What is an AR-15 Complete Upper?

AR15s are pretty simple, but even I was confused by the terms at first. Don’t worry, it’s not hard to figure out.

A complete upper is a fully operational upper receiver with a barrel, charging handle, gas block and tube, bolt, and handguard. It can be installed onto a complete lower and will be ready to shoot. Complete uppers may not include sights, but they have all the hardware required for operation.

What are you looking for in an upper? Looking to build an AR, or simply buy an upper for a second caliber? I have some great recommendations for you.

What Comes With a Complete Upper?

A complete upper comes with everything but sights. Depending on the gas block installed, you will need either a rear sight or an optic of some kind, but everything else should be included. Some uppers, known as barreled uppers, don’t come with a bolt carrier group or BCG. Be sure to identify which one you are looking at.

Traditional ARs have a gas block that doubles as the front sight. Those need a standard rear sight. Most people opt for a polymer flip-up type sight. There are metal ones available, but they’re generally more expensive. You can get a fixed rear sight, which is what I personally like better. They are installed with simple pliers.

With the tall, front sight/gas block, you can’t really use a scope or red dot sight. The front sight is in the way. There are risers available that will lift the optic slightly above the level of the front sight post, but at that point, it’s so high that you can’t get a solid cheek weld on the rifle. Plus, the sight post still blocks your view.

Lower profile gas blocks allow for a red dot or scope let you use a scope or red dot, or even traditional sights if you want to. I use a scope on my hunting rifle, and sights for general target shooting.

Can a Complete Upper be Shipped to My House?

Any AR upper can be shipped to your house without hassle. There are no shipping restrictions on them. An upper can be ordered online and shipped to your door through USPS or any freight delivery service. There are no federal background checks or paperwork required for an AR upper, assembled or not.

There you have it. You can send or receive an AR upper in the mail or via freight. It’s no more a hassle than sending a gift basket to grandma. I’ve recently bought four complete uppers online and had them shipped to my door.

Do all AR uppers Fit all Lowers?

Most AR uppers share the same basic design and will fit any lower of the same size such as the AR9, AR15, and AR 10. Any AR-15 upper should fit on an AR-15 lower unless specified by the manufacturer. Sometimes, receivers are out of spec and can be hard to pin together.

Which Uppers are Best?

There are no “best uppers”. Make your choice by comparing your budget and the options you like against what your needs are. Even cheap AR uppers tend to run well.

Two companies I like are Bear Creek Arsenal and Palmetto State Armoury. I own four Bear Creek Uppers and zero from Palmetto, so I guess you could say I favor them more. Why not if they’re cheaper and seem to work well?

I do really like Bear Creek Arsenal. I bought their side-charging uppers and love every one of them. They have every caliber you want. They have the best value optic-ready complete uppers on the market. I recommend the flat-top style like the ones I have. It makes mounting accessories simpler.

The flat-topo has a rail on top of the receiver, and the rail continues all the way down the handguard. That gives options for mounting optics in different positions, as well as lights, lasers, or whatever you want. Also, the slots on the sides and bottom are M-LOK slots for M-LOK accessory mounts.

Best Calibers for a Complete AR Upper

The first caliber you should have for an AR is 5.56/223. Either or, and yes, they are both compatible in the same gun and will not result in too much pressure.

After that, your next caliber can be whatever you want. However, I do have recommendations. I recommend that eventually, you have an upper (or complete rifle) in the 35-45 caliber range, a pistol caliber, and a 30 caliber. Here’s exactly what I recommend.

I’m a big fan of the 7.62x39mm cartridge. That’s the infamous AK47 ammo. With the 30 caliber bullet, it’s a great option for hunting to 250-yards. There’s plenty of cheap ammo for target shooting too. Between .223/5.56 and the 7.62×39, you have the two most common calibers in the world.

I know there’s a lot of hype around the 50 Baeuwolf and .458 SOCOM, but those aren’t so great when you look at the ballistics. For a heavy hitter, go with either the 450 Bushmaster or 350 Legend. The 450 Bushmaster is the king of big-bore AR calibers, and the 350 Legend is its smaller counterpart with 1/3rd the recoil.

I also recommend an AR-15 upper in 9mm. No, not an AR-9 upper, an AR-15 upper in 9mm with a 16-inch barrel. it also has inexpensive ammo ans will be easy to hit targets at 1000-yards with minimal recoil.

If you get uppers in those calibers, you will have the three most common and universal calibers in the world, and one real heavy hitter should you need an excess of energy and lead.