Good news! You’re already on the right track. Once you’ve decided you want to build a PCC the next step is as simple as selecting your preferred pistol caliber. The most popular PCC calibers are currently .45 ACP, 10MM, or 9MM with 9MM being the most popular of the three. This is mainly due to parts availability, ammunition costs, and community preference.

Once you’ve decided which pistol caliber is right for you it's time to start digging into the caliber-specific components.

Now for the guts of your Lower Receiver. To make a functioning lower receiver you’ll need all the parts to build out the internals. Luckily, most firearms companies provide LPKs (Lower Parts Kits) these will normally include everything you’ll need such as your takedown pins, springs, hammer, trigger, detents, etc.

Although many Lower Parts Kits come with a standard A2 style grip, It's common practice to upgrade your grip for one that is most comfortable for you. As you become more familiar with your firearm, it is normal to decide to change your grip out for a different angle, grip material, shape, color, or design to best fit your preference. AR9 or AR45 specific lower receivers are designed to work with basically any AR-15 style grip. Adding a grip is one of the many great ways to personalize your firearms.

The next thing to check off the list is the task of selecting a stock or brace for your PCC.  

Which should you pick? Stock or Brace/Blade? 

For simplicity’s sake, If the PCC you plan to build has a barrel length shorter than 16 inches you have the option of many different ATF-approved AR-15 Pistol Braces and Blades. If your PCC has a barrel that is longer than 16 inches you can take your pick of the many different rifle stocks that are most comfortable for you. 

Want to learn more about pistol braces?

Now that you’ve got the LPK, Stock or Brace, and a Grip for your lower receiver, you’ll need a buffer tube kit to put between your stock or brace and your lower receiver. Your buffer tube kit consists of the buffer tube, buffer spring, a pistol carbine-specific buffer, castle nut, and end plate. A buffer system's main job is to allow the proper cycling of the Bolt Carrier Group when your PCC is fired. Be sure to pay attention to the type of stock or brace you choose and be sure that the buffer tube you select is compatible with your stock or brace. 

Congratulations! At this point, all the key components needed to assemble a complete lower receiver have been covered. The next phase is to acquire all you’ll need to build the entire upper assembly.

Bolt Carrier Groups for Pistol Calibers carbines are a large reason for what makes PCCs so interesting. Without going too deep into the weeds, PCCs operate on what is sometimes known as a blowback BCG or blowback gas system. Because of the forces being put up against a BCG, it's important to select a good quality component that can handle the abuse for as long as possible.  For any build you do, it is important to select the correct Bolt Carrier Group for the caliber you will be shooting with. 

A good quality charging handle is often overlooked when people do their builds. But having something well built helps boost the reliability of your rifle and the overall comfort and ease of operation. Ambidextrous charging handles are a good consideration for a solid upgrade.

Barrels are caliber specific so be sure to select the correct barrel chambered in whichever caliber you have chosen. 9MM or 45ACP Barrels are normally available in lengths between 4 inches up to 16 inches in length. Because of all the different options choosing a barrel length can be a tough decision. 

Typically the best place to start when selecting your barrel length is to decide what you plan to use it for. For example, someone who plans to use their PCC for different things like home defense, concealment, close quarters training/target practice, or other similar purposes might choose to go with a barrel between 4 to 14 inches. Those who prefer to have a stock, or those who are involved in certain competitive shooting sports might choose to go with a 16-inch inch barrel. 

Get a Muzzle device that is compatible with your barrel. Most AR-15 Barrels come with threads on the end to accept a muzzle device. And just like most options with PCC parts, there are multiple options and features for different AR9 muzzle devices. It is worth taking the time to go through the different options of muzzle devices, their functions, features, looks, and size when selecting an option that will work best for you.

Once you’ve selected your barrel and muzzle device, the next step is the handguard. The most widely available type of handguard currently would be the free-float style handguard. These types of handguards slide over your barrel and mount or clamp onto the barrel nut. Most firearms companies provide a barrel nut with the purchase of your handguard to be sure everything fits correctly.

Handguards come in different lengths and it's important to be aware of your barrel length with making your choice. A handguard is designed to protect the barrel from damage and also to protect your hand from the barrel. A handguard that is too long and extends past the muzzle of the barrel is not safe and should not be used. A handguard that is too short might make it difficult to hold onto the rifle or fail to protect the barrel from damage.

Don’t forget about your sights! Generally, when doing a PCC build, you’ve got three options. You can choose to mount some iron sights sets that come with a rear and front sight. You can choose to mount a red dot sight, or you can choose to mount both. Most people choose to utilize both flip-up sights and a red dot. That way, If your red dot fails, you’ll have backups to help you keep shooting straight. The world of optics and red dots is a big one. Don’t be intimidated, just like when selecting a muzzle device. Take your time to check out all the different capabilities, features, functions, and price points to help decide which is best for you.