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Posted: 4/1/2026 3:20:02 PM EDT
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I’m in the very early stages of prototyping out some heat sinks for .980 Hbar barrels being used for the L6 and standard IAR uppers. Started out as a one off for just me but there’s been some interest from a handful of other shooters. Here’s the first article before and after a range trip, we did one 220 and one 250 round cyclic mag dumps with a 100rnd drum, then 2 60s and a 30. Chambered a round then waited 5 minutes, surprisingly no cookoffs. I’m going to be checking cross compatibility with different barrels and handguards shortly. Attached File Attached File Attached File |
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| Pretty tame, warm but with gloves it was more than bearable. I undersized the OD to be lightly touching the ID of that yhm quad rail so once it’s anodized and hot it’ll have contact and add contact radiation as well as adding to the overall thermal mass. A full size forward grip with a metallic attachment point is advised 😅. I’m going to be doing some 300-500 round cyclic testing once I have the v2 model done, hopefully with a thermal camera and laser thermometer. I want to find the delayed cook off point, more as a round count and less at a set temp. I’m going to tinker with including some tellurium copper sections closest to the chamber as well. I have about 20 barrels and 12ish handguards already picked out to order and check compatibility. Overall pretty impressived. I have two twin barrels, one for the L6 that got delivered, and the other pictured here, so side by side testing should give some consistent data to share. |
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| Ideally I’d like to run small batches to sell if there’s enough interest. Once I can give out some solid data and compatibility I’ll move forward a little more seriously. Lots of hoops to jump through to get there, getting quotes from an anodizer is like pulling teeth so far and building my own anodizing set up is equally difficult. But the design and material makes them cheap and easy to make. The goal is to have something to offer 3rd quarter of this year so we’ll see. |
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| Yes, and that’s been brought up by several people. I can either reduce the OD of the heat sinks or recommend one of the larger ID handguards that would ensure free float is maintained. There’s a mixed bucket of opinions, but for me personally the accuracy difference of free float and non free float is negligible when I’m throwing rounds down range at 800-900rpm, But I get the concern for sure. And in either case the accuracy potential is better than any open bolt counterpart. My goal was to maximize thermal efficiency, handguards tend to act as a pseudo heat trap in some ways so I decided why not add it directly to the thermal mass and surface area to maybe increase efficiency. Either way it’s getting hot and gloves and accessories will need to be configured accordingly. |
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Cody makes good stuff! Hopefully on par with his RPD radials, our mass and geometry are fairly similar although I’m not 100% sure what his retention method is. I’ve been told he uses thermal paste, but they might be heat or slip fit. My notched radials utilize an undersized ID and require snap ring pliers to open and work them into place where they’re retained very snug under tension. Short of building custom whole uppers it was the best user friendly design I could come up with. My goal is to also offer a hybrid stack with some copper sections to be used nearest the chamber to draw heat off significantly faster than the T6 and individual sections so users can configure the stack as they see fit. This would give a little more handguard options and most of those are already compatible with the L6. |
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These are individual discs cut on a cnc laser. I’m slightly worried under extreme heat they might open up or loose tension but so far that has not been the case. It makes them very cheap and quick to make, and with minor effort I can adjust the program to accommodate slight barrel tapers or different diameters. Attached File |
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Originally Posted By CharlieArms: Pretty tame, warm but with gloves it was more than bearable. I undersized the OD to be lightly touching the ID of that yhm quad rail so once it’s anodized and hot it’ll have contact and add contact radiation as well as adding to the overall thermal mass. A full size forward grip with a metallic attachment point is advised 😅. I’m going to be doing some 300-500 round cyclic testing once I have the v2 model done, hopefully with a thermal camera and laser thermometer. I want to find the delayed cook off point, more as a round count and less at a set temp. I’m going to tinker with including some tellurium copper sections closest to the chamber as well. I have about 20 barrels and 12ish handguards already picked out to order and check compatibility. Overall pretty impressived. I have two twin barrels, one for the L6 that got delivered, and the other pictured here, so side by side testing should give some consistent data to share. Don't forget, you will loose thermal transfer when anodized. Anodizing is a decently good insulator. Heat will also discolor anodizing and will even eventually turn black hard ano into a lighter or purple/brown color. |
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Originally Posted By Deerhurst: Don't forget, you will loose thermal transfer when anodized. Anodizing is a decently good insulator. Heat will also discolor anodizing and will even eventually turn black hard ano into a lighter or purple/brown color. While it does slightly reduce the ability for thermal conduction (it's honestly negligible in the end), it massively improves thermal radiation. I'd be more concerned with the potential for galvanic corrosion over time with raw aluminum. |
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| Bingo, type 2 is pretty forgiving, it’s a balance of the oxide layer (.001+/-) insulating the heat coming off the barrel from the aluminum, and the aluminum now having a greater radiative conductivity. In the end cosmetic demand will be the main reason, although I’m happy to offer a raw or blasted/tumbled finish at a decent discount if there’s demand. Either way 6061-t6 is around 3-4x more thermally conductive than 4150, the copper sheet I’m hopefully going to use is 8-9x more efficient. So while it adds weight, it should give any IAR an edge worth the hassle. |
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Attached File Some new test parts, c110 copper and 6061-t6 aluminum for L6 specific configurations and .975-.980 Hbar barrels. Found an anodizer and I’m sending a batch soon for type 2 black and then off to testers in the wild. |
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Attached File Attached File Attached File Test fitment looks great! Once anodizing and copper oxidizing is done I’ll have have some finished sets to demo on YT and IG. The L6 set up won’t be ready until my builder kit gets in at the end of May. I’ve compiled a list of in production handguards and barrels that should be compatible and I’ll check and document all of them so there will be less guessing on the consumer end. I can’t promise any timelines yet, but once production models are ready, heat testing is done and I get some feedback back from other test users, these should be ready to rock and roll. So if you’ve been wanting a heat sink for your LSW, hope we can deliver. |
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Originally Posted By Jeeps-And-Guns: Make it flow through like a Lewis gun. Self cooling. Haha I’ve been pitched that idea a few times, maybe down the road I could try it with a tubular handguard and muzzle device, if the relief cuts and holes were made correctly, you could in theory utilize the exiting gasses to create a flow/venturi effect with every shot. Unfortunately it would be ugly, expensive, and probably wouldn’t sell well, but I’m game to try if I can get it working. |
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This project is still underway, I took the last two months to buy about a 20 different barrels and a dozen different handguard to check compatibility of my parts. After that, we found out a bit of a big design flaw in some heat testing. Unfortunately, the undersize/spring tension fit will not work unless it’s a closed ring because once the aluminum and copper get hot enough, they lose tensile strength and will thermally decouple, and then not shrink to the same tension as before, so eventually the system will become less and less efficient. I can still use all the geometry and data I have up until this point, but I can only use a smaller selection of barrels that will work with a heat fit. It’ll be slightly more complicated of an install, but still doable for most guys with a cooler, acetone, dry ice, and an oven. I’ve also been delaying the rest of the development until I have a good host, but my L6 kit seems to be taking forever :/. Right now, my primary barrel selection will be the KAK L6 barrels, KAK OE spec barrels, Small Team Supply RPK barrels, and the FN produced cold hammer forged barrel sold by spikes tactical. |
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| I did a few cyclic tests over the last few months, but I’ve been holding off on getting hard data until the designs finalized. I’m going to build two twin uppers, one with and one without the heat sink so I can run cyclic, burn down style tests and get a thermal conductivity comparison. |
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Just seeing this thread. This is awesome. For your consideration (and admittedly not for belt-fed uppers). Have you looked into making a heat sink for non-belt-fed AR's? I've been digging around for ideas for a home brew IAR, and the VLTOR CASV handguard (carbine and midlength) have a ton of room inside with 1.8" I.D. and I feel would make great candidate for this use case. The bottom of the handguard also detaches easily for maintenance. It may be worth looking into. |
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