{"id":4049,"date":"2024-06-15T06:14:03","date_gmt":"2024-06-15T06:14:03","guid":{"rendered":"https:\/\/firearmman.com\/?p=4049"},"modified":"2024-06-15T06:14:03","modified_gmt":"2024-06-15T06:14:03","slug":"brownells-733-upper-receiver-the-firearm-blog","status":"publish","type":"post","link":"https:\/\/firearmman.com\/?p=4049","title":{"rendered":"Brownells 733 Upper Receiver -The Firearm Blog"},"content":{"rendered":"


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Brownells, in large part, started the retro resurgence of the last few years. While they did get out of the game with complete guns, they still offer parts and uppers. The most recent batch of uppers is more modern and includes the Brownells 733, a Model 733 clone<\/a>. Yes, the 733 we all know and love from the movie Heat. When Brownells offered me a review of this upper, I promptly sent them my shipping info and I started loading magazines.<\/p>\n

Brownells @ TFB:<\/strong><\/p>\n

Disclosures are important in any review so the audience has all the facts. Brownells reached out to me and offered to give me the upper. Being a fan of carry handles generally and the movie Heat in particular, I said yes to that offer. I paid for the ammo.<\/em><\/p>\n

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733 upper on post-sample lower.<\/p>\n<\/div>\n

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Design<\/h2>\n

The 733 upper is built around a C7 receiver. That is a variant of the A1, but it adds the newer A2-style brass deflector. The rear sight is still a standard A1 model with two apertures in the rear sight. The long-range aperture is marked with an \u201cL\u201d as would be expected.<\/p>\n

Just like the original 733, the Brownells version has a lightweight, chrome-lined 11.5-inch barrel. This one is made by Luth-AR. In keeping with the A1 theme, the flash hider is an A1-style birdcage with slots around the entire circumference. This is different than the far more common A2 flash hider, which has a closed underside to reduce the amount of dust it kicks up.<\/p>\n

One point to note is that the Brownells 733 upper does not have M4 feed ramps. Those are standard these days because they do help with reliability, but they would not be \u201cclone correct\u201d on this gun.\u00a0Another throwback feature is the teardrop forward assist. It functions just the same as a regular round forward assist but has more surface area.<\/p>\n

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Brownells 733 upper, right side.<\/p>\n<\/div>\n

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Brownells 733 upper, left side.<\/p>\n<\/div>\n

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The long-range aperture is marked with a capital \u201cL\u201d.<\/p>\n<\/div>\n

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No M-4 feed ramps here, but it still runs fine with all types of ammo tested.<\/p>\n<\/div>\n

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On The Range<\/h2>\n

I broke in the 733 upper in the only way that seemed appropriate: on a post-sample machinegun lower. It\u2019s what Neil McCauley would have wanted. I put about 150 rounds through it in the first outing, ranging from 55-grain factory ammo to 77-grain reloads. My dad happened by the shooting range while I was shooting full-auto, and he took a turn. This setup put the biggest smile I\u2019ve seen on his face in a long time.<\/p>\n

I had so much fun shooting it as a matching gun that I did quite a lot of it. For the most part, it was just good, uneventful fun. The only warning sign came when I dumped a solid 60-round burst from an ATI\/Schmeisser quad stack magazine. The gun was already warm when I started, and after that extended run at the cyclic rate, the gas tube was glowing red. When it finally cooled off it had some obvious heat-related color changes, but it continued to function just fine.<\/p>\n

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The gas tube glowing red near the gas block. Also, note the smoke coming off of the barrel by the FSB.<\/p>\n<\/div>\n

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Once the gas tube cooled off it turned a purple\/blue color gradient.<\/p>\n<\/div>\n

The lack of M4 feed ramps was not an issue at all, regardless of ammo. I used everything from cheap .223 Remington FMJ ammo up to 77-grain boat tail hollow points and everything ran without a hitch. Feeding was also flawless across a wide range of magazines including Duramag, Magpul, Amend2, Hera Arms, FAB Defense, and Okay Surefeed models.<\/p>\n

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Some of the test magazines (L to R): Hera Arms, Amend2, FAB Defense, Okay Surefeed, Duramag.<\/p>\n<\/div>\n

Carry handle uppers are not always the best hosts for optics, but I tried a few optics on the mounting hole. I used my trusty old Trijicon reflex sight and the Primary Arms 3x Micro Prism<\/a> at various times. Both worked well, but the vibes from the Trijicon were unmatched.<\/p>\n

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Primary Arms SLx 3x Micro Prism.<\/p>\n<\/div>\n

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Trijicon Reflex Sight on a gooseneck mount on the 733.<\/p>\n<\/div>\n

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Another accessory I used was the SilencerCo Omega 300 mounted with the Griffin Armament A2 mount<\/a>. Though it says A2 in the name, it also worked with the A1 flash hider on this upper. It functioned fine but ran just about how you would expect any short barrel direct impingement 5.56 to run as far as back pressure.<\/p>\n

Velocity Testing<\/h2>\n

Short barrels trade velocity for maneuverability. But just how much do they lose? That varies a lot depending on just how short it is and what ammunition is used. I tried a bunch of loads and gathered velocity info with my Garmin Xero C1 chronograph.<\/p>\n