What do I need?

I’m finally at the point where I can say I’m ready to start collecting parts to build an AR Pistol. Does anyone have or know where I can find a list of every single part that I would need to build one from the ground up? I want to make a check list so that I don’t miss anything, not even a cotter pin.



You could check Primary Arms, they have lower build kits and things like that.

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I used a cleaning mat with the exploded view. It really isn’t that complicated just gotta filter thru are you paying for quality or a name.

Good luck. It’s a lot of fun


@Spence - Are you starting from blank receivers, or are you going to purchase a barreled upper?

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My plan was to purchase every little part separately as I can afford them to build one. So blank receivers was my goal.

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You’d probably be money ahead starting with an 80% lower Having all the drill points already laid out along with the milling complete will make it far easier on you in the long run.

There are also several very good “drop in trigger units” that are well worth the money and give you a much better than factory trigger when you’re done.

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Looking for the same advice as @Spence :grin: …adding on to your thread. I think the gun mat is a great idea!

@Craig6 might have some opinions? :smiley:

I’ll add to my request that I want everything as light as possible in the left hand… trying to move the weight mostly to the right hand and move the balance point back towards the stock.

If anyone has recommended lower groups, light-weight durable barrel, prefered triggers, or preferred stock, that’s what I’m looking to know too.

I have geissele triggers in mine. As @WildRose mentioned. These are drop in trigger systems. they usually have pretty good sales. I reccomend either the GS2 is SSA model. They have descriptions on their website.

The stock is a magpul MOE SL. I prefer the wider cheek weld. In my opinion magpul is the glock of AR furniture. It just always works


@Spence & @Zee Knowing what I know now and having learned a bit more about the laws concerning AR pistols I am not too far off where I started. Actually the things I would change didn’t exist when I built mine so, there you have it.

Let me get this out of the way. If you want to go down the road of building an 80% lower then Rock On! That said, having tried that option I am not overly satisfied with the final outcome of mine as I do not have mill access. Does it work? Yes. Is it pretty? No. If you want to do one as a Zen exercise in drilling and filing you will either find inner tranquility endlessly filing in places files don’t go or you will have large clumps of hair on your work bench.

Pieces, Parts and Upgrades:

IMHO the best out of the box lower on the market is the Aero Precision M4E1 lower. It as an integrated trigger guard and some very thoughtful ergonomic relief cuts. On the technical side it has one feature that is worth the extra cost all by itself, a threaded bolt release pin. I have see more lowers screwed up because of this pin and the trigger guard pin than ANY other spot. Oh and it’s flared mag well can be hit from across the room.

While I applaud you endeavor to buy each piece and lovingly inspect and fondle it, it’s a waste of time effort and a whole LOT of money. To that end I advocate buying a KIT and putting the parts you replace in a “spares” box should you need to change something later. My #1 go to place is OUTDOORSPORTSUSA.COM carbine kits can be had for $280 and up and pistol kits can be had for $300 and up. And for $50 with the kit you can buy an 80% lower just “to have”. Disclaimer: I have no interest financial or other wise with that web site/company other than I like their stuff. EXCEPT: I hate the screws that come with the hand guards as they are SOFT. I’m working on finding some Grade 5 metric button head screws to replace them.

Arm Braces: When I built mine the KAC Shockwave Blade was the best bit of kit out there. They now have a Shockwave Blade 2.0 which is ADJUSTABLE. There is a legal aspect here so you must be careful. If the LOP (Length of Pull- The distance between the forward most part of the trigger and the end of the blade is MORE than 13.5" you have entered into the SBR/NFA world.) The Blade 2.0 has a buffer tube that is milled to NOT allow you to exceed that even tho you could just put a standard military buffer tube on and make it work but it will net you a 14"+ LOP if you pull it all the way out and by proxy and SBR/NFA weapon.

Drop in triggers: Nice bits of kit if you want to spend the money or if your trigger bits from the bag of parts really suck. Most triggers are acceptable at a minimum and some are quite good. I would suggest you try the parts kit trigger before ordering a drop in.

Fore Arms: The ones that come with the kits mentioned above are light, slim and very comfortable. They are either in Key-Lock or M-Lock configuration so all those options are available. I don’t do rail and such so that part matters little to me. Again, I hate the screws that attach them to the barrel nut.

When I built my pistol I was $345 into it as I added a 10" fore arm and a Krinkov flash can (which fits inside the fore arm) and I bought a $56 Palmetto State standard lower at a local shop. So mine cost $401 and I must say it is a sweet little noise maker.

Hope that helps, be glad to answer questions and such if desired.




That’s a lot to read and very good info to boot.

When it comes to the rear end I’m pretty sure I have to go with a “brace” instead of a stock. I was thinking about a folding brace.

I’m not sure about other states but the only real differences between an AR Pistol and a SBR in Michigan is the SBR can have a vertical foregrip and an actual stock (aside from the tax stamp as well.)

Funnily enough in Michigan you can’t have a loaded long rifle or “long” shotgun in your vehicle, however with a CPL you can have a loaded AR Pistol or SBR in your vehicle. Go figure…

What is a good barrel length? Also should I be looking at 5.56/.223 and have a coop with my existing AR, or should I consider 7.62/.308? I don’t have anything in those last calibers currently. (I briefly considered 50 Beowulf or 458 SOCOM, I would like >some< capacity though lol)


@Spence - As has already been mentioned, look at Aero Precision M4E1 lower receivers. I have one that I plan to build up myself. Aero also sells upper receivers and parts kits for the lowers. Mission First Tactical and Magpul both make good “furniture” such as butt stocks and pistol grips. Look for M-Lock compatible forends that also free float the barrel. Avoid “delta rings” as they are not ideal for the best inherent accuracy of the barrel. I know that you want to build a pistol, so you will be stuck with a pistol-length gas system. If you were building a carbine, I would strongly suggest using a mid-length gas system. Good luck with your build!


@James has built at least one - I’ll nudge him to add his suggestions.


@Craig6, try McMaster-Carr for the button head screws. Their online catalog is fairly easy to navigate and their customer service line is manned 24 hrs a day. Good selection there.


@Spence I would invite you to do some research on AR pistols. They are regulated by the FEDERAL gov’t, your state has little to do with it.

Yes, you must have a ATFE approved BRACE otherwise it is not a pistol even though you CAN shoulder it.

A folding stock is a neat bit of kit but pretty impractical if you think about it (you can’t fire it folded) unless you go gas piston and that is a different animal $$$$.

Barrel length is anything you like from 16" in. I have a 7.5 and it is accurate to about 150 yds but will get your attention out to 300. It’s more about weight and balance with an AR pistol.

Ummmmm on .308 my ears will beg you not to do that. The 5.56 and 223 Wylde is loud enough and the muzzle flash is stupid big enough to light up the room and blind you at the same time,

I doubt you could find one but do not get a 223 Rem barrel as it is not preferred to shoot Mil-Surp or all 5.56 ammo.

@David38 Thanks for the info. I haven’t put a lot of effort into the search as it is together but I am familiar with McMaster as I work in the trades. Good info.



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Top is an Aero M4E1 best bang for the buck great fit and finish and a bonus of an integrated trigger guard, flared magwell, threaded bolt pin, tension screw under the rear push pin to take any wobble out of a loose fitting upper, no problems with any type of mags dropping free. the Magpul MOE works but it’s sloppy and loose on the buttstock, the grip works fine very basic has more of an AK grip angle and feel.

Middle is an Anderson AM15, people will dog you about it, I got it for dirt cheap during a grand opening sale around $39 or so. It works nothing fancy, open trigger area, roll pin for the bolt catch lever needs to be tapped in with a punch, and everything aligns, some Magpul mags didn’t drop free when new, took some breaking in, other mags dropped free. The Daniel Defense furniture is my favorite it’s rubberized and overmolded, the buttstock is snug, no wiggle, and the grip is spot on without a beaver tail so you can get in good and tight and the web of your hand fits perfectly inline with a more vertical 1911 like grip angle.

The bottom is a Juggernaut Tactical, it’s a billet lower vs the other two which are forged. Nice sharp angles, laser etched graphics, integrated trigger guard, adjustable tension screw to tighten a loose upper, an ambidextrous bolt catch release, angled/cut magwell swaps and drops all mags and a threaded bolt pin. Mission First Tactical minimalist stock real deal made in USA fits nice and snug, Magpul K2 pistol grip has an improved texture, grip mold/angle and a beaver tail.

My son runs an Aero Gen 2 which is very much like a milspec open trigger lower with a tap in roll pin I believe but does have a tension screw.

Of these I really like the Aero M4E1 it is truly a great value as it has billet style fit and finish even though it’s forged and the threaded bolt pin is really nice. I can basically buy about 2 or 3 depending if I find a sale on these for the price of 1 or 2 Juggernauts.

That’s my take on lowers and furniture, the Geissele drop ins are nice, as far as the stocks that’s a reference for rifles. I think that braces would work best for a pistol vs a blade, tube only, or a PDW retractable.


One product I found that has a decent trigger and will give you all the springs, detents, and reall anything you need to make a functional lower is the Bravo Company USA’s Lower Parts Kit. The trigger is a polished milspec so there is still a heavier trigger pull, but their triggers are heat treated correctly and the parts have a snug fit.

I’ve also used Ballistic Advantage for uppers before. They are the company that produces all the barrels for Aero Precision. They have great entry level barrels.

As far as a lower, a lot of people use cheaper lowers, and that’s fine, but be advised you may have to do a little finish work with an Anderson or Palmetto State Armory upper. I prefer to use Sons Of Liberty Gun Works. I like that they are forged and that they have a high reputation for impeccable QC. If I had more cash to spend I would just buy their uppers as well.


Thanks guys!

So where I work was hosting a gun show this weekend, one of the vendors was new and trying to draw folks in. Due to it being the last day of the show he was selling his AR parts at a 15% discount, he recognized me as working security for the building and gave me another 15% discount. So I bought an Anderson Arms AM-15 lower receiver. Now the fun begins as I start collecting parts!


@Spence That’s awesome! So you got a lower for like $30!!

Here is what I built for the princely sum of $401. The EO Tech and AFG I had laying around and the iron sights were freebies with the kit purchase. In this photo the blade is all the way in but I have since moved it out to 13.4" LOP. (Edit to add: the pistol grip is a Magpul K2+ grip and it features a more vertical profile which is much more comfortable (to me) than the standard)

It’s a little nose heavy due to the Krinkov can but it swings and points well and balances just forward of the upper receiver with a full mag. I am considering swapping the EO Tech for a Vortex etched reticle 0x Spitfire just so I don’t have to deal with the batteries.





Anyone have any input on this? A little pricey but for now I can start saving

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Looks nice but it will be LOUD and BRIGHT. As you noted a bit spendy for just an upper. You will still need a BCG, Charging Handle, Some form of Brace, Buffer, Buffer tube, Buffer Tube Spring and a LPK to finish off the lower. IMHO there are better options out there for that price.