AR lowers, what’s the diff?

[Pfoneman]

I don’t see how. There is a reason the the military has specified forged receivers on every military rifle from the 1903 Springfield to the M16. You get a true grain flow in a forging that aids in the overall strength. When you mill a piece of bar stock (same as making a billet receiver), you cut those grain flows.
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I do know this. I’ve put together more performance engines than I care to remember. I’ve seen engines built personally that have any where from 150 to 3000 hp. The ones that stay together longer ALL had forged internals. No exceptions. Reason? Stronger. Why? Exactly the reason cmshoot said. Casting disrupts the molecular makeup of a certain metals and billeting from stock cuts through the molecular makeup. Forging keeps them aligned thus keeping the strength. If you buy a billet piece for a car build it is purely for aesthetics and not because of any undue pressure being put on that part.

 

[CTS Tactical]

I do know this. I’ve put together more performance engines than I care to remember. I’ve seen engines built personally that have any where from 150 to 3000 hp. The ones that stay together longer ALL had forged internals. No exceptions. Reason? Stronger. Why? Exactly the reason cmshoot said. Casting disrupts the molecular makeup of a certain metals and billeting from stock cuts through the molecular makeup. Forging keeps them aligned thus keeping the strength. If you buy a billet piece for a car build it is purely for aesthetics and not because of any undue pressure being put on that part.

Same is true of billet receivers. Purely aesthetics. If they claim it is stronger than forged then it is just what I said earlier. False advertising. Marketing BS.

 

[GunNfun]

Only difference I’ve noticed: wall thickness of lower. A larue upper will not fit in a noveske lower. But it will fit a spikes or Anderson lower. The internal dimension is tighter on the higher end lowers and the rear lug on the higher end upper is thicker. The purpose is to limit movement through tighter tolerance making for greatWe accuracy. I didn’t notice a difference. Stay in the same pricing level and everything should fit.

 

[NewLeaf]

Learn something every day.

 

[Winterborne]

Assembly can be another point.
Barrel to receiver fit is better tight than loose.

When I use to build uppers for extreme accuracy the barrel fit had to be tapped in with a mallet...and green lock tight was used.
The upper receiver was considered replaceable if a tear down was called for.

A special order forged billet was milled into an upper for AR15's that used a bigger cartridge.

For years the M1a dominated service rifle competitions but as the Army Marksman Ship unit proved the AR platform could be made to shoot competitively.