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Posted: 6/15/2026 9:14:18 PM EDT
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I’ve got a couple of barrels with undersized gas block journals. One is .747, and the other is .7460. Out of nine gas blocks, I can’t even come close to one fitting. Heck, I can shake them side to side on the barrel. Does anyone make an undersized gas block? I have no problem opening a smaller one up. I really don’t want to epoxy or shim. I appreciate any help. |
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Originally Posted By FRONTIER: I’ve got a couple of barrels with undersized gas block journals. One is .747, and the other is .7460. Out of nine gas blocks, I can’t even come close to one fitting. Heck, I can shake them side to side on the barrel. Does anyone make an undersized gas block? I have no problem opening a smaller one up. I really don’t want to epoxy or shim. I appreciate any help. Reamers are cheap on Amazon . It's not for production, so you'll be OK. Perhaps, tell us who made this undersized junk ? |
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This one might do the trick. It has high temp o-rings on each end that might tighten up the fit for you. https://www.ripcordindustries.com/product-page/epa-750-gas-block |
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Possible candidate HERE (No personal experience/nor idea what the actual dimensions are). |
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Thank y’all for the suggestions. I may try both just to see how they work out. The worst one is a 12.5 IWI mid gas barrel. It looks new or barely fired. I believe I picked it up in the EE years ago. I prefer not to name the other as It’s not that big of deal. It’s from a good manufacturer that I have never heard a complaint about. I haven’t notified them of it and I will take care of it myself. Thanks again. |
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I would try a clamp on style gas block. https://yhm.net/accessories/gas-blocks/low-profile-gas-block-clamp-screw/ |
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I just put a CMMG adjustable gas block on a Cerakoted Satern Liberty barrel. I had to hammer it on. Granted, the Cerakote added some thickness, but the block seemed undersized to me compared to anything else I've used. Also, have you tried tightening the block down and shooting the gun to see if it works? If it works, I'm not sure it matters how tight the block hugs the barrel. Loctite 620 is an option too. It's not an epoxy, but it's designed to fill gaps in cylindrical fittings. |
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Using HV insulated copper wire, wrap the wire around the gas blocks axially to create a gas-block-in-a-solenoid. Now using a HV capacitor bank and a spark gap trigger, trigger the capacitor bank discharge through the solenoid. Think like 22kV @ 7kJ capability for the cap bank sizing. When you fire the capacitor bank through the coil, if the Lorentz forces are great enough they will shrink the gas block (circumferentially) little by little. But start at like 10% power and work your way up… it would suck to overshrink the gas block on the first go. Do it behind cover / blast shield. Post vids. Don’t die. |
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Don't do what OhioMan suggested unless you know what you are doing with HV electricity and already have most of the equipment for what he suggested. As someone with years of experience working with HV electricity, while what he suggests is absolutely generally feasible, the plan has flaws and if you make one mistake with what you're doing you could electrocute yourself to death or get yourself impaled by shrapnel. Yes, crushing things with Lorentz forces is really neat. But don't fuck with HV electricity unless you know what you're doing. Safety first. It's like firearms -- learn WTF you're doing and know and follow safety rules, because death is a consequence. You need to know (calculate) the forces you are generating to know how much shrinkage of the gas block to expect, and the force of the explosion of the coil of electrical wireto make sure you have adequate shielding for that blast. But, the flaw with the plan is that it would also shrink the gas tube opening, gas tube pin hole, and any screw holes, so the gas tube and it's pin wouldn't fit and neither would any screws. You'd need to re-drill or mill all those holes and re-tap the threaded set screw holes, which would also strip any protective coatings the gas block came with. Additionally, some surface treatments that harden the surface may result in unexpected cracking or geometry changes. You also run the potential to crush the sides of the block in, but not affect the more solid upper part of the gas block. And good god, I have a rant if you are suggesting doing this with it installed on the barrel. |
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