SilencerCo SCO-15 Lower Receiver Review: Top-Tier Quality

It can be easy to overlook the importance of a good lower on your AR platform rifle. After all, the bolt carrier group is usually considered the heart of the AR. And components like the barrel and trigger seem to rank higher than receivers. However, your receiver matters, and the lower receiver of your gun can make or break the build depending on how well (or poorly) it’s made. One lower receiver worth considering is the SCO-15 made by SilencerCo. Why? Well, we put the lower to the test on a 6mm ARC build, and it performed admirably. Let’s discuss.

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The SilencerCo SCO-15 Lower Receiver is compatible with AR-15 parts. (Photo: Kat Stevens)

What’s the SilencerCo SCO-15 Lower Receiver?

SilencerCo decided to start manufacturing AR components in 2020, at the height of the COVID-19 pandemic. Since then, the company has continued to develop new products for the AR-15 platform.

As a suppressor company known for manufacturing quality products, it makes sense that SilencerCo wanted to ensure that its AR parts met its high standards. The SCO-15 is designed to raise the bar of quality and performance for the AR-15 platform. It’s stripped, meaning you need to install all the necessary small parts, pins, and springs to make it work.

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The SilencerCo SCO-15 Lower Receiver is made from billet 7075-T6 and is hard coat anodized. (Photo: SilencerCo)

SCO-15 Lower Receiver Construction

The SCO-15 is made from billet 7075-T6 aluminum. What does that mean? The 7075 designation means it’s an aluminum-zinc alloy that’s precipitation-hardened. Additionally, the T6 refers to the high temperature and aging process. If you’re curious about different types, T4 is aged naturally, whereas T6 is aged artificially for the greatest strength possible. The billet manufacturing process is different from forging (most non-billet lowers are forged). A billet lower like this is heavier than the forged equivalent and is precision machined for improved dimensional accuracy.

sco-15 lower
This is a billet lower that’s been precision machined. (Photo: Kat Stevens)

What are the specifications of the SCO-15 Lower Receiver?

There are some features and specifications of the SCO-15 that are worth getting into before covering its performance during live fire. SilencerCo clearly put thought into the lower’s design and AR builders seem to be evenly divided on their opinions of said features. The SCO-15, for example, has a proprietary ambidextrous bolt catch. In reality, having an “ambi” bolt catch is a fantastic feature, but there are features not everyone likes on every gun and receiver out there.

The SCO-15 has an enlarged trigger guard that’s squared off at the rear. This blends with the aesthetic design the lower’s been given. Integrated QD sling attachment points simplify adding a sling and a flared magwell, facilitating smoother and faster magazine changes. It also has a rear tensioner bolt hole and a 45 to 90-degree fire selector window for short-throw levers. The SCO-15 is machined in-house by SilencerCo, which gives them greater quality control, which isn’t something a lot of manufacturers can claim about their lowers. This lower has a black finish and is hard coat anodized for resistance to use-related wear.

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The lower has a flared magwell for easier magazine changes. (Photo: Kat Stevens)

How easy is the SCO-15 Lower Receiver to build?

For this review, I used a Wilson Combat lower parts kit with the SCO-15. There have certainly been countless AR builds I’ve done where I used whatever spare parts I had on hand, but this time, I wanted to use a single kit for most parts. Assembly went as expected, meaning if you’re an experienced builder, there aren’t really any surprises, and if you’re new to it, you’ll just need to follow a guide for the process.

SilencerCo understandably recommends pairing their lower with their matching upper, but you don’t have to do that. I used an Aero upper and the fitment is fantastic. There’s no shifting or jiggling of any kind and no visible light between the pieces. They also make a charging handle and BCG that are optimized for use with suppressors. For this build, I did use the SilencerCo charging handle, but the BCG is the Velocity Recoil-Less model.

There are no sharp edges or uneven spots on the SCO-15. It’s well-machined and made with attention to detail. Sometimes you’ll get a lower from manufacturers with minor or even major issues that you only discover during the build process, this isn’t one of them.

Using a magwell block and vise makes assembling a lower like this easier, but it’s possible to do it without one. Once the lower is complete, mounting the upper only takes seconds.

How does the SilencerCo SCO-15 work?

Overall, the SCO-15 performs as you’d expect from a top-tier lower. It is a little heavier than some lowers, so there is added bulk, but it isn’t so extreme that it’s a real issue. The lower’s smoothness is comfortable in your hands. Thanks to the trigger guard being oversized, it’s easy to run even if you’re wearing gloves.

This is a durable lower, and while you might hate to use and abuse a gun with more expensive parts, that’s what it’s for. The SCO-15 can handle hard use, and that’s exactly what you should demand of your lower. Yes, you might be sad when it eventually gets scuffed up, but signs of use should be seen as a badge of honor rather than an ugly mistake.

The SCO-15 is a high-quality lower that checks all the boxes for what a lower should do and then some. If you’re interested in doing a higher-end build or simply want a truly rugged lower, it’s well worth taking a look. The reality is that the parts you use matter, large and small. If the lower isn’t built to specific tolerances and shifts or wiggles against the upper, you’re going to have issues with your rifle. The same goes for poor internal machining that leads to rough edges or bad angles that make it difficult for the various internals to function properly. There’s no denying the SCO-15 is well-made, and it is worth the investment, both money-wise and for the time it takes to assemble it.

Kat Ainsworth Stevens is a long-time outdoor writer, official OGC (Original Gun Cognoscenti), and author of Handgun Hunting: a Comprehensive Guide to Choosing and Using the Right Firearms for Big and Small Game. Der Teufel Katze has written for a number of industry publications (print and online) and edited some of the others, so chances are you've seen or read her work before, somewhere. A woman of eclectic background and habits, Kat has been carrying concealed for over two decades, used to be a farrier, and worked for a long time in emergency veterinary medicine. She prefers big bores, enjoys K9 Search & Rescue, and has a Master's Degree in Pitiless Snarkastic Delivery.

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