AR 15 Parts: Frequently Asked Questions
GW. Ayers, Rainier Arms Firearms Academy
Q: Can I still buy AR15 parts?
A: Of course you can! As a matter of fact, it's pretty easy and availability if very good, particularly in the mid- to top-tier range. You must buy the receiver from an FFL (Federal Firearms License holder)and have the state and federal paperwork satisfied. If you are seeking a complete AR-type weapon, you must also see an FFL holder to get the red tape handled. This is a painless process.
Q: Are AR-15 parts universal?
A: The AR parts world is standardized, but we must be realistic. Parts are made my machines, and those machines are run by humans. When humans are involved, there will always be a few parts that fit the agreed-upon standard. We have all seen that claim, better than mil-spec. In most cases that's a good thing, but in a few circumstances might hinder function and/or assembly. The main remaining few differences I've seen mostly surround buffer tubes. Mil-spec tubes have largely taken over that world but there are still some civilian pattern ones in the market.
Q: Can you mix and match AR15 parts?
A: Yes. In fact, I think mix and match is the best part of having this system. The largest problem you might encounter is when trying to cross-load elements of the Direct Impingement system vs the gas piston system. DI parts are readily available, and gas piston parts as well, just sometimes not in such numbers. While the gas piston system has a lot of upsides and just a few downsides, the biggest drawback (at least in our opinion) is field repair using DI gun parts. There are tons of DI parts in the wild; much fewer Gas Piston ones to scavenge from in a pinch.
Q: What parts will fail on an AR-15?
A: It depends. The quality of the parts kits and the manner in which the rifle was assembled has a lot to do with the wear and tear on the gun. I think the biggest wear item would be the gas rings on the bolt. They must be replaced periodically. There can be fist fights over the frequency you should inspect them. I suggest you check your owner’s manual for the recommended interval. After that, it's about barrel and gas port erosion. Thankfully for most of us, this isn’t an issue. Most of us don’t shoot them enough in harsh conditions to worry about this as a near-term consideration.
Q: What is the weakest part of an AR-15?
A: Bolt and chamber for sure. But. Proper maintenance and inspection of the bolt and chamber will keep this gun in the fight. Keep them clean and properly lubricated. This rule can be applied liberally across our lives and serve us well.
Q: Is it cheaper to buy or make an AR-15?
A: There is no easy answer to this question, but generally speaking…the fully assembled AR can be less expensive. When you assemble your own you control the entire parts configuration (and allocated budget). We tend to spend a bit more on the components that are important to us, like the trigger, barrel, and bolt carrier group.
Q: Can you legally own an a full-auto AR-15?
A: We absolutely can own Full Auto weapons in this great country of ours. However, there are a ton of hoops to jump through, and it is very expensive. Access varies from state to state and for most people it is easier to rent one than go through the expense of purchase and the tax stamp process. However, if you find it is a must-have and your state allows it, the ATF site can walk you through the process. Silencershop has a ton of information that can assist you in making the decision to purchase class III weapons.