Custom AR Carbine Build

Currently researching, seeking information, deciding on how to go about building a potential AR15 carbine platform, I am a rookie. I am wanting to purchase a complete upper & a complete lower and put them together. I’m wanting a 5.56 carbine for home defense.

Any specific tools I need? Any specific, must know info I should know? What should I be careful of when putting an AR together? Is it safer to buy all parts from one company…or is it okay to buy a firearm from one manufacturer, and replace certain parts with another manufacturer’s parts?
I’ve been trying to do math, to budget money/time while also considering quality. I’ve had the idea of buying a complete AR, replacing the longer barrel for a shorter one, and replacing the stock with a pistol brace…keeping in mind that I want this for tight quarters.

Any info will help. I’m also curious on seeing other peoples builds, and why they favor their builds.
Thank you for your time.

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If you’re going for a barrel shorter than 16" you need to either buy a pre-manufactured complete pistol unit or a stripped lower and have it registered as a pistol when you fill out the 4473. Converting a rifle to a SBR costs you the $200 tax stamp & 9-14 month wait for the ATF to process your form before you can start your build.
If you’re not getting the upper as a set you’ll need the headspace gauges for your desired caliber. So add another $100(ish) to your cost.


You can purchase a 7-10” complete upper from companies online(PSA, BCA, etc) and then either buy a complete lower or stripped lower and install the lower parts kit(AR15 discounts). But with a barrel under 16” you’ll need a brace unless you plan on registering it as a SBR which is time consuming and more expensive. Check your state laws regarding what you can legally own first.


So as not to confuse you. If you buy a pistol buy a pistol. If you buy a carbine buy a carbine. THEY ARE NOT INTERCHANGEABLE and you CANNOT SWAP PARTS. That’s a bit over the top and not exactly correct but until you understand the differences between the two don’t get any smart ideas.

I have never purchased an assembled AR platform but I am me and you can look me up and find out who I am and what I do on this site. I’ve been driving AR’s for business and pleasure for 30+ years and I still don’t like them unless they have a piston.

There are multiple threads here about the small vagaries that will land you in jail if you cross the wrong line with a pistol platform I’m sure @Dawn has them on speed dial. Carbines are pretty safe. Do you need special tools? No a couple of riggers belts a friend with strong hands and a monkey wrench will get you done and a can of Krylon will cover the scratches.

AR’s are like Lego’s if you can follow instructions you can build one. Tools are handy but not required. If you buy a kit gun get the whole kit and pay to have the upper assembled then buy a stripped lower, assemble it put in both pins and have a ball. It’s not much harder than that.




SBRs and Pistols have their own rules to go by.

I highly suggest buying a stripped lower and tell them it’s for a pistol, purchase a pistol lower build kit and order a complete upper.

There are dozens of quality videos of putting a stripped lower together to walk you through it.

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Bite the bullet and buy the armorers wrench.


Worth every penny! The only other thing you’ll need are the headspace gauges & a bench vise.


I am a noob as well. I have done some math and at the risk of offending some on here…check out Palmetto State Armory. I personally am leaning towards a rifle but have seen crazy prices on “blemished” pistol uppers and lowers. If you get complete upper and lower, I am being told just 2 pins to put together.

I started researching a while back but because of ammo scarcity I never shot the AR platform until recently.

I was able to shoot 2 different 22 lr ARs. One had MAGPUL flip up sites and the other had standard hand guard with tall front post.

I at least know enough now to not want standard sites.

I will say I feel like I have caught an AR bug and the only way to cure it is to get one.

Good luck on your journey.