So there I was trolling the interwebs this weekend and stumbled upon some ATI Omni polymer lowers for roughly $70 a pop. Now my question is anyone know anything about these polymer lowers?
Do they stand up to the kind of abuse billet or aluminum lowers take? Are they worth it and anyone run one now?
For a dedicated rimfire… maybe. 
Even then, I wouldn’t take one for FREE. No joke.
I’ve got one en route from PSA. I’m going to try it out for a while and see how it does. But no experience with one as of yet.
Please post your results here I am interested to see any/all results.
Hey Markm, how do you think a poly lower would hold up to the big boy 450 BM, 338 Federal, 7.62 NATO guns? :eek:
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Polymer receiver designs still need refining
Will do. It’ll probably be a few months though.
Ouch. I’ve seen my share of busted lowers also.
Got that right. I fix local yocals’ AR’s around here and the last 2 I worked on had poly lowers and uppers. The uppers just plain suck. One I had in my Brownells upper vise and while torquing the barrel down (40 lbs) I could see the upper flexing.
The other was a Bushy Carbon 15 where the guy wanted to replace the poly upper with an aluminum one. The Carbon 15 doesn’t even have a stock barrel nut. It looks just like a typical AR nut but will not thread up to a standard receiver. Its too large. Not to mention no forward assist or ejection port cover.
The poly lowers don’t allow mags to drop with ease. Especially PMAGS. At least in my experience. Maybe a bit of fine sandpaper would remedy this.
-Jax
I did a light weight build and used a 109$ complete NFA lower for the weight savings. Even with a light weight profile 14.7 pinned and welded barrel it is front heavy.
The weight savings experiment did not pan out,
use me as an example of that.
Will life time warrantied and holding up to some 5.56 recreational use,
I do not recc. it as a cost savings. 100$ saved on a total build vs. a forged lower?
I wince at the thought of having to slam the butt into the ground to clear a mother of all jams or something.
One of those seemed like a good idea at the time builds…
It’d be ideal. The recoil would be minimal too. 
I’ve seen the threads strip where they bolt the rail on to the upper.
They’re probably stronger than paper mache’ lowers but I wouldn’t know for sure.
ETA: I was just thinking, they would make for a great party favors. You could hang them by the carry handle with a string, let “kids” beat on it with a stick and watch them scramble for a Pmag & BCG.
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I think it’s reasonable to look at the application and see if it’s appropriate.
People can laugh all day at polymer lowers, but many of those same people think a forged lower stamped “Colt” is maybe 5 or 10x stronger than a forged lower stamped “DPMS” or something. They are wrong. I’m not saying it’s wrong to choose known quality, but a 7075 forged lower is a 7075 forged lower from a strength standpoint, and with some brands you can expect slightly better fit and finish than others, that’s all.
But you’re talking about polymer lowers. I have 3 guns with forged lowers, 1 with a 7075 billet lower, and 1 AR-10 forged (not that extruded DPMS fakeAR-10 stuff). I also have a New Frontier polymer lower plinker. Guess what? It’s fine. Would I issue it to a soldier in a combat zone, or even a patrol officer? No. Because the military has tested and proved, updated, tested and proved, etc. the forged lower for 50 years.
The lower is not a part that sees any significant stress unless you are buttstroking with it. A polymer upper is a poor application if the dimensions are similar to that of a forged 7075 upper, since the upper must survive being clamped with tremendous force to the barrel. I have seen “milspec” 7075 uppers fail too; they are very thin around the ejection port and can be flexed with your bare hands. Is the aluminum then mis-applied? It depends on your expections - remember that originally they had a carry handle, a pencil barrel, and were not suitable for optics, so they were stronger and receiver flex would not affect accuracy.
I’ve built 4 of the plastic lowers so far, and sold them to guys that might go shoot targets once a year. They wouldn’t have spent more, but are now supporting the industry and voting for gun rights. I wouldn’t make fun of their choice for a second, considering their alternative would’ve been buying nothing. Most will graduate to nicer stuff I suspect.
Besides this there are literally hundreds of industrial polymer formulations, and good engineering practice would tailor them to the application. I think the original Vulcan? and Bushmaster stuff was not what it could’ve been with good engineering. The NF stuff actually works very well, it just lacks fit and finish. There are areas where it deviates from the mil-spec dimensions in order to strengthen roll-pin bosses and such.
My point is this, making blanket statements about how stupid anyone is for buying a polymer receiver is ignorant and only serves to embarrass new people away from supporting and industry that is constantly under attack. I don’t expect your casual plinker that wants a lightweight $800 AR is going to suddenly begin serving on the SWAT team with that weapon.
VIP3R,
If I take your new avatar correctly did you and yours just have a baby?
If so that’s awesome and congratulations brother!
-Jax
A polymer lower designed correctly could provide certain benefits over an aluminum lower. Problem is, all the polymer lowers I’ve ever had it looked like the manufacturer took a standard aluminum lower, built an injection mold off of it and said “F&*^ it, good enough!.” Acting as if even good polymer is equivalent to aluminum is not going to work out well.
It’s just like when aircraft manufacturers started using carbon fiber composites. They treated the stuff like black aluminum and the end result was craptastic. Once they started using the materials for what they were and not what they wanted to them be, the results were significantly better…
NFA is local to me and I know that they seem to be good folks and they do offer a lifetime warranty on their lowers. The only issues I have heard with them are certain LPK’s not fitting right (specifically the bolt catch and take down pins).
Thank you,
This was a much more efficient way to make the point I meant to make. I’m an engineer, we are good at understanding such things, but have to work extra hard to communicate properly.
A good polymer receiver should be darn near a ground-up design, constrained by the critical internal dimensions and parts compatibility.
I’ll try again: aluminum does not make it good, polymer does not make it bad. Good design and practices make it good, bad makes bad.
It always grinds me when people are so goddam smart about aluminum receivers also, with things like this:
-“billet receivers are better” Are they? What is the material, alloy, and heat treatment? What areas have been strengthened to surpass the strength provided by forging? Did you get an extra special Zombie logo machined into the 6061 “aircraft aluminum” magwell?
-“Forged receivers are the best” What’s your application? How long and heavy is your barrel? Are you mounting optics? For example, I’ve been seeking Vltor MUR or Mega billet uppers to do a couple of builds with heavy barrels, long-range, large optics. The point here is stiffness from bore to scope. The military “flat-top” A3 upper is made for a gun with a relatively lightweight, 14.25" barrel and 1x optics or irons.
-“If it doesn’t have a dancing horse on it, it had better say BCM or it’s crap” I have lots of respect for those brands, who are committed to quality control and reputation. However, nearly all of the brands by forged blanks from the same small group of forging suppliers. If these are CNC-machined to within the tolerances, the receivers will be functionally equivalent.
Of course, the world is full of people who spend $30K on a car and start replacing functional components with chrome parts off of ebay, you know, because us engineers are a bunch of f’n idiots and didn’t make good choices.
:D:D:D Yep! Thanks. I’m pretty much the happiest man alive right now. We named him Jax which i’m sure you approve of.
Depends on what you do as an engineer as to whether the communication comes or not. 
I spend my engineering days convincing people to do that which they do not wish to do so I have to be able to get my point across clearly without upsetting their tender sensabilities :sarcastic: