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All of the Benefits of Short Barrel Uppers in One Place

All of the Benefits of Short Barrel Uppers in One Place

Posted by MCS GEAR UP on Jul 10th 2024

Thinking about building an SBR or an AR pistol with a short barrel upper such as a 7.5” upper? You’re in the right place.

But in case you needed any justification, here are just about all of the draws of building with a short upper.


You can flute a barrel, and that will reduce weight and mass, but that will only take you so far. Shortening the barrel’s overall length is the best sure-fire way to reduce weight and mass. AR pistols and SBRs are just lighter than full-sized AR rifles, period.

Compact Footprint

Shortening the barrel is just one piece of the equation. There are short buffer systems you can get to reduce the length even further, creating a smaller, more compact platform that is easier to conceal, handles better, and is ideal as a truck gun or a defensive platform.

Improved Concealability 

                      short buffer systems

Given the smaller nature of short barrel uppers and the SBRs and AR pistols constructed from them, they are much easier to conceal, making them easier to transport as well.

Better Maneuverability in Tight Spaces

Carbine-length AR platforms with 16” barrels are good, but you can’t beat a true SBR or AR pistol when it comes to CQB. They are lighter, faster handling, and just overall more agile than larger, heavier variants. This makes them ideal for defensive applications, especially in tight quarters.

Short Uppers Are Still Available in Rifle Calibers

If you thought you’d need to forfeit your 5.56, 7.62 Soviet, or .300 BLK in order to build with a short barrel upper, think again. One of the most attractive features of all is that you can get rifle-caliber power in a smaller, more compact package with a short barrel upper, or even an AR pistol, enabling you to bring more firepower in a pocket-sized footprint.

Potentially Improved Barrel Harmonics

Bet you thought you’d have to sacrifice accuracy by shortening the length of the barrel, didn’t you? That wouldn’t necessarily be correct, though. In fact, a shorter barrel has the potential to improve accuracy.

A short explanation is needed, since it is often assumed that a longer barrel is more accurate. This is sometimes the case, because a longer barrel gives the bullet more time to engage the rifling before leaving the muzzle. However, this is not the entire picture.

It is also true that longer barrels exhibit more whip and can produce less consistent barrel harmonics. If that is the case, barrel whip can actually throw bullets slightly off the point of aim, confounding accuracy. So it is sometimes the case (and in the absence of a barrel tuner) that shorter barrels are actually more accurate.

Either way, they are not necessarily less accurate, which in and of itself is a solid selling point for short-barreled rifles.

Better Overall Footprint When Running Suppressed

Another great thing about building an SBR with a short barrel upper is that if you plan to run it suppressed, it’ll handle better.

The truth is that suppressors can be large, unwieldy, and sometimes even heavy. A suppressor, even on a carbine-length platform, can handle a bit clunkily, to say the least.

By contrast, running a suppressor on a short-barreled rifle is much more practical and will handle more like a carbine.

Another thing to consider here is that the shorter the barrel, the worse the muzzle pop, so it makes even more sense to install a suppressor.

Assembled Uppers Make Completing a Build Easier

One other selling point of building with a short barrel upper is that assembled uppers and build kits are available, making the entire process easier and potentially more affordable.

What Size Is Best in a Short Barrel Upper?

                   short buffer systems

There are all sorts of sizes in short barrel uppers, including 5” uppers, 7” uppers, 7.5” uppers, and even 10.5” uppers. But what’s the best size?

That really depends on what your end game is. Shorter uppers handle better and are lighter than longer barrels, but short length comes at the expense of muzzle velocity and power.

A 7.5” upper is a solid middle ground.

7.5” Uppers: The Auspicious Middle Ground

While 7.5” uppers are not quite as compact as 7” uppers and certainly a bit bigger than 7” uppers, they’re still fairly light and compact.

They handle significantly better than 10.5” uppers and are a lot lighter as well. The only real drawback is that they will produce lower muzzle velocities and run a little dirtier than larger uppers - but they won’t exhibit muzzle pop as bad as with a 5” upper, so there’s that.

Basically, it’s about tradeoffs, but a 7.5” upper offers a good middle ground either way.

Shop Short Barrel Uppers and Kits Here

Gearing up to make your next build? Get your upper receiver and parts such as gas blocks and muzzle devices here at MCS Gearup. Once the build is complete you can stop back for sights, rails and handguards, optics, and other shooting accessories like lasers, slings, and anything else you need to completely customize your home build.

Consult our catalog and get in touch with us at if you have any questions.