round until opened to position 5. Once cycling, it starts ejecting brass around 5:00, by position 10 it throws brass from 3:00-4:00, wide open it throws brass from 2:00 to 3:00. So, I can tell it adjusts, but if the gas port is out of spec could it be keeping it from getting what it needs? I wonder about that because it runs two rounds at position 10, but more gas and its back to single fire. FWIW, ejection pattern was 2:00-3:00 with the mil-spec gas block, and shot semi with dead trigger and hammer down in SS position. |
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Originally Posted By dredeagle: If by H3+, you're describing an Odin Works "Heavy" - that one does not brrrrrt. Tromix are known to brrt, so you may be on to something. You describe a common failure caused by a buffer failing to mitigate bolt bounce. With an AGB, you should be able to tune out enough gas to run with a proper H2. But you also describe an AGB that is not doing adjustments properly. Your buffer needs to maximize sliding weight v. total weight. This is why the steel Odin Heavy fails to mitigate bounce. I know the Odin gets (deserved) hate, but they go brrrr just fine...I am sure they will not fix a bolt bounce issue, but IME if you don't have a particular issue they will not introduce it. At least on a 5.56. I am sure 9mm is a different ballgame. Not an endorsement, a decent G$ H3 or similar (or Tromix if needed) is the jam for these...but the Odins go brrr real well from the few I have seen (again though, they were not trying to solve an existing bounce issue). But so does everything. Spikes/Odin/unknown/any dead blow H3 weight or better buffer will run 100% ime (I do know if is not that simple for everybody). The only ones I have not seen used are the JP captured type and lighter carbine buffers (H2 is often fine OFC). And my Odin Heavy has Tungsten...maybe just one though. Now that I think of it, when I took one apart yesterday there were 2 tungsten weights in it...so I may have cannibalized one from another buffer. Sliding weight vs total weight...is that why the spikes I have had a very very light alloy body, they are trying to increase that ratio? I guess that makes sense. I am pretty hype on KAKs frt BCG. Hell yes. Especially for 9mm and PDW (maxim/sbpdw) short buffer tube/buffer setups. |
| The Odin heavy has two tungsten weights and one stainless weight, it goes brrrt with a super safety in a 6920 both supressed and unsupressed, also in a suppressed Adams piston upper, and also in a LaRue upper, just not in this particular upper build. It does seem like something about it is causing bolt bounce. I found a shop local with a Tromix H3 on the shelf, I'll head out there tomorrow, see what happens with this buffer and report back. |
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Originally Posted By bionicmonkey: Contrary to the post above - the odin heavy does not brrrt. Get a regular H3 - or better yet the gieselle super 42 spring and h3 set. Lmao... Of course it does. H2 or lighter will run in many setups (lots of people happily running whatever came in the gun), but sometimes you run into bolt bounce so most of us run H3s or better. That is not a FRT requirement, it is a safe recommendation to cover most all setups, it is going to be different gun-to-gun. Neither it or a H2 will solve any bolt bounce issues, and in some setups (probably a lot) they will introduce it...or allow it to present rather, so stick with a H3 as best practice, but the H3 is a safe bet, not the bare minimum needed to make it possible for the gun to run. But I addressed this all in my above post, and am also a big fan of G$ H3/Super 42. Here is the Odin Heavy with whatever no-name spring I grabbed...sure is cold out here.  https://rumble.com/v7ci2hu-bby-go-brrr.html And here is last round ignition and BHO: https://rumble.com/v7aa34m-i-really-cant-stay.html So when I post that ""hey, I see that most people here hate them, but they go brrr just fine for me, and you reply "nope, nope they don't, don't listen to him lalalala"...eat my friggin' shorts brah. I do know what I am talking about. A little. Bounce isn't a yes or no thing, all bolts bounce just like all barrels whip, sometimes it is excessive. A heavy barrel will bounce the bolt back harder than a pencil barrel, if the recoil spring is too heavy it will bounce more, etc etc. |
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Originally Posted By BKenton: Here is the Odin Heavy with whatever no-name spring I grabbed...sure is cold out here. https://rumble.com/v7ci2hu-bby-go-brrr.html And here is last round ignition and BHO: https://rumble.com/v7aa34m-i-really-cant-stay.html I'm glad that worked for you. My experience was very different with Odin Heavies. For me, they failed to mitigate bolt bounce in two 7.62x39 builds. Both builds go fast with Standard 3 sliding tungsten H3s and with Tromix H3s. The Odin Heavy experiment did give me a good start on my tungsten weight collection. |
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Originally Posted By dredeagle: I'm glad that worked for you. My experience was very different with Odin Heavies. For me, they failed to mitigate bolt bounce in two 7.62x39 builds. Both builds go fast with Standard 3 sliding tungsten H3s and with Tromix H3s. The Odin Heavy experiment did give me a good start on my tungsten weight collection. Im not glad or sad about it. It’s just a thing that is. If it did not work for you…I’m gonna assume it may not have worked for you. This seems common. Like I said, it’s not going to cure any bounce issues you might have…but it’s going to work fine much of the time. |
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