Home AR-15 Product Spotlight: Brownells BRN-4 Upper Receiver Kit

Product Spotlight: Brownells BRN-4 Upper Receiver Kit

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Steve and Caleb are a little jazzed today because they’re giving us a tour of the new HK416-compatible Brownells BRN-4 piston upper receiver kit. The BRN-4 is built to HK416 specs, so it’ll work with any 416 components either original or aftermarket like the new ones Brownells will be releasing in the near future. More good news: the BRN-4 fits on a standard mil-spec AR-15 lower receiver, so you can build up an HK416-type rifle without encountering the scarcity and very high cost of original 416 parts. Or maybe you bought up some of the genuine Heckler & Koch surplus HK416 components we sold a few years ago? They’ll work with this upper.

The BRN-4’s free-floating quad-railed handguard is keyed to the front of the receiver, so it can’t shift or twist on the barrel nut. Removing the ‘guard reveals the H&K-type short-stroke piston operating system. A common problem with putting a piston system in an AR-15 is “bolt tilt,” which leads to excess wear on the receiver extension (aka “buffer tube”). The H&K bolt-carrier design eliminates the tilt, thus eliminating unwelcome wear-n-tear on the buffer tube.

The BRN-4 upper is called a “kit” because it comes disassembled. If you can assemble an AR-15 upper from parts, you’ve got the skills to build a BRN-4. It does not include a muzzle device, but the barrel has standard ½”-28 tpi threads, so any AR-15 flash suppressor or compensator is fair game.

If you’re an AR-15 collector or just want to build a sweet, high-tech PISTON-operated AR-type rifle that’s extremely reliable and still compatible with a gazillion AR-15 accessories…… the Brownells BRN-4 is for you!

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49 COMMENTS

  1. I love everything you guys (Brownelles) are doing, making/manufacturing, and offering for AR lovers and builders. The BRN-180 and the new BRN-4 are amazing and fun pistols/rifles. If only the 180 was just under $1,000. $1,500 for the BRN-4 upper is to much. If you can afford to spend $1500 on just an upper then you can afford a complete 416 kit.

  2. Wonderful birthday news. I look forward to this time next november when, knowing brownells, they finally announce the long-awaited restock of these parts/kits and I might possibly get my hands on one along with some aluma-hyde II I've been haunting the store page of for about five months now!

  3. 3:45 "the reason they do that is because there's no gas rings to add friction." The gas rings don't "add friction", they allow the gas to push the bolt forward while it's unlocking to reduce friction between the bolt and barrel extension. That's the effect H&K is trying to replicate with the spring between bolt and carrier. Someone teach this guy how an AR-15 works.

  4. BRN 4 complete kit runs $1500 right now. Not that bad. Hopefully it comes down a bit for Xmas. Larry Vickers worked for HK and was on the HK team that designed the 416. I think his design has a barrel that was only partially chromed, but not 100% sure. Anyway, excellent platform. Don't need the snide remarks aimed at Steve tho – re one syllable words.

  5. You should update the stock status I ordered one only to get an email that they are not in stock nor may never be again. I didnt realize brownells adopted the optics planet model of coercing people into ordering products that are out of stock or do not exist.

  6. Where are the tests? Stop having people beta test things and show the tests done. Grab thousands of rounds, run it in a video then show us these things can run… Transparency…

  7. Nice but the gas block is for a non-adjustable HK416 as compared to the adjustable gas block on the HK416-A5. I don’t know how these uppers will function when a suppressor is attached.🤔🫣🫤🎲🎲🤷🏻‍♂️🤦🏻‍♂️

  8. I got to admit. I’ve shot a gas piston AR. I’m not a big fan. I feel that the direct impingement is more accurate due to less mass moving reward. Also it seemed more prone to carbon fouling issues. The rifle was not mine. I was asked to take it to the range because the owner had some failures with it. So I did. After 10 rounds it had a failure to eject. Extraction seemed fine. I felt like the bolt did not fully cycle backwards enough. I took the rifle home and cleaned it and scrapped built up carbon off the gas piston. The owner was using Wolf ammunition. After I cleaned it. I took it back to the range and shot it with Federal ammunition. No issues at all. I brought it back home. Cleaned and lubed it with CLP. I advised the owner to stay away from Wolf ammunition. That’s been my only experience with the gas piston AR’s.

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