FMK Polymer Lower is NOT GTG!!!

[eodinert]

Still trying to figure out why you'd mess with a plastic lower when metal lowers are so cheap...

[GSO]

We are stocking dealer of FMK, CMT, Spikes, LMT and Daniel Defense (most major brands of lower receivers.) Of the hundreds of FMKs that we have sold, we have not had one returned due to damage. We have seen Mil-spec major brands break, but never the FMKs. This looks like it was operator error over torquing the castle nut. I am glad that FMK responded with such an excellent, quick response. If we can help in any way, let us know. To show how much respect we have for the FMK receiver, send it to us with your parts and will assemble it, no charge, in tradition with FMK's service.

your a little late to the party.

This does seem like a strange offer by a mysterious new member so long after the original post.

Still trying to figure out why you'd mess with a plastic lower when metal lowers are so cheap...

For the same reason that Glock, Springfield, S&W, Ruger, Walther, et al, use polymer lowers.... Lower weight, less susceptible to corrosion, impervious to most chemicals, generally less affected by heat or cold, etc.

[claimbuster]

This thread has been good for me. I'm still a newbie when it comes to working on AR's and am just about to start my third lower build. So far, I've just been working with billet lowers. For number four, that will mate up with a 22LR upper, I was debating a polymer lower more for weight than anything else.

After reading this followed by reading more on the same topic elsewhere, I am going to stick with aluminum. After I go to the work of putting it together, I don't want it to come apart!

[chamrick]

We are stocking dealer of FMK, CMT, Spikes, LMT and Daniel Defense (most major brands of lower receivers.) Of the hundreds of FMKs that we have sold, we have not had one returned due to damage. We have seen Mil-spec major brands break, but never the FMKs. This looks like it was operator error over torquing the castle nut. I am glad that FMK responded with such an excellent, quick response. If we can help in any way, let us know. To show how much respect we have for the FMK receiver, send it to us with your parts and will assemble it, no charge, in tradition with FMK's service.

your a little late to the party.

This does seem like a strange offer by a mysterious new member so long after the original post.

Still trying to figure out why you'd mess with a plastic lower when metal lowers are so cheap...

For the same reason that Glock, Springfield, S&W, Ruger, Walther, et al, use polymer lowers.... Lower weight, less susceptible to corrosion, impervious to most chemicals, generally less affected by heat or cold, etc.

chamrick: As FFL dealers, we try to research our products from the manufacturing side and the consumer side. We look for products that customers are interested in and are giving excellent reviews; when we find reports of unsatisfied customers, we would like to help. No ulterior motive. As I stated, we have had excellent reviews on the product from our customers and we have had excellent reports from our time on the range with the FMK's. David at FMK has been nothing but the epitome of customer service. We also sell billet uppers and lowers; both the polymer and the billets have their place in the gun safe!

www.hamrickenterprises.com

[GSO]

chamrick: As FFL dealers, we try to research our products from the manufacturing side and the consumer side. We look for products that customers are interested in and are giving excellent reviews; when we find reports of unsatisfied customers, we would like to help. No ulterior motive. As I stated, we have had excellent reviews on the product from our customers and we have had excellent reports from our time on the range with the FMK's. David at FMK has been nothing but the epitome of customer service. We also sell billet uppers and lowers; both the polymer and the billets have their place in the gun safe!

http://www.hamrickenterprises.com

It struck me as a little odd (and annoying) that your first post to the forum is an accusation that one of the members over-torqued his castle nut. Not to mention the last post on the subject was over 3 months ago. In the very first post, it was stated that he's made 15 or 16 lowers, including 8-9 with NFA polymer lowers, so I'd think he has it figured out by now. Maybe he did overdo it on this one, but I wouldn't assume that based on the facts presented. It rubbed me the wrong way...

I'm also an FFL dealer, but non-stocking. I've sold quite a few LMTs and DS Arms rifles along with some DSA lowers, NFA lowers, and a few Windham rifles, so this ain't my first rodeo either. Not to mention carrying an M16 for quite a few years starting in 1980. My philosophy here has been to get a feel for the community and what the needs and interests are before I start pimping my wares. Maybe I'm foolish to consider my business an extension of my hobby rather than vice versa, but it works for me.

[Strontium90]

My only question is, "how much torque did apply to the Receiver Extension Nut." Did you use a Torque Wrench and what value did you use?

[Strontium90]

You have steered me away from ever buying one.
I thought it was odd that I never saw a .308 plastic lower. I have bought forged lowers as low as $70 before the panic.
it just never seemed like you saved enough $$$.

I just bought Four of them and work quite nice. My question about the broken one is what Torque Value was used to fasten the Receiver Extension Nut to the Receiver Extension Plate. My best guess was way too tight. These receivers have run on .50 Beowolf guns without fail so 5.56 is minimal.

[Strontium90]

Any thoughts on what may have caused, or lead to the failure?
I would assume that any polymer lower capable of handling the
5.56/.223 should be able to handle the 300 Blackout (within reason),
it being a low-pressure round and all. Yea, I know it is significantly
heavier, but it is not as violent to me when firing side-by-side
in similar configurations.

These receivers have been used on .50 Beowolf guns without failure. The problem with the Receiver Loop breaking is often improper Torque of the Receiver Extension Nut.

[Strontium90]

To be clear, the New Frontier lowers are ok, but the FMK are not.
My Carbon 15 lower has been through a lot and it still going strong...

I bought Four of the FMK Lower Receivers all of which work flawlessly. I do know that the Torque value for the Receiver Extension is different than a metal receiver and if you don't do it right you will cause a failure.

[Strontium90]

chamrick: As FFL dealers, we try to research our products from the manufacturing side and the consumer side. We look for products that customers are interested in and are giving excellent reviews; when we find reports of unsatisfied customers, we would like to help. No ulterior motive. As I stated, we have had excellent reviews on the product from our customers and we have had excellent reports from our time on the range with the FMK's. David at FMK has been nothing but the epitome of customer service. We also sell billet uppers and lowers; both the polymer and the billets have their place in the gun safe!

http://www.hamrickenterprises.com

It struck me as a little odd (and annoying) that your first post to the forum is an accusation that one of the members over-torqued his castle nut. Not to mention the last post on the subject was over 3 months ago. In the very first post, it was stated that he's made 15 or 16 lowers, including 8-9 with NFA polymer lowers, so I'd think he has it figured out by now. Maybe he did overdo it on this one, but I wouldn't assume that based on the facts presented. It rubbed me the wrong way...

If you are calling that thing on the Receiver Extension, it is not a buffer tube, a Castle Nut you or probably the one that failed have not figured it out and the fact that someone has performed a task repeatedly and it appears to work does not mean its right. The only difference is knowing the difference which most do not. I'm late on making a comment as I typically avoid these forums purely to avoid this type of discussion. In the case of FMK Receivers I've have yet to have any of the Four I obtained fail.