an AR15 that comes in the mail

[Missourian]

3d printable lowers.

You mean a metal-printing machine? Haven't seen any for less than tens/hundreds of thousands of dollars.

I guess you can machine the lower, but the money for the machinery and the skill to acquire them would be almost insurmountable compared to "moving" to a different state, buying a gun as a resident, and "moving" back.

Lowers can be plastic polymer...not the most accurate due to flex...but useable. We have a built New Frontier and an AR1 eXtreme (unbuilt) poly lower.

What sort of polymer and printed with what? How many rounds can it handle before it breaks?

Thousands. The lower receiver isn't under any explosive pressure. The upper receiver, bolt carrier group, chamber and barrel do all the heavy lifting. Mine are commercial injection molded...but cheap printed models have survived hundreds of rounds. As more flexible printing medium becomes available, longer lasting printed lowers will be common place. At some point law will catch up to technology and a more load bearing component of poly firearms will become the serialized technical "firearm" I suspect...

As a range officer I see all kinds of ARs. I have seen several of the polymer lowers break near the buffer tube. That is the weak point because of the pounding. Some of the polymers nowadays have brass shavings in them and that helps a little bit.

I would never trust one for anything other than a .22.

I read somewhere that those failures were caused by overtightening. Not saying that is accurate...just remember reading it. My New Frontier has held up well...but I don't shoot it nearly as much as others due to it's inherent accuracy deficiencies.

The AR1 is reinforced...but that is good advice...it may become a 22lr. My wife appropriated the 1022...so I'm in need of a new semi-auto.

 

[abrere]

a private seller can always pick you out of a photo lineup. There's a jig that makes the job very easy,, even on the aluminum lowers, using a $70 router from Harbor Freight Tools. If you use the polymer lowers, you can easily do the job with a handheld drill, $15 harbor freight hand held electric grinder, and files. all you're doing is milling out a couple of pockets, really. One where the back takedown pin housing sits and one that's above the slot down into the guard, where the trigger-disconnector/hammer/selector sits. But yes, while you are at it, you should make at least 3 of them and bury them, after function testing. Then sell the jig and cutters on ebay or one of the gun forums. Everybody should have at least one fighting rifle and fighting pistol that nobody knows about.

 

[Flash]

You mean a metal-printing machine? Haven't seen any for less than tens/hundreds of thousands of dollars.

I guess you can machine the lower, but the money for the machinery and the skill to acquire them would be almost insurmountable compared to "moving" to a different state, buying a gun as a resident, and "moving" back.

Lowers can be plastic polymer...not the most accurate due to flex...but useable. We have a built New Frontier and an AR1 eXtreme (unbuilt) poly lower.

What sort of polymer and printed with what? How many rounds can it handle before it breaks?

Thousands. The lower receiver isn't under any explosive pressure. The upper receiver, bolt carrier group, chamber and barrel do all the heavy lifting. Mine are commercial injection molded...but cheap printed models have survived hundreds of rounds. As more flexible printing medium becomes available, longer lasting printed lowers will be common place. At some point law will catch up to technology and a more load bearing component of poly firearms will become the serialized technical "firearm" I suspect...

As a range officer I see all kinds of ARs. I have seen several of the polymer lowers break near the buffer tube. That is the weak point because of the pounding. Some of the polymers nowadays have brass shavings in them and that helps a little bit.

I would never trust one for anything other than a .22.

I read somewhere that those failures were caused by overtightening. Not saying that is accurate...just remember reading it. My New Frontier has held up well...but I don't shoot it nearly as much as others due to it's inherent accuracy deficiencies.

The AR1 is reinforced...but that is good advice...it may become a 22lr. My wife appropriated the 1022...so I'm in need of a new semi-auto.

I remember seeing a polymer crack the first time the guy brought it out to the range. I have seen about 4 or 5 crack after a few trips to the range. I also have a friend that has had one for three or four years with no problems.

New Frontier is a decent manufacture.

All the ones that I have seen crack have been at the buffer tube.

The only advantage of them is that they are lighter. They really don't have a cost advantage because the Anderson aluminum lowers are so cheap. I have seen them as low as $29.99. Most of the time you can get them for $39.99.

The only polymer I would get for a .223 AR would be the Cavalry Arms one piece. They are reliable.

 

[abrere]

like you said, it's just $40, and you most certainly CAN sell the other $500 worth of parts. and if push ever comes to shove, you'll be able to get $400 for that lower receiver, minimum and an entire AR might well get you a lb of gold, or a truckload of grain or legumes. Use a plastic welder to build up the weak points on the plastic receiver before you ever fire it. I recommend that everyone make a plastic one first, then do the aluminum one, after you know what you're doing.