How strong is HDPE?

[Captain Evilstomper]

probably better than Hesse/Vulcan

[damon1272]

kind of a cool exercise. Kind of pointless. HDPE is very strong. Look how much you can put in your average 5 gallon bucket. HDPE is used for live line replacement and bursting. It is welded in the field and the welds are stronger than the pipe itself. I would have rather seen something out of a different material as HDPE is dense. Now I would really be impressed if he did the upper with it.

[NSR500]

Depending on the cost, HDPE could be a good material to CNC prototypes with, right?
For example, if you'd like to make an AR15 lower with different features like, trigger guard shapes, fencing, etc...
I'd hate to be buying up 7075 aluminum blocks just to experiment.

[bohoki]

id love to have one made of polypropylene or teflon block

polypropylene is the plastic they use when they make a box with the hinge that is made by being thin and just bent like a cheap tacklebox

and teflon can take like 700 degrees

[bombadillo]

I pulled 90' of HDPE through an existing sewer line and it had 4 seams in it. We bonded it together and pulled it through 3 90* corners under a neighbors house with a xx ton hydraulic jack. It is incredibly strong.

[JagerTroop]

id love to have one made of polypropylene or teflon block...
...and teflon can take like 700 degrees

Yeah, but Teflon is kinda soft.

HDPE (fyi; HDPE = Spectra, Dyneema, or Tensylon) would be neat. A bulletproof gun

[NSR500]

What is the Compression like with HDPE?
Can it support a lot of weight?

I am thinking of using some to protect AR15 barrels when I put them in a vise. Also thinking of melting it an putting it inside the upper receiver to support it from the inside when I put barrels on.
DPMS makes stuff like that, but I like the idea of making things myself as long as it is cost effective.

[SKG19]

Yeah, but Teflon is kinda soft.

HDPE (fyi; HDPE = Spectra, Dyneema, or Tensylon) would be neat. A bulletproof gun

Nope sorry...UHMWPE = Spectra, Dyneema, etc...
UHMWPE and HDPE are not the same.

[AaronHorrocks]

id love to have one made of polypropylene or teflon block

polypropylene is the plastic they use when they make a box with the hinge that is made by being thin and just bent like a cheap tacklebox

and teflon can take like 700 degrees

Telfon is too soft. You'll want to look into UHMW.

[bplvr]

Telfon is too soft. You'll want to look into UHMW.

Teflon will only take 700 F ONE time .That is how you bond it to the aluminum fry pan. After that it will be destroyed at 400 F.
A better choice would be a silicone whisker reinforced 7075 T6.

[AJAX22]

Your receiver doesn't get that hot.

The AR receiver sees so little stress.

I'd only worry about the extension and what would happen with a KB.

I'd be willing to bet that HDPE would be safer than aluminum in the event of a KB... it tends to bend and then fracture in chunks not shards, most of the potential hazard to the operator in the event of a KB is from the material of the gun being acting as shrapnel.

I'd buy one...

[JagerTroop]

Nope sorry...UHMWPE = Spectra, Dyneema, etc...
UHMWPE and HDPE are not the same.

Sh!+, you're right. I should know this. That being said, why not just make it out of UHMWPE?

[goathead]

that was cool

[rayra]

To the poster that said it's a pointless exercise - hell no. The guy just went thru the exercise of fabricating an in-spec lower for an AR. And did it for cheap and with little or no wear on his manufacturing equipment.


And for those of you considering a hardy plastic, take a look at Delrin. Certainly sturdy and stable enough for assembly jigs.

[Bug Splat]

THAT IS AWESOME!

Someone should send these pictures to our congress people with a note saying it can pass through metal detectors then watch them crap their pants and run around screaming.

I think a plastic lower is a great idea but I would use an aluminum insert for the tube, lugs and LPK then just mold the rest. Lowers could be pumped out in seconds at the MFG.