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Posted: 6/18/2026 5:29:17 PM EDT
| I added a new FRT to my 10.5" AR15 Pistol (PSA build kit) with folding stock. Both H1 and H2 buffers resulted in light primer strikes. When I moved up to H3, the gun would cycle approximately 3 rounds and then jam... any idea of the diagnosis flow I should use to get this thing operating reliably? |
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Make sure you aren't using a heavy spring, and make sure you are using a TRUE H3 buffer. Yes, there are companies that make buffers that say H3 on them, but they are NOT true H3 buffers... It needs more than just a weight of ~5.6 oz. - it needs RECIPROCATING WEIGHTS, and in the proper percentage of total weight. Here is a good H3 with Tungsten weights: https://kakindustry.com/buffer-h3-5-6-oz-carbine-satin-gold-anodize/ https://www.youtube.com/watch?v=2SStS9gPeWc This video is about 9mm buffers, but the same principles apply to all AR buffers. Take your buffer apart and verify there are three 1-1/2 oz. reciprocating tungsten weights inside. Tungsten has gotten so expensive lately, it is hard to find, and when you do, it is painful to buy! If you recently bought an H3 for ~ $40 or so, you probably have a FAKE H3. You can use a strong magnet to get a good idea of what is in there, assuming the body is not steel. A magnet will attract steel really well, tungsten a little, and not attract aluminum. If it DOES HAVE a steel body, I expect your buffer to be a FAKE H3 buffer, unless it is a Tromix. (And it probably isn't a Tromix or you would have already said so...) I have not used a Tromix myself, but posters on this web page have verified it works well, and quite a bit cheaper than something that contains three 1-1/2 oz. tungsten weights, like the KAK buffer I linked to above. https://tromix.com/product/ar-15-h3-buffer-carbine/ Edited to add: You didn't say what FRT you are using, or what caliber. That information would be helpful in order to help you! |
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Originally Posted By BluewaterPatriot: and then jam... any idea of the diagnosis flow I should use to get this thing operating reliably? Identify your problem. Jam could describe a number of different stoppages. Oddball for me is: "folder". Tell us what sort of device? Chambering: You say 300 Blackout - it matters. Load: It matters. What ammo? FRT. Which one? Buffer: which H3? It absolutely needs an effective deadblow. If it's aluminum bodied, rattles if you shake it, and weighs ~5.4-5 ... it's good. Pics help. |
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I put a Partisan into my friend's Del-ton AR15. We tried it with an H1 buffer = 1 shot dead trigger in FRT mode. I grabbed an H3 buffer and put it in his gun. Still was having issues. I noted his buffer spring was shorter than mine and pulled a longer buffer spring out of one of my other AR's. Fixed it - runs perfectly now. |
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Originally Posted By drobs: I put a Partisan into my friend's Del-ton AR15. We tried it with an H1 buffer = 1 shot dead trigger in FRT mode. I grabbed an H3 buffer and put it in his gun. Still was having issues. I noted his buffer spring was shorter than mine and pulled a longer buffer spring out of one of my other AR's. Fixed it - runs perfectly now. Very good. I don't suppose you have any idea who made that spring? |
It was not preached to the crowd,
It was not taught by the State.
No man spoke it aloud,
When the English began to hate.
It was not taught by the State.
No man spoke it aloud,
When the English began to hate.
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Originally Posted By getchevyn: Had the same issues with a Rare Breed and Disruptor in separate 10.5" SBRs. Ordered the Geissele H3 buffer with the Super 42 braided spring kit when it was on sale a couple weeks ago. Took it out to the range today and both rifles preform flawlessly. If I am reading this correctly, the issue was bolt-bounce causing the light primer strikes & it was solved with a heavier buffer + stiffer spring? |
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Originally Posted By bravo5two: If I am reading this correctly, the issue was bolt-bounce causing the light primer strikes & it was solved with a heavier buffer + stiffer spring? Yes. That's what I believe cause my issues and the higher quality buffer + definitely the stiffer spring solved it. I was using a H3 buffer before this on my LMT 10.5 uppers and getting light primer strikes after 1-3 rounds. It was completely solved with the new parts. |
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Joined:
Dec 2023
Posts:
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EE: 100% (7)
USA
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Originally Posted By getchevyn: Yes. That's what I believe cause my issues and the higher quality buffer + definitely the stiffer spring solved it. I was using a H3 buffer before this on my LMT 10.5 uppers and getting light primer strikes after 1-3 rounds. It was completely solved with the new parts. Originally Posted By getchevyn: Originally Posted By bravo5two: If I am reading this correctly, the issue was bolt-bounce causing the light primer strikes & it was solved with a heavier buffer + stiffer spring? Yes. That's what I believe cause my issues and the higher quality buffer + definitely the stiffer spring solved it. I was using a H3 buffer before this on my LMT 10.5 uppers and getting light primer strikes after 1-3 rounds. It was completely solved with the new parts. Just remember, in general a stiffer spring will exacerbate carrier bounce. It's good that the buffer is able to compensate, but keep it in mind for future builds. |
It was not preached to the crowd,
It was not taught by the State.
No man spoke it aloud,
When the English began to hate.
It was not taught by the State.
No man spoke it aloud,
When the English began to hate.
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