Strength of Plastic Receivers?

[xd007]

Hello-

I am new to the forum and have a simple question...

How strong/durable are the "plastic" receivers of rifles such as the HK G36 and the FN FS2000 in comparison to the machined aluminum of the AR-type rifles?

It seems that the AR-type aluminum receivers would be far more durable, but I cannot find any imformation to support this theory, and would appreciate your feedback.

Thanks so much!

 

[swingset]

I hate to say "it depends", but it depends.

Polymer receivers can be, if made right, as strong if not more durable than aluminum. Conversely, they can be weaker depending on the design and the material the receiver is made out of.
Some polymers are stronger than aluminum as far as abrasion, cracking or impacts. Polymer tends to "give" instead of cracking, so in some cases they are preferable in case of explosion or external damage....but again, it depends on the execution.

As for a test you can do yourself, drop an aluminum receiver in the gravel about 100 times, then do the same thing with a polymer one. Wipe both with some CLP and see which looks worse.

 

[xd007]

Thank you for the quick and detailed response! Is that to say the 2 materials are "just about" equal?

Thanks!

 

[swingset]

Both have strengths and weaknesses. It all depends on the design of the gun and the material quality.

The AUG, Glock, G36, etc. are all proven and reliable actions built on polymer. However, some guns just aren't built to accomodate polymer in the design. Some designs are built around the rigidity of a solid steel receiver.

 

[xd007]

Thanks again, much appreciated!

 

[mrmeval]

Cavalry Arms makes an entire polymer lower for the AR, it includes a molded in buttstock. It's light and functions fine but they did include some differences from a metal lower. I have heard it is not a good idea to 'flip' it open as it can damage the front of the lower so both pins are removed for cleaning. It makes a damn light gun.

 

[cuervo]

As swingset mentioned, the design of the gun really comes into play, and how the polymer is used in the design. I haven't looked at rifles as much, but if you look at most pistols, they all have metal sliding on metal. (Off hand, the Ruger P95 is the only polymer-framed pistol I can think of that has the slide directly on the polymer.)

The polymer portion of the frame is used to form the grips and the slide rails are set into the polymer, either molded in or pinned.

In some pistols, such as Kel-Tecs, the polymer frame does little more than just hold parts together. The actual (legal) frame is a small piece of aluminum and the polymer forms everything else around it. The stressed parts are all steel.

The AR makes a good platform for a polymer gun because the upper is doing all the work--the lower receives relatively little stress. This is why there are .50cal rifles built on standard AR lower.

hth

 

[MechAg94]

I believe my Kahr P9 has metal on polymer with the slide.

 

[10-Ring]

Poly guns can be VERY VERY durable. It would depend mostly one the type of poly used and the design of the firearm. I think tho that w/ what is riding on each new design a company intro's, they would have gone through all the proper r & d to make sure their firearm is well made