Building an AR-15 rifle with a complete, assembled upper? Then you have one plug-and-play half of the rifle ready to go.
It’s convenient, saves time, and is easy to mate to an assembled lower. The tradeoff is that it’ll already come with everything you need so making customizations will require you to swap stuff out.
That being the case, here are several AR-15 parts that you should replace - probably.
The Muzzle Device
Chances are your AR-15’s assembled upper came with a muzzle device pre-installed on the barrel, and chances are even higher that it’s a flash protector.
Flash protectors don’t do much of anything. They obscure the muzzle flash and keep the sight picture just a little bit clearer - but beyond that, not too much.
Replace it with a muzzle brake to cut felt recoil, or better yet, replace it with a suppressor that will not only cut recoil but which will reduce noise, too.
If you are building a micro ARP, scrap the flash hider and replace it with a thread protector.
The Handguard
Today many, perhaps even most, assembled uppers come with Picatinny rails, often in a quad rail configuration.
Picatinny rails are alright, but they’re heavy and not comfortable to grip with bare hands. There are better, lighter alternatives, like KeyMod and M-LOK rail systems.
There are more shooting attachments for Pic rails, but it’s close, and more and more shooting attachments for KeyMod and M-LOK rail systems are being released by the year.
If you build with an upper that comes with a tropical handguard, forget that nonsense and replace it with literally anything else. Any other rail system is better than a tropical handguard.
The Trigger
Mil-spec AR-15 triggers are alright but a little gritty. They get the job done but for precision shooting, well, they’re not good.
There are lots of good aftermarket AR triggers out there, including Geissele triggers, drop-in Timney triggers, and even Triggertech triggers, which are the only triggers on the market that operate without the use of sliding friction.
The Stock
This is not a “must-replace” item, but if your AR has a fixed stock, you might want to look into a folding or collapsible stock, such as a telescoping model.
Both folding and collapsible AR-15 stocks can be used to make the overall footprint of the platform more compact, and collapsible stocks are more adjustable to the shooter, too.
Grips
Like the stock, this is not an AR-15 part that you should feel you absolutely have to replace, but there’s nothing special about an A2 pistol grip. There are tons of better, more ergonomic options in pistol grips, including overmolded AR-15 grips that are much more comfortable and which offer better handling and control.
The Buffer Weight
If your AR-15 is chambered in 5.56 or .223, then standard buffer weights will probably perform just fine. However, if you shoot heavier rounds like .300 Blackout or 7.62 Soviet, then heavier buffer weights will result in smoother cycling and better overall performance.
On top of that, heavier buffer weights can improve extraction and minimize felt recoil as well.
The Bolt Carrier Group
Mil-spec AR bolt carrier groups, which are phosphate-coated, will get the job done, but there are better options.
Many modern BCGs are finished with advanced coatings, like DLC, nickel boron, black nitride, and attractive, gold-tone titanium nitride. All of these are very hard, very corrosion resistant, and offer superior permanent dry lubricity.
This makes them easier to clean and requires the use of less liquid lubricant to keep them running smoothly.
Backup Iron Sights
This is not a part to replace so much as it is a part to add. Get some flip-up, offset backup iron sights that you can use if your main optic ever goes down for any reason. Remember: two is one and one is none.
The Barrel (with a Caveat)
There are lots of ways to customize AR-15 barrels, but one of the most important has to do with rate of twist. As a general rule, faster bullets need a slower rate of twist and slower, heavier bullets need a faster rate of twist.
If your AR is chambered in 5.56 or .223, rates of twist between 1:10 and 1:6 will perform well for most loads. If it’s a heavier, slower round, you might need a more aggressive rate of twist, and the opposite is true for lighter, faster rounds.
Shop Assembled Uppers and AR-15 Parts Here
Here for an assembled upper or are you just looking to replace some AR-15 parts to improve performance, handling or just personalize the gun?
Take a look through what we offer here at MCS Gearup; we carry many of the parts mentioned here among others. Shop our collection and get in touch with us at Sales@MCSGearup.com.