Billet AR receivers worth it?

[Kingjamez]

How can you have an opinion on whether or not something is lighter? It either is or isn't. Either way it's way to minimal to matter unless somewhere out there someone is making billet receivers specifically to be lighter and then at what sacrifice?

BTW in my post I was in no way trying to be a smart ass, but I had never heard of billet receiver being lighter. If indeed it is then I would be interested in knowing which manufacturer is making them.

+1 It seems like he is talking about a mil spec lower. In that case, unless there is a difference in alloy a milled should be pretty durn close to a forged in weight. Even if the alloy was different (6061 vs. 7075) the difference would be in literally thousandths of a pound.

As to a lighter milled receiver. I've seen a few skeletenized billet lowers that had a decent weight reduction. I'm currently building a plastic lower out of Delrin which weighs just over half what aluminum does per cubic inch. However, lowers don't weight much and even if you dropped the weight of the lower in half, it would make a large difference in the weight of the rifle.


-Jim

 

[kalister1]

I don't get the thing about billet. It was cast in a foundry, machined and now it's a gun. A forging makes a difference, but all Aluminum is cast somewhere. You can't just dig up a piece and machine it.

 

[platekiller]

KingJamez- are you making your own lower? if not who makes it?

Anyone ever use one of the polomer lowers? What make and how are they?

Platekiller

 

[Kingjamez]

KingJamez- are you making your own lower? if not who makes it?

Yes see signature, but replace the aluminum block with Delrin.

-Jim

 

[jason.krywicki]

Weight is a measurable quantity. Post numbers of both types (billet vs. forged) and then we can compare.

Regarding machining a lower out of Delrin - be careful. Delrin that is not glass filled will cold flow on you. What this means is that, under the repetitive shock loading from gun fire, you'll eventually start to egg out holes or deform other critical features. Eventually might not be very long either.

Jason

 

[Kingjamez]

Regarding machining a lower out of Delrin - be careful. Delrin that is not glass filled will cold flow on you. What this means is that, under the repetitive shock loading from gun fire, you'll eventually start to egg out holes or deform other critical features. Eventually might not be very long either.

Jason

Keeping in mind thread drift, I'll answer this briefly.

It's an experiment only, I also make them out of aluminum but when trying out new designs, machining is much easier in plastic. It takes me about 4 hours and $25.00 to take a block of delrin to a working lower. The forces on an AR lower are surprisingly low. I have reinforced the buffer tube area and the FCG group pins will get flanged ball bearings (or bushings) to ride in. That should eliminate egging in the trigger pin or hammer pin. It may not last long, but I'm going to find out how long it will last.

-Jim

 

[vin]

Thanks for all the input guys. I think I'll save the few bucks on the receivers and go forged and put that extra money into parts that will affect how it shoots. Like a higher quality barrel.

Delrin huh? Interesting. Im curious how that turns out. I haven't heard great things about other plastic based receivers, hope you have better luck.