AR pistol build

After a visit to the 2A candy store, I was handling a LWRC AR pistol with the brace.
Wanted it but sadly funding issues.
I do have a lower pre if it could save one child law.
Question is can I build a pistol with that lower?

Tod said:

After a visit to the 2A candy store, I was handling a LWRC AR pistol with the brace.
Wanted it but sadly funding issues.
I do have a lower pre if it could save one child law.
Question is can I build a pistol with that lower?

Click to expand...

As long as it didn't start out as a rifle first, you can build it into a pistol.

Tod said:

After a visit to the 2A candy store, I was handling a LWRC AR pistol with the brace.
Wanted it but sadly funding issues.
I do have a lower pre if it could save one child law.
Question is can I build a pistol with that lower?

Click to expand...

If you purchased the lower as a stripped lower from a dealer than you can build it into a pistol as long as it was never built as a rifle. The dealer should have logged it as a receiver when it came into the store. When the dealer transferred it to you they would have checked “other firearm” in block 16 and written receiver in block 27.

At pistol can become a rifle and revert back to a pistol but a rifle cannot become a pistol ever. If you want to shorten a rifle you must go the NFA route and make it a Short Barreled Rifle.

Tod said:

After a visit to the 2A candy store, I was handling a LWRC AR pistol with the brace.
Wanted it but sadly funding issues.
I do have a lower pre if it could save one child law.
Question is can I build a pistol with that lower?

Click to expand...

Yes, if that lower has never been built as a rifle (as others have already said).


However, I wouldn't do that. Save that lower for a pre-ridiculous law rifle build.
Buy a new receiver for a pistol build. They aren't that much.

Major03 said:

Yes, if that lower has never been built as a rifle (as others have already said).


However, I wouldn't do that. Save that lower for a pre-ridiculous law rifle build.
Buy a new receiver for a pistol build. They aren't that much.

Click to expand...

Au contraire Pierre. Always build a 'naked' lower into a pistol first, then do whatever...

outrider58 said:

Au contraire Pierre. Always build a 'naked' lower into a pistol first, then do whatever...

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Bingo! You win the internet today!

Thanks for the info.
Now the research begins
Model, DI or piston, barrel length and of course the $$ thing.
Any experienced opinions welcome

Tod said:

Thanks for the info.
Now the research begins
Model, DI or piston, barrel length and of course the $$ thing.
Any experienced opinions welcome

Click to expand...

My experience is somewhat minimal in building but I can at least throw this much out there for you. The route that I went with my half a dozen or so pistol builds was building the lowers first. You can easily buy a completed upper if you wish at a later date. The lower is extremely easy to assemble. a few specialty tools makes all the difference. I followed several different sources but good ol Larry Potterfield of Midway USA made a simple, easy to follow video on his website here...

https://www.midwayusa.com/general.mvc/index/how-to-build-ar-15-rifle

The only steps that need a little bit of tweaking comes in at the end. You will be assembling a buffer tube or pistol brace instead of a stock therefore you need to reverse the last 2 steps.

I splurged on 3 of my lowers with drop-in triggers. Velocity makes a nice economical upgraded trigger. They offer 3 or 4 pound trigger pulls. My Elftmann 3 gun was a tad more expensive.

KNS anti-walk/rotate pins are a nice upgrade to your lower parts kit. That kit will keep your trigger and hammer pins in place, no worries.

2 of my builds I also splurged with an SB Tactical PDW arm brace. It's as close to SBR as you can get without being an SBR. They are in the same neighborhood...same zipcode...they practically live right across the street from each other.

Oversize trigger guards are a nice, inexpensive upgrade as well. They make shooting with large fingers or gloves comfortable. I am fond of my Timber Creek Outdoors trigger guards. They are anodized aluminum and come in many colors.

Another easy affordable upgrade is a grip. I am fond of the Hogue overmolded rubber grips with finger grooves and beavertail.

it is nice to have an idea of the caliber you want to be firing and what barrel length/gas system length you prefer before you start building your lower as well. It will help you decide what weight buffer to use up front. You might have to experiment with buffer weights after your build is complete.

As far as Direct Impingement vs piston systems, I would advise you to stick with direct impingement for your first build. Pistons systems are mostly proprietary where as direct impingement systems are very modular. I have yet to build an upper for any of my pistols yet. I have been doing a lot of researching too. I have a very good idea of what I want to buy/build but I am not throwing any advice out there on that part since i have no experience in that department yet. Right now as far as building an upper is concerned, I only know what I have been reading. One simple piece of advice in regards to the upper, spend your money on a good barrel. From a newbie builder to a newbie builder.... I hope that you have fun with it! Keep us abreast of your findings and builds!

Tod said:

Thanks for the info.
Now the research begins
Model, DI or piston, barrel length and of course the $$ thing.
Any experienced opinions welcome

Click to expand...

If it is to be an AR pistol, please Please PLEASE do not got piston. Go DI. A standard built AR is not set up for aftermarket piston operation. Bolt tilt and quicker unlocking times are but a couple problems that will lead to problems down the road.

If you seek a piston gun, it is wiser to buy a gun manufactured to be a piston gun. Unless you 'operate' in an aquatic environment, the piston offers no added benefits over the DI guns IMHO.

I was told that anti walk/roll pins are not good at all. I was told the pins were designed to spin in the holes.

Am I correct ?

boothdoc said:

I was told that anti walk/roll pins are not good at all. I was told the pins were designed to spin in the holes.

Am I correct ?

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With standard type FCGs, yes. For 'drop-in' pack type triggers, I'm not sure.

I have already built up my black rain lower with PSA parts. I would need to change out the buffer tube and buy a complete upper in pistol length.
I shoot a Sig 556, never any issues. Goes bang every time and chamber is nice and clean.

outrider58 said:

If you seek a piston gun, it is wiser to buy a gun manufactured to be a piston gun. Unless you 'operate' in an aquatic environment, the piston offers no added benefits over the DI guns IMHO.

Click to expand...

Tod said:

I shoot a Sig 556, never any issues. Goes bang every time and chamber is nice and clean.

Click to expand...

boothdoc said:

I was told that anti walk/roll pins are not good at all. I was told the pins were designed to spin in the holes.

Am I correct ?

Click to expand...

The KNS pins that I purchased are anti walk AND anti rotate pins. They are a gen 2 Mod 2. They have a a slot on the upper hammer pin which keep it from rotating. The lower trigger pin is attached with screws. You can easily see the slots on the upper pin but they are not easy to see on the dogbone in the link below. No spin, no walk = less wear on the receiver holes. That is the idea behind them. Someone chime in if i am wrong.

https://www.knsprecisioninc.com/product/gen-2-mod-2-build-kit/

Tod said:

Thanks for the info.
Now the research begins
Model, DI or piston, barrel length and of course the $$ thing.
Any experienced opinions welcome

Click to expand...

As said already Piston aftermarket systems are not the way to go if you are building a pistol. There is really no need to use a piston system in most if not all applications or use and a lot of the time reduce reliability because they are installed incorrectly. Put the money you would spend in a Piston system into better trigger, barrel and BCG.

Using a 10.5” or 11.5” barrel with a carbine length gas system is IMO the best way to go. This will reduce reliability issues and increase accuracy if you are building an 5.56. 8” barrels are fine if building a 300BO. Can you get a 7.5” barrel in 5.56 to run reliably, yes, but again you may find yourself very frustrated and constantly tweeking things to make it run or having to use specific ammo.

Kicken Wing said:

The KNS pins that I purchased are anti walk AND anti rotate pins. They are a gen 2 Mod 2. They have a a slot on the upper hammer pin which keep it from rotating. The lower trigger pin is attached with screws. You can easily see the slots on the upper pin but they are not easy to see on the dogbone in the link below. No spin, no walk = less wear on the receiver holes. That is the idea behind them. Someone chime in if i am wrong.

https://www.knsprecisioninc.com/product/gen-2-mod-2-build-kit/

Click to expand...

In a standard fire control group, you actually do want the pins to rotate. That does not effect the pin holes in any measurable way. If you have a problem with pins "walking" sideways out of your receiver, you have other problems than need to be addressed, like maybe a reversed hammer spring or a missing retaining spring.

Many pack triggers(drop-in) actually have roller bearings that allow the hammer and trigger to rotate around a stationary pin. KNS pins help in that regard.

Kicken Wing said:

The KNS pins that I purchased are anti walk AND anti rotate pins. They are a gen 2 Mod 2. They have a a slot on the upper hammer pin which keep it from rotating. The lower trigger pin is attached with screws. You can easily see the slots on the upper pin but they are not easy to see on the dogbone in the link below. No spin, no walk = less wear on the receiver holes. That is the idea behind them. Someone chime in if i am wrong.

https://www.knsprecisioninc.com/product/gen-2-mod-2-build-kit/

Click to expand...

The reason behind the rotation is for reliability. Most of the time you will rarely see much rotation of the pins. In the event any debris enters the lower receiver and becomes lodged in between the pin and the hammer or trigger and the pin isn’t allowed to rotate freely the weapon could malfunction causing a failure to fire. It was a redundancy built into the weapon system to ensure proper function of the rifle. If standard trigger and hammer pins are installed properly so the j-spring and the hammer spring seat in the recess of the pins then the pins should never walk out of the receiver.

Most of the time if your pins are coming out it is because the installation was done improperly or something is out of spec like the hammer or trigger holes are to big. The most common size trigger and hammer pins are .154” but there are some rifles like the Colt sporting rifle that use .171” pins. Best bet is to measure the hole to ensure you are using the right diameter pin.

Anderson is notorious for drilling hammer and trigger pin holes either to big or not big enough. Most of the time they make a decent product but there are always Monday and Friday receivers just like everything else that is machined in large quantities.

Thanks Outrider58 and retiredarmyguy for those clarifications. I will be sure to take that knowledge and store it for future builds. As far as my current builds, I luckily got it right!