Pourable AR-15 lowers

[turbo89]

Yeah, probably.
If you have a vacuum pump and chamber you can make some really high quality stuff. Pour it. Put it under vacuum and all the voids and bubbles come out, then release the vacuum and atmospheric pressure pushes it into all the little corners.

I need to unsubscribe from this thread. I have a built-in need to make things, but I already have too many hobbies. I'm getting a very strong itch to get into this casting stuff. I need to nip that in the bud before it takes me over.

This X2! Cycling the vacuum on and off a few times will really help get the air out.

Also - Fiberglass tape is great at sucking in resin and will add significant stiffness to the part. I bet hockey tape would work pretty good too because of it's lacing content.

This definitely has potential to yield strong parts... but the process is important.

 

[namedpipes]

The various (non-reinforced) poly AR lower manufacturers sell the things - so there must be room for them in the cited regulation.

Or do they include some sort of detectable material in the plastic??

Honestly I'm not sure. I was being a wiseacre.

However, the act requires the firearm be detectable. Metal reinforcements would do that.

It seems if the lower receiver is considered a firearm then that is the part that needs to be. Perhaps they figure a bolt or the upper will be sufficient?

 

[Boris]

The various (non-reinforced) poly AR lower manufacturers sell the things - so there must be room for them in the cited regulation.

Or do they include some sort of detectable material in the plastic??

They all do. That law expired year or two back and was extended, because .gov got to keep priorities straight.

 

[Kevin_NH]

Honestly I'm not sure. I was being a wiseacre. However, the act requires the firearm be detectable. Metal reinforcements would do that. It seems if the lower receiver is considered a firearm then that is the part that needs to be. Perhaps they figure a bolt or the upper will be sufficient?

The "Undetectable Firearms Act of 1988" (18 U.S.C. § 922(p) requires it to look like a gun on X-ray and also be no less detectable than a test item built with 3.7 oz (105 g) of steel. For the purposes of Undetectable Firearms Act compliance, the trigger group internals count.

Worst case, just use a drop-in trigger module, e.g. Timney.

Or do they include some sort of detectable material in the plastic??

barium sulfate works as an X-ray contrast additive.

 

[browncoat]

The plastic has to show up on an xray and look basically the same on the xray as it does visually. It doesn't need to contain metal as long as the other parts have enough metal to set off detectors

 

[Boris]

The plastic has to show up on an xray and look basically the same on the xray as it does visually. It doesn't need to contain metal as long as the other parts have enough metal to set off detectors

but not in metal detector, hence the requirement about min metal piece.

 

[browncoat]

but not in metal detector, hence the requirement about min metal piece.

The firearm assembled has to show in metal detector. Firearm components must show in xray. Law says specifically that receiver is not firearm for purpose of that subsection

 

[bigblue]

The firearm assembled has to show in metal detector. Firearm components must show in xray. Law says specifically that receiver is not firearm for purpose of that subsection

So by that logic the receiver must show on xray & when the bbl is added it will trigger a metal detector. Thus the barium additive.

 

[browncoat]

So by that logic the receiver must show on xray & when the bbl is added it will trigger a metal detector. Thus the barium additive.

Yes. I was responding to the idea in namedpipes post where he thought the receiver needed to have metal reinforcements. It only needs to show up on xray, if the plastic does that without additives it is fine to be just plastic

 

[Almostelmo]

The "Undetectable Firearms Act of 1988" (18 U.S.C. § 922(p) requires it to look like a gun on X-ray and also be no less detectable than a test item built with 3.7 oz (105 g) of steel.

I know this question is way off topic, but I'm curious how a slam gun "looks like a gun" under this requirement. Sure, it's two lengths of steel pipe, but it doesn't look like a gun at all.

 

[Boris]

I know this question is way off topic, but I'm curious how a slam gun "looks like a gun" under this requirement. Sure, it's two lengths of steel pipe, but it doesn't look like a gun at all.

I think that they explicitly were aiming to control things that look like something else, i.e. pen or umbrella guns