Seems these are pretty cheap and are actually available if you look around. (MidwestPX)

 

But, what are they? Are they decent? Are they strictly for 22s? Are they junk?

 

What's the deal?

I have a New Frontier lower pn a stag model 1 upper. 500 rds and no issues. I ve also seen some pix on the web that show cracked polymer lowers but i dont think there willl be issues long term. Fits really tight on the upper.

 

Working on a 2nd build now , some members here have experience in putting the parts together but with some issues

 

Read here:

http://njgunforums.c...__fromsearch__1

Lightweight. How do you feel about polymer pistol lowers? See my point big guy.

I don't own one but think about all the handguns built using poly frames now. Can flex but won't warp . A guy I work with has a poly lower AR in 5.56 and has a few hundred through his with no problems. ( I know, not a torture test). New Frontier has a video on youtube torture testing their lowers

 

I don't think the strength of the polymer is really an issue anymore. But if you read the link Damjanblues posted, if you plan to assemble your own lower be ready to dremel and file, and test it, and re-file, and dremel some more.

All those polymer handguns have steel inserts and the stresses are distributed differently then an AR lower. That is not to say that you couldn't make a decent one, its just that it is not as simple as saying because handguns work, so will rifles.

makes me wanna cry seeing them destroy that poor forged lower lol

I had a Plum Crazy that I had 556 upper on. I shot it a bunch of times but I always had that thought in the back of my head saying this is polymer and I had doubts. i have since used the lower on a .22 build and bought a Spikes lower for my 5.56. The things I have read many people get a lot of hard use out of them.

makes me wanna cry seeing them destroy that poor forged lower lol

I'm sure when they made the video that lower was half the price of what it would go for today. so sad

The New Frontier lowers are an improved version of the Plum Crazy lowers. They were reinforced in the areas where the PCs would break/crack. They're fine for 5.56 builds because a lower receiver really doesn't see that much physical stress. Sometimes, they require a little hand fitting when installing a LPK but nothing extreme. One of the things that most people rave about as a positive is due to the nature of the manufacturing process, the fit between upper and lower when using a NFA lower is that it's super tight. Yes, the original AR design was intended to have some small amount of play however the commercial market has spoken loud and clear that it wants tight fitting receivers.

MidwestPX:

 

Would YOU use one for self defense?

MidwestPX:

 

Would YOU use one for self defense?

 

I personally wouldn't use any home built rifle for SD, not even the ones I build. My HD carbine is one direct from LMT. The one that rides in my vehicle is a Daniel Defense.

 

When I build a rifle, it's a range gun. I may run it in a carbine class just to run the gear hard but my defensive guns are built by a factory. Could I pick up one of my builds and use it? Sure. Do I want to? No. Why? Because I don't have the same QA/QC protocols that top tier manufacturers do. It has nothing to do with the quality of parts.

Had a Cavalry Arms lower years ago that I put a few thousand rounds through without issue. Sold it because I like to modify and make stuff mine, and with a one piece design with pistol grip and stock, there wasn't a lot of room for customizing and fitting. As I recall, there have been several articles over the years that basically state the AR lower receiver isn't imparted any significant stress as a result of the firing cycle, and basically just holds things in the right spot to allow functioning. It's one of the reasons folks have been able to make functional lowers on 3D printers more recently...

I personally wouldn't use any home built rifle for SD, not even the ones I build. My HD carbine is one direct from LMT. The one that rides in my vehicle is a Daniel Defense.

 

When I build a rifle, it's a range gun. I may run it in a carbine class just to run the gear hard but my defensive guns are built by a factory. Could I pick up one of my builds and use it? Sure. Do I want to? No. Why? Because I don't have the same QA/QC protocols that top tier manufacturers do. It has nothing to do with the quality of parts.

 

This is an assumption on your part. I bet a carefully assembled rifle with the same quality parts are equal. Your hand assembled isn't rushed through an assembly line. You probably hand build a fine rifle.

 

Now I see your a class 03 dealer I'm not referring to that in anyway as I don't have a knowledge base there.

Had a Cavalry Arms lower years ago that I put a few thousand rounds through without issue. Sold it because I like to modify and make stuff mine, and with a one piece design with pistol grip and stock, there wasn't a lot of room for customizing and fitting. As I recall, there have been several articles over the years that basically state the AR lower receiver isn't imparted any significant stress as a result of the firing cycle, and basically just holds things in the right spot to allow functioning. It's one of the reasons folks have been able to make functional lowers on 3D printers more recently...

 

Not quite true. The 3d printed ones have been breaking after 6 rounds or so, and anything that holds things together, does have some stresses on it. It isn't just the firing either, if you actually shoot your rifle not just from a bench, you will put lateral stress from your off hand, you will rest it against something, etc. Now look at how much material is actually holding the upper to the lower, and ask yourself if you really want that to be plastic without some metal inserts?

This is an assumption on your part. I bet a carefully assembled rifle with the same quality parts are equal. Your hand assembled isn't rushed through an assembly line. You probably hand build a fine rifle.

 

Now I see your a class 03 dealer I'm not referring to that in anyway as I don't have a knowledge base there.

 

Considering they're using pre-set, electronically-controlled, self-logging torque drivers (for instance) while I have a Sears/Craftsman torque wrench, I think it's safe to say they have better QA/QC than I do. The fact that they even have a dedicated quality department would suggest that. Additionally, as an example, LMT is ISO certified. It wouldn't surprise me if their quality department was on the path to a TS cert as well.

Considering they're using pre-set, electronically-controlled, self-logging torque drivers (for instance) while I have a Sears/Craftsman torque wrench, I think it's safe to say they have better QA/QC than I do. The fact that they even have a dedicated quality department would suggest that. Additionally, as an example, LMT is ISO certified. It wouldn't surprise me if their quality department was on the path to a TS cert as well.

 

Having worked for a defense contractor with a QA/QC dept I'm sure you personally as a craftsman are are capable of doing an equal or better job. Now I'm not talking about you doing your own nondestructive testing. I'm saying assembling.

 

Thank you for your input.

 

Now back to polymer lowers... Not for me.

To be fair, almost anyone can get an ISO certification (I'm assuming you mean 9000/9001) because it is more concerned with having a processed and following it, and less with what results from the process.

 

I think confidence is the most important part. I doesn't matter if you built your rifle or some big name brand built it, as long as you are confident in its performance. Obviously I don't mean blind confidence, but informed confidence. I build my own rifles, and I'm confident in their performance, because I drag them to 3gun matches, and I shoot them dirty, dry, in the mud, in the snow, etc. as much as I can. I have more trust in a rifle I use regularly then in one that came from a big name factory that doesn't get used a lot. But that's me, and I wouldn't fault anyone for thinking differently.

I'm sure you personally as a craftsman are are capable of doing an equal or better job.

 

I would say a calibrated one is, but you have probably seen it also, but I can't believe how many people don't zero their TQ wrenches after they use them, let alone have them calibrated every so often..

Speaking of which, and a massive thread drift, where does one get a TQ wrench calibrated, I need to have mine checked.

Speaking of which, and a massive thread drift, where does one get a TQ wrench zeroed, I need to have mine checked.

 

When I say zero their TQ Wrench, I mean after you use it, set the TQ setting to zero, keep them set at what use it for isn't good for them.

 

As far as testing them, here is a real quick and while not as precise as real testing equipment, take your old beam style TQ Wrench and test it against that. Easiest way would be to TQ something to a known setting with the beam and then check it against you other wrench.

 

Also I am not sure if they have it on them, but some of the Snap-on trucks that used to pass by the Hanger here at the airport used to be able to check and calibrate their wrench for the guys. It's been a while and I haven't been on a Snap-on truck Wonder Land in a while, but they may still be able to check yours if you see one a a shop or repair shop.

Yeah I meant calibrate, not zero, I edited my post. I found a few online places that do it, but for the cost plus shipping I'm better off buying a new one and it wasn't cheap to start.

3d printed stuff is meant for looking and handling, not for actual usage.

 

Not quite true. The 3d printed ones have been breaking after 6 rounds or so, and anything that holds things together, does have some stresses on it. It isn't just the firing either, if you actually shoot your rifle not just from a bench, you will put lateral stress from your off hand, you will rest it against something, etc. Now look at how much material is actually holding the upper to the lower, and ask yourself if you really want that to be plastic without some metal inserts?

I own 3 NFA lowers. I have 650 rounds through 1 and about 200 rounds through the other 2. I have not experienced a single malfunction.

 

2 were complete lowers and the last one was stripped. I put a PSA LPK in the stripped one. I did have to file the mag catch hole a little for proper fit, but that was it as far as quality issues.

 

The NFA triggers are actualy quite crisp.

 

I would buy more if the prices had not sky rocketed so much.

Interesting responses, thanks gentlemen.