The billet lowers do look nice, or at least different. but functionally are they any better than standard forged lower?

Billet lowers look nice but forged lowers work just as well.

No...

All non-cast lowers are created equal... The difference is appearance/finish, and the writing on the side....

There is no reason to spend over $100 on a lower, UNLESS you can't find one anywhere for under $100.

What about the differences in strength between forged and billet?

Functionally irrelevant. The lower is not a stressed component of an AR. As long as it is in spec and not cast, it's good to go.

I find WAY more advantages in a billet UPPER.

By "way more" I think you mean cost. And by advantages I think you mean looks cooler

Uh no -

The upper is where the magic happens.
This is where the proper thread alignment for the barrel and H/Gs happens.
This is where proper bolt/carrier alignment happens.
You want to squeeze accuracy? It ain't gonna happen in a fancy lower.



The only lower I've seen that impresses me with any significant advances is the KAC SR-15 E3 IWS
...and it's not billet.

and I would suspect that when using a heavy, long barrel one of the beefy billet uppers from Larue, VLTOR, and Alexander arms give an advatage in strength holding up that heavy barrel.

Vltor's uppers are forged now.

The lower is a stressed component. I have seen FCP holes wallow out and a extension area break off. Yes, they were cast but still suffered injuries from shooting. I see you did mention cast but that is irrelevant to stress. If there wasnt  stress then the Aramid receivers would be worth something.

I mean stressed as in bearing the loads associated with the rifle firing. Of course the lower is stressed - the whole rifle is stressed when you're using it. There is a threshold of strength below which you don't want your lower to fall - I suspect cast and CF lowers reside somewhere below that threshold. The original question was about forged vs billet, and both these tend to be of adequate strength.

Has anybody done any real testing on any of the "Billet/Machined Receivers" to determine if they are really any stronger than some of the Forged Receivers (given they are of the same design specifications)?

I ask because $#!@ equals $#!@ out. Meaning if you start with an average quality billet and machine it, it will not necessarily be any stronger than a good quality forging.

The quality of a "billet" can vary greatly, just remember every billet actually starts off life by being cast. If the raw materials and casting process are not managed properly, then the result will be a poor/low quality billet. Machine a poor quality billet, and you will get a poor quality finished product.

Quality and performance are not always synonymous with any particular manufacturing process, meaning you can have a poor cast, machined, or forged part. It all really comes down to the design and quality control level of the process from start to finish.

Also remember, the strongest billet in most cases will actually be one that has been through a multi-step casting and forging process. I would guess, most billets used in  the "Billet/Machined Receivers" start off as a standard cast billet.

Obviously some of the "Billet/Machined Receivers" can be stronger than the Forged Receivers because the design adds more material in the critical areas.

The science and actual performance levels do not always equal the sales pitch and hype on the street!

Food for thought,
"Capt Richardson"

Since the billet that used to mill "billet lower" were cast, then wouldn't it stand to reason that it's really no better than your cast lower? I'm talking pound for pound, with same spec, and not having additional thickness or strengthening beyond the Milspec.

So in that sense, forged lower would be stronger than billet lower, except that billet lower makes up for the difference by having additional strengthening.

So does anyone mill a billet that's forged? That'll probably yield the best receiver.

Forging is stronger as the grain follows the profile of the lower.. not that it really matters..

Not exactly,

The quality of a casting can vary greatly depending on a number of factors.

When you attempt to cast something like a Lower, the 2 big issues are:
- Getting the material to fill the mold evenly, with a complex mold like a Lower, it can be difficult to get the material to flow into the mold evenly and fill all areas consistently. Pouring/placing the material in the mold can easily result in trapped or entrained air which will result in varying thickness of the material.
- Getting the material to cool evenly and at a the desired rate. With material in a Lower Mold, thinner areas and areas closer to the outside of the mold will cool more quickly. The result is varying strength in the material, cooling at the wrong rate can make it brittle or weak.
This means if the casting is not done properly a Lower can be very prone to thin areas, and areas that are brittle or weak.


When you cast an Ingot or Billet it is easier to control the issues because you are pouring the material into a simple / open mold. As such you can get a more consistent and complete filling of the mold and a more consistent cooling rate.

Hopefully that makes sense!
"Capt Richardson"

Machining from billet is time consuming and expensive to do.  However, its startup costs are considerably less than forging.  

A forged receiver is going to be stronger than almost any possible billet receiver.  (As has been covered here most billet is a casting, a simple casting but still a casting)  As has also been covered the strength in forging comes from molecular grain changes that occur durring this process.  

Look at any advertisements for billet uppers or lowers and it says something like "stronger than cast, more pricise than forged".  

Realistically, the most important factor in any quality upper or lower is dimensional accuracy.  

Don

Another couple of thooughts:

Often a part is engineered specifically to be forged or cast.  Sturm Ruger makes high quality firearms almost exclusively from cast parts.  In fact they are considered to be such experts on very high qualty castings that many aerospace vendors subcontract out complex casting work to Ruger.

So while their firearms are strong and accurate, they are designed to be cast.  You can see this in the somewhat bulky appearance of their revolvers, in comparison to a forged S&W.

So one interesting point is that the original AR's were forged.  So to take the same shape with no dimensional changes and expect it to work just as well as a casting may be unrealistic.

But then again.  A really well done casting would probably last a lifetime.  Noone can say that a casting that is machined, heat treated, stress relieved  and then final machined to precise dimensions would not do an excellent job.  

But a casting of this quality would be as expensive as a forging.  And since most of the cast receivers are done that way to save costs , its safe to say that such a complex process was not used to make them.  

So really a cast receiver COULD be just as good as a forged, but realistically, probably isnt.  

Don