Polymer Receivers

[mtnman31]

I've got a New Frontier Armory polymer lower I got a few years back. It has worked fine for me. It's been under 5.56, 300 Blackout, and .458 SOCOM uppers. No issues or problems with performance. My only complaint is that the opening on the raised boss for the bolt release is just slightly wider than it should be. The result is some minor back/forth slop with the bolt release. It's a minor issue considering the cost of the lower.

[white eagle]

I had a composite lower for my ar15
my son now owns it
I never had any issue's with it worked just fine

[abunaitoo]

A while back I remember trying a plastic AR.
Forget what brand.
I remember it did reduce the vibration and twanging sound.
Other than the weight, it was no different from my Colt H-bar.
Friend has a 3D printer.
It's so slow.
Kind of like watching a plant grow.
But would be nice to play with one.

[Bazoo]

The original bushmaster made a polymer AR for a while. I don't recall the name of it.

[Bodean98]

I used a polymer 80 lower until it broke. Buffer tube area. 300BO in less than 1000 rounds.

[bruce drake]

I used a polymer 80 lower until it broke. Buffer tube area. 300BO in less than 1000 rounds.

Its pretty easy to print off spare lower receivers. I keep one handy for whenever my other polymer receiver breaks or cracks. swapping out the FCG and stock parts is under an hour. 3d printing the recevier takes about 12 hours. set it and forget it like a slow cooker.

[CarlMc]

The design for the AR was optimized to be made from aluminum. If the design had been optimized for a variety of polymers available at the time, it would have looked a lot different. Modern polymers are pretty incredible, but the rule about designing for the material is still a rule. What we've all been talking about is taking an aluminum design and attempting to make it work for polymer. You can't duplicate the pattern in polymer, you have to redesign it from the requirements, which is far easier said than done.

[jonp]

I've run a few for several thousand rounds with no problems including a couple of 80% lowers I built. Too bad I lost them in a canoe accident

[djlwest]

A polymer lower does not bother me nowhere as much as a polymer upper.

[DDriller]

As Texas by God said the Cav Arms lowers work well. Brownells has a new one out that looks nice the KP-15.

[Lloyd Smale]

where do you buy a 3d printer for under 200 bucks that will do one??

[Big Tom]

Check out fleebay. I have been using the "Anycubic" brand printers for 4 years now and they are inexpensive and produce decent results. (there is one on sale for $109 incl. shipping at the moment). For filament, I suggest using PLA, which is easy to use and about $20 per 2 lbs. Microcenter.com and Amazon.com are best sources for the filament.

where do you buy a 3d printer for under 200 bucks that will do one??

[bkbville]

if polymer worked for Glock, why shouldn't it work for Stoner?

(There are 3 types of pistols left in the world. 1911's, Glocks, and Glock copies.)

I have had a few synthetic lowers.

I first had bought a couple of New Frontier LW-15's (Light Weight 15) that worked quite well, and with a lot of different uppers - .223, 30BlackOut, and even .458 SOCOM. It took some weight off the rifles, which was nice, and actually had one with a plastic trigger group
and hammer that worked quite well - believe it or not (can't remember if that was the LW15 or not.)

The second one I had was an ATI lower that simply broke in half the first time I fired it. I don't know why, and neither did ATI. They took it back and refunded me. This was a disaster, and I think they got out of the business.

I still have another New Frontier LW-15 that is on my disturbingly ugly (New York State's fault - not New Frontier) AR, and that works
great. I don't, however attempt to test it's limits - but I don't do that with aluminum lowers either.

I'm comfortable with these, especially as I like light weight builds.

Now.. 3D printed? No way. Having done a fair amount of 3D printing - I'd just never trust the process on any (currently) affordable printer. They are imprecise (hard enough to make a round hole), and you would have to be very careful about material selection (PLA ain't going to cut it.) Someday? yes (and maybe today if you have all high-end stuff.)

I was more enthralled with the idea of casting a lower but I don't know what became of that.

[Texas by God]

DDriller, thanks for the heads up about Brownells kp15. The video is interesting and they look like a good start- if one can find the rest of the parts needed nowadays. The grip looks like an improvement but the loss of the butt storage and the extra sling holes don’t thrill me. But I would definitely build on one. It’s interesting that they recommend Not using the bigger AR15 compatible “thumpers”.

[Lloyd Smale]

Now.. 3D printed? No way. Having done a fair amount of 3D printing - I'd just never trust the process on any (currently) affordable printer. They are imprecise (hard enough to make a round hole), and you would have to be very careful about material selection (PLA ain't going to cut it.) Someday? yes (and maybe today if you have all high-end stuff.)

Is this opinion based on an actual failure or experience or just an opinion? Im more interested in talking with someone who tried it and it failed then just conjecture. I have absoultey no experience with 3 d printing but do have a poly80 ar and the people on here that know me know I SHOOT. Mine has held up just fine. Not one bit of problem with probably 5k on a 556 upper. I own blackouts too and the differnce between them and 556's in recoil isnt enough to talk about.

[Big Tom]

You can get 3D printer designs that enforce the weak areas like the buffer tube attachment and upper pin holder areas. PLA is just fine for it (and yes, I have been 3D printing things for 5+ years now and that included a few lowers). I agree with the accuracy of the pin holes, but nothing a drill could not fix. You also need to be careful when installing the pins so you don't break the rather brittle plastic - but there are even modular designs that allow you to just re-print the part that you broke.

I am using my 3D printed lowers primarily for the .22 LR conversion kit ARs, but they could be used for .223 as well. Not sure about the more powerful rounds.

My personal choice is aluminum, then commercially re-enforces plastic lowers, then 3D printed lowers - and no plastic in the AR I used for home protection.

Is this opinion based on an actual failure or experience or just an opinion? Im more interested in talking with someone who tried it and it failed then just conjecture. I have absoultey no experience with 3 d printing but do have a poly80 ar and the people on here that know me know I SHOOT. Mine has held up just fine. Not one bit of problem with probably 5k on a 556 upper. I own blackouts too and the differnce between them and 556's in recoil isnt enough to talk about.

[Elkins45]

I have a GWACS integrated lower and love it, but it was designed from the beginning to be a polymer gun. The ones that simply copy the aluminum design in polymer tend to snap off at the receiver extension. With a 16” pencil barrel you can put together a nice rifle that’s less than six pounds.

[Lloyd Smale]

The original bushmaster made a polymer AR for a while. I don't recall the name of it.

that was the carbon 15 and i think the upper and lower were carbon fiber