There are three types of buffer tubes for ARs and the one you pick depends on what you are building. There is the traditional long A2 fixed stock style buffer tube, the 6 position M4-style telescoping stock tube and lastly the pistol buffer tube. Since I am building a pistol, that will be our focus. The pistol buffer tube has no provision for a stock and is just a straight tube. Do not use a rifle tube on a pistol build just to be safe legally. Other than that, the installation is almost identical other than the backplate (shown below the buffer tube in the next photo) which is indexed for rifles but typically not for pistols.
Step one: Install the rear takedown pin assembly. Insert the pin from the right to left. Put a dab of Tetra Gun Grease in the detent hole and then push the pin and spring in. The grease will help retain it.
Step two: Put the backplate on the tube and thread it into the receiver almost to the end. Watch the detent spring and make sure it is compressing properly into the hole and not bending. On pistol builds I will push the plate down with one hand while threading the buffer tube on with the other. Stop in time to insert the buffer spring and detent in their hole. Push them down and thread the buffer tube on the rest of the way. Note, you can stake the tube into position or use a small dab of blue Loc-Tite to hold the buffer tube in position. Note how the front of the tube overlaps the detent pin just enough to hold it in position.
Step three: Install the Arm Brace. The SB Brace I got from Palmetto has a hollow rubber cylindrical hole for the buffer tube to go down. Of course that thing will not want to slide down the tube by itself. I lightly lubricate the buffer tube with silicone spray and then slide/hit the brace into place. Only turn the brace clockwise as you install it lest you unscrew the buffer tube. I did use a rubber mallet to help get it down the tube faster.
So with that the brace is installed. My next post will be about attaching the upper and finishing the assembly.
Sources For AR Parts
The following are all vendors of AR parts including barrels, handguards, triggers, magaziness and what have you that I use and recommend:
Beware no-name knock off websites selling generic import stuff. Some of the parts are counterfeit and not rated for firearms use.
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In this step we will install the selector spring and detent along with the pistol grip. As you can imagine, I am a grip snob. I do not like the Mil-Spec grip much at all but do like the MagPul MOE and MIAD grip. For me, the lower-cost MOE grip is just fine – it feels good in my hand and is durable. It’s pretty much all I use on ARs other than target rifles where I prefer the Ergo grip with a palm shelf.
So, first off, I need to point out that in this step we install the spring and detent pin for the selector lever. Both the spring and pin are unique. In the next photo, the selector spring and detent are on the left. On the right is a detent pin and spring for the pivot and takedown pins. Be sure to use the heavier detent and spring on the left for the selector. Also, consider getting spares from Brownells because they are really easy to lose.
Step one: Turn the receiver upside down, put a dab of Tetra Gun grease (or whatever brand grease you like) in the receiver’s detent hole and then insert the detent pin point first. The grease helps hold the pin in as you move things around plus lubricates it:
Step two: I like to put a dab of grease in the spring hole in the pistol grip to keep the spring from falling out. This helps reduce my lost springs. It’s way too easy for your mind to wander and have the spring fall out.
To install the grip, I lay the receiver on its side and push the grip into place. This grip was so tight that I had to tap it into place with a rubber mallet. Go slow and make sure that the detent spring lines up properly with the pin. If you go nuts pushing/hitting it together you can kink the spring and ruin it.
The Magpul grips come with a screw that can be installed via a slotted screwdriver or a hex key, which I prefer. Also note the yellow stuff on the screw – this is a pre-applied threadlocker so you do not need to add more. If you are installing a screw that does not have a lock washer or any threadlocker on it, you may want to apply a bit of medium strength Loc-Tite. Now, to get that screw down there, I angle everything back and slide the screw down the back of the grip just like a ramp and then I use my Allen wrench to tighten things down. Because I can’t get a good grip on the wrench due to my carpal tunnel, I use an adjustable wrench to give me just a bit more torque. Many of you may not need to do that. You are looking for firm – not Big Mongo torqued down tight. There are torque specs for everything but I do farmer ballpark tight on non-critical stuff.
Once the screw is installed, the bottom end cap is snapped on place and you are done. Note, this cover can also be replaced with toolkits that slide up in the grip if you so desire. I’ve not done it yet but am considering it.
The next step will be to install the buffer tube.
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The selector assembly is what allows a regular AR to either be on “Safe” by blocking the trigger’s movement or “Fire” my allowing the trigger to pass. It’s actually a very straight forward design and I like those. Now I like ambidextrous selectors and they are just like a normal one but have a small lever that is screwed on to the operating side after the selector is installed. This is a Palmetto State Armory (PSA) model that works just fine for me. Note, some guys like these and some don’t because you will feel it on the other side, which some guys find to be weird and not to their taste. Bottom line, use what you like. If you’ve never felt one before, try and hold an AR with and ambidextrous selector before you buy one.
To install it, first cock the hammer and insert it from left to right with the selector pointing in the “Fire” direction. You may need to wiggle the trigger some to let the selector pass. If you are using a Mil-Spec selector, you are done other than function testing. If you have an ambidextrous selector, most have a groove on the other side and you simply mate up the right side lever. Before install the small screw that holds in it place, put a bit of blue medium-strength Loc-tite on the screw so it is held in place. If you do not apply some form of thread locker, the screw will loosen and fall out.
To function test the fire control group (FCG) overall, you need to do the following but remember to NOT let the steel hammer slam into the aluminum magazine well – control the hammer’s movement with your thumb, fingers or whatever (meaning hold it – don’t put your fingers in front of the hammer and hit them – that hurts!!). Each test below assumes that you can accomplish the step – if not, something is wrong:
Cock the hammer back and the trigger should grab it.
With the selector on FIRE, pull the trigger while holding the hammer with your thumb to control its movement – the trigger should release the hammer.
With the selector on SAFE, pull the trigger and the trigger should not be able to move. If the hammer is released then something is very wrong.
Now, put the selector to FIRE, pull the trigger back and while holding the trigger back, cock the hammer – the disconnector should grab the hammer and when you release the trigger, the hammer should move from the disconnector to the trigger body. Now, pull the trigger and it should fire like normal.
Now, a word of caution – if you do not feel comfortable with any of this, please see a gunsmith. If you have any doubts at all, please see a gunsmith. I want you to enjoy assembling your AR but I want you to be safe even more.
That’s it for this step. Next up is installing the pistol grip, which also includes installing the detent and spring that hold the selector in place because the pistol grip holds them in position.
If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@ro*********.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.
AR Parts Sources
There are a lot of reputable AR parts vendors online but beware of eBay and bargain basement dealers that sell airsoft parts and tell you they will stand up to firearm use – they will not. At any rate, here are my top sources of AR parts:
The hammer assembly includes the pin, spring and hammer itself. In the next photo, the hammer group is to the right. This is an enhanced trigger group from Palmetto State Armory (PSA) that I really like and recommend for people wanting a decent low-cost trigger for a basic build.
It’s straight forward to install with one important detail to get right – put the spring on so the loop is to the back and top of the hammer and the legs wind down clockwise off the hammer. Installing the spring the wrong way can have weird not always predictable results. I’ve had rifles that fired fine and others that doubled. Be sure to install the spring the correct way:
Now this next photo is of a fire control group installed in my Strike Industries jig that is great for tuning. It’s not the PSA enhanced trigger but I wanted you to see the way the hammer spring’s legs must sit in the trigger pin’s groove. This is very important as it locks the pin in place. You may need a pair of needlenose pliers to adjust the leg to make sure it does rest in that groove. By the way, the part the strikes the firing pin is the straight flat face so when you install the hammer, the face is forward as you see in the next photo.
To help line things up, I either use a punch or a little slave in. The hammer spring is pretty strong and something to help you line it up while you install the cross pin will seriously lower your stress level. Here, I am using my slave pin and you can see the actual hammer pin coming in from the left. As a reminder, the trigger and hammer use the same pins.
Next, you need to function test the fire control group. DO NOT LET THE HAMMER COME FORWARD AND SLAM THE MAG WELL!! You need to use your thumb or something to ease the trigger up. A steel hammer hitting an aluminum receiver’s magazine well is not a good combination. Pull the hammer back and the trigger should catch it. Next, pull the trigger while holding the hammer and the trigger should release the hammer letting it come forward.
Done! On to the selector assembly.
If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@ro*********.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.
AR Parts Sources
There are a lot of reputable AR parts vendors online but beware of eBay and bargain basement dealers that sell airsoft parts and tell you they will stand up to firearm use – they will not. At any rate, here are my top sources of AR parts:
An AR trigger assembly is four parts not including the pin that holds the assembly in the receiver. I like Palmetto State Armory’s Enhanced Trigger Group that has a polished nickel boron finish for my basic AR builds. My favorite trigger manufacturer is Geissele and have used a number of their models over the years but they are pricey. The PSA enhanced trigger is $39.99 and a nice improvement over the normal Mil-Spec trigger. I should note that even the regular trigger from PSA is not bad. I have used build kits from others, such as Anderson, where the trigger felt very “gritty” until it wore in whereas the PSA triggers have not had that feeling out of the bag.
So, when you get a trigger group from PSA, as well as most other vendors, they will have the components in a bag. Pour out the contents and organize them to make sure all the parts are there. Notice I am using a green fabric work mat. These are made by several companies and the benefit is that the fine nap of the mat softens the impact of small parts so they don’t fly/roll all over the place. It helps keep stuff from getting scratched up.
In the next photo you will see the trigger and hammer assemblies and all the parts that should be there. On the left is the trigger assembly – disconnector, trigger pin, small green disconnector spring (note that the vendors do not always color this spring but it is uniquely shaped), the trigger itself and the trigger spring. On the right is the hammer assembly and starting at the top you have the hammer pin (the pins are identical by the way), the hammer itself and the hammer spring.
Even though this trigger is polished, I polish the mating surfaces to a mirror finish with a Dremel, felt wheel and a fine polish such as Flitz. I also remove any burs/rough endges that I encounter with a fine stone. I don’t change the geometries – my goal is just to get things nice and smooth. Note, if you skip this the trigger will need to wear in to smooth out.
Next, install the trigger spring. Note the orientation of the front of the spring under the nose of the trigger:
Now if you look at the disconnector spring and you will notice that one end is wider. You push that wider part down into the round pocket that is machined in the back of the trigger.
See how the bottom is wider? This particular spring is colored green. Rarely are the colored – you need to go by the shape.
Now you have an option that will make your life way easier – assemble the trigger group outside of the receiver using a slave pin. I’m just going to talk about modern ARs and not all the ban-era Colt hijinks or oversize pins for worn rifles. In general, the trigger and hammer pins have a diameter of 0.154″. This is the same size as a #23 drill bit. You can go, buy a cheap bit, cut the shaft off so the length of the pin is the same as the width of the trigger. I would recommend using sandpaper to round the edges of the pin so you wind up with the following:
The silver pin above is a slave pin. The purpose of the slave pin is to hold the trigger assembly together. When the actual fire control pin is inserted, the slave pin is pushed out the other side of the receiver and its job is done. We do make and sell slave pins – click here to open our store in another tab.
You can function test the disconnector and make sure that it smoothly rocks back and forth with the spring supporting it.
Now, if you do not want to go the pin route, you will need to juggle everything in the receiver but I would still recommend using a 9/64″ or 1/8″ pin punch to help line things up from the right side as you are looking down at the receiver. They are smaller than the normal pin so just expect to do a bit more positioning. This method works fine – it’s just not my personal preferred method any longer.
Ok, so let’s say you did take my advice – now place the trigger assembly down in the receiver with the trigger facing forward. Put some pressure on the top of the trigger assembly with your thumb, line up the slave pin with the hole and push in the real trigger pin from the left to the right. Note how I have the groove on the left side – one of the hammer spring’s legs will lay in that groove and lock the pin place. Now it just becomes a matter of wiggling thins around and pushing the pin all the way through. Be sure to catch your slave pin before it falls out. This does not take a ton of force. If the pin isn’t going in all the way and things are lined up properly, use a rubber or plastic faced mallet to tap it in.
Note how the slave pin is exiting the receiver as the actual trigger pin is inserted.
Once installed, squeeze the trigger and make sure to is going back and forth with the spring. Double-check also that the disconnector rotates also. In both cases you should feel the springs doing their job.
If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@ro*********.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.
AR Parts Sources
There are a lot of reputable AR parts vendors online but beware of eBay and bargain basement dealers that sell airsoft parts and tell you they will stand up to firearm use – they will not. At any rate, here are my top sources of AR parts:
In this step, I’ll install the bolt catch. This is the part that catches the bolt when the magazine is empty or the operator wants to lock the weapon open. In terms of risk, this step has probably caused more blemished receivers than any other. What I hope to show you is a method to minimize that.
The assembly is made up of the catch itself, a cross pin that secures it in the receiver, a spring and the bolt catch buffer. In this post, I am actually installing a Strike Industries bolt catch. I like to have a slightly larger paddle to operate the catch and Strike model is a nice size. If you ever want a giant paddle, Wilson makes one but it is just too big for my taste.
Here is the catch, it’s roll pin directly underneath and then the spring and detent to the right.
Where we are working on the receiver is right here – just above the mag catch:
The spring followed by the detent go down in the hole just above the magazine catch. The bolt catch is then inserted in the slot and the pin secures it. This is when you wonder if a third arm is needed 🙂
Now, this step is really risky. One slip and you will mar your receiver so take a minute and put some duct tape on just in case. I like duct tape because it is thick and sticks really well. I’ve used other types of tape in the past and it really is just cheap insurance. If you do this and what you use is up to you. You are mainly worried about the receiver, to the right of the humps/lobes where the catch is going to be installed.
If you want to lower your risk of scratching your receiver, put a heavy tape around the assembly for protection. I’d recommend a duct tape – I’m using Gorilla Tape in this photo.
Now I use three punches for this. I bought two rubber coated mag catch punches from Wheeler. They work but I wish they were longer and you still need a third to make it easy. Let me explain a bit more. The Wheeler punches are half circle designs which gives you better clearance but I still use my long Astro Pneumatics 1/8″ punch to reach down and drive the pin the rest of the way in. Like I said though, you do need three punches for this.
The two black punches make up the Wheeler 710906 bolt catch tools and I literally use them with every build. Above them is a longer roll pin punch that I use to finish the install. I wish the Wheeler punches were about an inch longer and they would be perfect for me but note I do use them on every build.The Wheeler punches are must haves for three reasons – they are flat on one side to let you get in closer to the receiver, they are rubber coated to protect the finish and you have both the 3/32″
Ok, so first take the roll pin starter punch and install the pin on the right side part way. By getting it started you have less to try and mess with as the assembly comes together. See how the punch is right next to the receiver? You need to lightly tap this with a small hammer to drive it in while not hitting your receiver – this is why the tape is cheap insurance.
The Wheeler starter punch lets you easily begin the pin with zero drama and swearing.
I like to put a dab of grease in the hole to hold everything gently in place. This is not a normal step and just something I do. You then insert the spring first and the buffer on top. You’ll notice with the AR design that a spring always has a detent or buffer between it and a moving surface to protect the spring.
I put a dab of grease in the hole to hold the spring and detent in place.
Next, I use the roll pin punch from Wheeler to align bolt catch and hold it in place so the roll pin can be driven further in. If you do not use something to align the catch holes for the pin you will drive yourself nuts. Another option is to use a 3/32 drill bit’s smooth end to help line things up by inserting it through the front hump.
Use the pin punch to keep the catch properly positioned as you drive the roll pin through. Just short of bottoming out the starter punch, use a pin punch to drive the pin in the rest of the way.
Next, you need to use the roll pin punch and a small hammer to drive the pin the rest of the way in. You can use the Wheeler block to hold the receiver or whatever works for you. Having a firm support makes it much easier. My Astro Pneumatic roll ping punches are long. My 1/8″ punch is 7″ long so I would recommend looking for something like that so you can clear the receiver when you are hammering the pin all the way in. I don’t think the Astro set I have is made any longer because I could not find it on Google to share with you. I use my Tekton punches.
With that you are done. You can function test the unit by pushing on the top paddle. You should feel the spring compress and release as you rock the catch back and forth.
If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@ro*********.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.
AR Parts Sources
There are a lot of reputable AR parts vendors online but beware of eBay and bargain basement dealers that sell airsoft parts and tell you they will stand up to firearm use – they will not. At any rate, here are my top sources of AR parts:
Just a quick note – when you get a bare receiver, you are literally getting a chunk of aluminum with nothing installed. I really like Palmetto State Armory (PSA) lower build kits and they sell them with different types of components such as just the basics for rifles, for pistols, Magpul furniture, etc. What I like is that the machining is very good and I think they have some of the best Mil-Spec basic triggers that aren’t gritty. I’ve used Anderson and other brands of build kits and just think the PSA kits are superior. Bear in mind that I say this as a customer – nobody paid me to tell you this.
With that said, let’s start building. You’ll notice on any AR magazine on the right side there is a rectangular notch. This is where the magazine catch engages to hold it in place. Okay, so the first step is to install the magazine catch assembly. It’s made up of the “L” shaped catch itself, the mag catch spring and the magazine button.
Now I grease everything that slides with Tetra Gun Grease. Tetra has worked well for me but I also know guys who use all kinds of greases. As a rule of thumb, if it slides, apply grease. It it rotates then apply oil. So grease the shaft and insert it into the round hole on the right end of the recessed area for it on the right side of the receiver. Note, be careful when installing the catch or you may scratch your receiver.
When you turn it over you will see the threaded end of the shaft and you put the spring down over it.
Next, you will screw the magazine button onto the threaded shaft. Before you do, look at the button. You should see that one end is smooth (that is the bottom) and the other has grooves (that is the top). Carefully start screwing the button on but stop before you get near the receiver so you don’t scratch anything. Push the button in, and then turn the long lever arm to continue threading the shaft into the button. Now stop before the lever arm scratches the receiver.
To screw the catch in the rest of the way you need to push the bullet button in all the way so the catch sticks out as far as it can on the other side so the lever arm can clear the parts of the receiver as the button is screwed on. At this point, I use a small pusher tool made from plastic to push the button in even further so I can keep turning the lever arm until the screw is relatively flush with the top of the button. Note, before I had the tool I would use a wood dowel. Just use something non-metallic to protect the finish. There is a model of the tool shaped just like the oval button but I don’t know where mine went so I used a takedown tool and got the job done 🙂
The catch is now installed. To function test, push the magazine button. You should feel spring resistance and see the magazine catch’s lever arm push out. When you ease off the button, the lever arm should smoothly go back into place.
If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@ro*********.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.
AR Parts Sources
There are a lot of reputable AR parts vendors online but beware of eBay and bargain basement dealers that sell airsoft parts and tell you they will stand up to firearm use – they will not. At any rate, here are my top sources of AR parts:
If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@ro*********.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.
