Recievers of different assault rifles.

[Amish]

I was doing some research into the SIG 550 and noticed that it's recievers are stamped. I thought they were milled from what I thought were lightening cuts on the sides like on milled AK's. Nope. Then I started to look at other assault rifles to see what they were built on so this is what I found:

SIG 550: Stamped upper and lower.

FNC: Stamped upper, aluminum alloy lower.

Beretta AR-70/90: Stamped upper and lower

AR-180B: Stamped upper, polymer lower

L85: Stamped

Valmet: Milled and Stamped versions. Current version is milled.

Galil: Milled

AK: Milled and stamped versions

Daewoo K2: Aluminum alloy upper and lower.

AR-15: Aluminum alloy upper and lower.

 

[jacketch]

AR-15: Aluminum alloy upper and lower.

The AR-15 has both forged and cast receivers available.

Alloy is a description of the metal(s) used.

Forged, cast and stamped are fabrication methods.


A number of longarms besides the AR180B (including the G36) now have polymer receiver parts .

 

[Badger Arms]

There is also another method of fabrication only used on the Bushmaster Imbus, IIRC. That's Extruded. Extrusioin is a linear forging method most commonly seen on window frames. It's fairly cheap and very effective. It essentially produces an endless lenght of aluminum or other metal with the same cross-section.

 

[Fudgie Ghost]

Generally speaking, which yields a stronger piece, forged or cast?

 

[jacketch]

All other things being equal the forging will be better (but more expensive). That does not mean that castings won't make an excellent receiver.

 

[Badger Arms]

Strength is a relative term. For a receiver, you generally want surface hardness and internal elasticity to prevent the piece from cracking. Cast receivers tend to give the most consistent hardness throughout, however forging arranges the grain strucutre to the advantage of surface hardness. The difference is really more aesthetic when you apply it to firearm receivers. Milling from a billet will produce stress concentrations that you don't get from casting but you do get from forging. All things being equal, a forged part looks better, a milled part will be of a closer tolerance, and a cast part will be cheaper. Again, the differences are mostly those of looks when it comes to making assault rifles.

 

[artherd]

JP Rifles also makes a billett milled aluminum AR reciver (both lower and uppers) They look absolutely amazing.

 

[Zak Smith]

The JP CTR "AR" receiver:

Both the upper and lower are machined from blocks of 7075 Al.

-z

 

[cookie]

The FNC may have a stamped upper and alloy lower, but it feels solid as a tank.

 

[AZ Jeff]

There has been a trend in modern small arms to lessen the cost of manufacture. This was really launched as a concept by the Germans in WWII, when stampings began to supplant traditional machined and forged parts.

Stamping technology, and the steel alloys to support this technology, has come a long way in the past 50 years, particularly in the past 20 years.

A stamped steel rifle receiver is not necessarily inferior to a forged and milled version. It IS, however, typically cheaper & faster to produce.