Firearm Part Kits: Can You Mix and Match?

Building your own gun from scratch is an ideal way to know the 
details of your firearm, not to mention gain a sense of accomplishment. But what if you want to use pieces from multiple firearm part kits? Can you do that?

The short answer is yes, but there are a few things to keep in mind.

Mixing Low- and High-End Parts

When dealing with the majority of gun parts, the best way to see if they’re compatible is to try them out, research them, or both. There are, however, some factors that might indicate compatibility ahead of time.

The AR platform is designed to be modular. Beware of mixing low- and high-end parts, however, because they may not play well together. Getting a mil-spec tube and a commercial-spec stock will result in problems with fit, and they may not work together at all.

If you’re nervous about mixing different specs, try starting with a complete 
lower receiver kit and only messing with the upper, or vice versa. Once you’re familiar with all the parts in the firearm kit, you can branch out into more adventurous — and fun — builds.

Consider Your Individual Preferences

If you want a particular style on the upper receiver of your 
AR-15 and a different style for the lower, using different kits can make that happen.

For example, if you want a sleek and modern barrel assembly without a forward assist from a certain brand, but the lower kit that matches doesn’t quite match what you pictured, you can use a complete lower receiver kit from another brand instead. Or, of course, build one yourself from the ground up.

If you want a unique dual-tone look, consider changing up the colors of your upper and lower receivers using different kits. What better way to stand out on the range than using two unique firearm part kits to change up your color options? We’ve seen a tuxedo jacket and jean shorts work before, and there’s nothing stopping you from making the same bold choices for your firearm.

What About Accuracy?

Fortunately, using parts from different kits won’t have much of an effect on the accuracy of your firearm. Again, ARs are designed to be modular and customizable. Most parts can swap in and out with ease and not change your accuracy.

The only wrench in this assurance is, again, combining a very high-end lower receiver with a bottom-of-the-barrel upper, or vice versa.

Use Trustworthy Sources

In addition to choosing quality firearm part kits, make sure you’re purchasing from trustworthy sources. Avoid Mr. John Smith on Craigslist who promises you’re getting a “like-new” complete lower receiver kit. You might be, but it also might be a lemon, and why take the risk with something as important as a gun you’re building from scratch?

Shop around and compare suppliers. Check reviews and what materials the kits are made out of. Look for anodized metal and high-quality, 
billet aluminum. An early investment in quality materials will help make sure your parts fit together and your firearm is exactly the way you want it.

Adjust Your Tolerance

AR 15 standing upright on tree stump

We’re not talking about your patience levels here. We’re talking about how loose or tightly the pieces of your various firearm part kits fit together.

Some people want a super solid precision fit when they first start using their gun and deal with a gradual loosening with use. Others don’t care one way or another, so the variations between manufacturers don’t matter to them.

Whether you prefer a precision fit or don’t mind a little light shining through the seam, experiment with different parts until you get the feel you want.

Watch for Proprietary Limits

While most AR parts are, in fact, interchangeable, as we’ve said, some companies have proprietary designs that won’t work with parts that aren’t theirs. For example, piston systems are almost always designed to work in a very specific way within the gun.

So in your piston-driven system where the gas key would normally be, there may be a strike face instead that may not cooperate with another company’s piston rod. Check that the parts are not proprietary or attached to other parts in ways you can’t undo.

Shop JSD Supply Firearm Part Kits

Since 2013, JSD Supply has been the trusted source for complete lower receiver kits, Glock-compatible kits, and more. We supply thousands of people each year with the parts, tools, and resources they need to build their dream firearm in the privacy of their own home. 
Contact us or utilize our live chat feature to ask questions.