AR pistol build and documentation

[bruner1981jpce]

Hey everyone. Happy New Year! I'm doing an AR pistol build to start off this new year and figured I'd document it here to prove its legality should the need arise.

So I've had my 80% lower sitting in my closet finished since I machined it back in July of 2014. I had plans then to build it as a pistol, but being an unemployed college student, my little funds had to go elsewhere at the last minute and my build got put on hold. Now that I've got some part time work I've been able to save up the funds to finally finish it.

This firearm started life as an 80% lower, and will be built in a pistol configuration as a single shot only. To make it a single shot only, I will be building it as a break-top and bolt action pistol. The following pictures will show how I will accomplish this.

I had a spare magpul 10 round magazine laying around which I have blocked to hold only one round and riveted the floor plate of the magazine to the base plate of the spring so that it cannot be reopened.

2016-01-07 21.49.16 by bruner1981jpce, on Flickr

2016-01-07 21.50.06 by bruner1981jpce, on Flickr

2016-01-07 21.57.59 by bruner1981jpce, on Flickr

To make the pistol a break-top bolt action, I have cut a length of a dowel to put behind the buffer in the buffer tube. Having the dowel behind the buffer will force me to remove the rear takedown pin and open the pistol, before I can pull the charging handle to open the action to eject the spent round and load a new one. I understand that this method can have some inherent safety issues if done incorrectly. When building this pistol as a break-top bolt action, I will not be installing a gas tube, and I will install the gas block in such a way that it blocks the gas port on the barrel, so no gases will flow through the gas block or back to the action of the gun. Here are my pictures of the installation of the plug behind the buffer.

2016-01-07 22.13.50 by bruner1981jpce, on Flickr

2016-01-07 22.14.25 by bruner1981jpce, on Flickr

Here is a picture of the magazine lock installed on the lower, locking the one round magazine in place.

2016-01-07 22.14.54 by bruner1981jpce, on Flickr

And here is a picture of my completed pistol lower with the Sig brace installed.

2016-01-07 22.33.12 by bruner1981jpce, on Flickr

Hopefully my upper parts will be delivered tomorrow. They shipped yesterday via USPS 2-day shipping, but I guess they are just choosing to not update the status of that package, since it still only shows as "Picked Up". More pictures to follow when the parts arrive.

EDIT: Pictures fixed

[RosevilleGunner]

Great post. I will be following in your foot steps soon with my own build. Looking forward to seeing the finished product.

[stix213]

I like what you're doing, but a 1 round mag would give a capacity of 1 + 1, so wouldn't be single shot unless I'm misunderstanding what you're doing. I did something similar with a mag but made it hold 0 instead of 1. It looks possible in your setup to have a round in the mag and in the chamber at the same time, so not single shot. IANAL

[bruner1981jpce]

I like what you're doing, but a 1 round mag would give a capacity of 1 + 1, so wouldn't be single shot. I did something similar with a mag but made it hold 0 instead of 1.

Thank you for the input. I had thought of that after I blocked and riveted it and did get slightly concerned.

However, after I thought about it a little more the conclusion I came to was this: Since I put the plug behind the buffer tube, it's no longer possible to cycle the action with the gun closed, I have to separate the upper from the lower by removing the rear takedown pin. When the upper and the lower are separated in that way, the gun cannot feed any ammunition from the magazine. A magazine is defined as an ammunition feeding device, but in my gun, it will not function as such. So in that case it seems like it becomes just a redundancy to cover my butt (I hit the sensor, my apologies) if any questions about legality come up.

Did all of that make sense or was I just completely off the wall again?

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[JDMIS300]

Thank you very much for this documentation. This will be extremely helpful to the forum and folks with experience can add in their opinion as well.

[Maltese Falcon]

I got around having to mess with the buffer and modifying a mag by using this one shot sled. Pricy but meets the intent.

https://www.midwayusa.com/product/967912/original-bob-sled-loading-block-ar-15

Good luck with the rest of build!

.

[chiliman21]

My understanding is one in the chamber one in mag is not a single shot. My 2 cents. Good luck with your build.

[radicalray]

Use vise block 9.99

http://www.plastixrevolution.net/products/receiver-vise-block?utm_medium=cpc&utm_source=googlepla&variant=335228068&gclid=CIC6oKSWm8oCFZKCfgodhOMDqQ

[gvelas2A]

This is a great thread that I will bookmark now. Thanks for deciding to do this as it will be valuable to me when I start machining of my 80% lower and purchase and build my lower receiver after my financial aid check comes in next month. I totally understand the whole college student thing. keep up the good work. BTW What trigger do you have? And is a Gissele stage 2 trigger really worth it?

[hossb7]

This is a great thread that I will bookmark now. Thanks for deciding to do this as it will be valuable to me when I start machining of my 80% lower and purchase and build my lower receiver after my financial aid check comes in next month. I totally understand the whole college student thing. keep up the good work. BTW What trigger do you have? And is a Gissele stage 2 trigger really worth it?

Yes.

I have an SSA-E that I bought on sale from Primary Arms for 25% off.

Worth every penny.

[skyungjae]

I modified a 10 round magazine to be a single shot sled too. I used disposable chopsticks to keep it from being able to accept a round, but still be able to lock the bolt back after the shot was fired. You'd have to use the bolt catch release to make the bolt go back into battery as pulling the charging handled obviously wouldn't do anything.

[gvelas2A]

Yes.

I have an SSA-E that I bought on sale from Primary Arms for 25% off.

Worth every penny.

Nice thanks HossB I have their website bookmarked and will purchase it when funds are available.

I have been on the fence about either buying a DDM4V3 or building one from a stripped lower and the latter won. However, I don't know if I should go with a Daniel Defense upper or Ares Armor upper. Choices choices.

[bruner1981jpce]

This is a great thread that I will bookmark now. Thanks for deciding to do this as it will be valuable to me when I start machining of my 80% lower and purchase and build my lower receiver after my financial aid check comes in next month. I totally understand the whole college student thing. keep up the good work. BTW What trigger do you have? And is a Gissele stage 2 trigger really worth it?

Thank you everyone for the advice and the support!

The trigger I am using is an ALG ACT trigger. It's a Mil-Spec, nickel boron coated trigger. ALG is an offshoot company of Geissele, and the ACT trigger is tuned by Geissele, so I'm told. They usually run about $65 and are awesome triggers. Still a Mil-Spec trigger pull weight, but it's a smooth pull with a crisp break. For a budget build, it beats the heck out of the standard Mil-Spec triggers.

Anyways, based on the advice, when I get home from work I will either redo my mag block to hold no rounds or use the vice block I have instead, if it will fit in the gun with the action closed.

Thank you again everyone!

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[BigPimping]

Glad i just bought a registered lower. Great post though.

[gvelas2A]

I am on the fence about either buying or building my first AR. I have some experience shooting it and there is a lot of debate on this. I would buy my first one which would be an entry level like M&P15 or build one from scratch which would be more expensive, but I would add everything I want on it. I know that if I do go with an entry level I will end up upgrading it anyway which would make a 700 AR become a 1200 dollar one. I would start with a Warrior 1 lower. Suggestions?