Been looking at some uppers w/lugged sights.

How can I tell if they are cast or forged??

One has a front sight with a "D" , "99" , and a D in a circle on the "crossbar".

Thanks for any help.

Mike

The best way I use, and this worked for IDing forged, and cast crank shafts for BB Chevys.

Look at the front sight in front of the muzzle. You will see a line that runs up the site tower from top to bottom. [b]Cast[/b] is a thin, raised and, pointed line. [b]Forged[/b] is wider and smooth. Looks like it was ground down.

So.. Thin and pointed = Cast
    Wide and flatened = Forged.
Edit: My forged line is >1/8 inch wide on my Colt.

Hope this helps.

Spooge Out!

Are you trying to tell if hte upper or the front sight is cast / forged?

As mentioned above, a cast front sight looks better, crisper than a forged one.

As far as the upper goes, I am not sure there are any cast ones anymore...

Thanks.  It is forged.  Glad.

Any material differences in receivers??

In general, you cannot change the material a part is made with and not change the design of the part. Ever wondered why Ruger pistols are so blocky? They're cast. You can't make cast AR parts using the same design without compromising strength. For a cast part to be a strong as a forged one there has to be more material, particularly on corners and radii.

Here's some pics of forged FSBs and uppers illustrating the forging "seam". Some companies are going out of their way to remove these seams for various reasons.


The seam is visible on top of the upper beneath the carry handle.


A different view of the same area.


Corresponding seam on the bottom of the carry handle. For any that have wondered, the small raised line on the cam pin clearance cut (rectangular "box" forward and above the bolt catch) is an index line for the parts. All measurements on the upper are based off of it in some manner.


Vertical line through center of FSB is forging seam.

Three dead giveaways of forged front sights


Note rounded edges of FSB. Cast FSBs are blocky and squared on the edges. Note also the use of correct taper pins not roll pins or dowel pins and rivet retaining front sling swivel.


"UP" stamped into the steel and milled protective wings. Note that the wings appear flatter on the inside than on the outside. Note also forging seam on the rear of FSB along centerline of part.


Milled bayonet lug. Note squared lines and clean surfaces.