PDA

View Full Version : ar 308 lowers made from Billet process. thoughts


ar15student
10-24-2010, 8:04 PM
Hi what is a lower ar 308 made from billet? is this preffered over others? what are the other ones? what are the pros and cons? thanks

Kerplow
10-24-2010, 8:58 PM
it is machined from one solid piece of aluminium as opposed to a aluminum forging that is then finish machined. i think the main pro's are just looks really. they have an integrated trigger guard which is probably stronger and doesn't run the risk of damaging the lower while installing the trigger guard. IMO, either one is good.

Josh3239
10-24-2010, 9:00 PM
It is forged or billet. Billet looks better, but it typically more expensive and not as strong. To make up for the slight "weakness" they are usually built thicker, but really the lower is such a low stress part anyways that I think the added thickness is more for peace of mind.

C.G.
10-24-2010, 9:18 PM
In a simplified explanation there are three types of lowers: forged, billet and cast. Forged is the strongest and cast is the weakest.

Forged means that the metal is shaped by pressure, then machined and is the most dense; billet is CNCed from block of metal, is less dense then forged and may be heavier to make up thickness in weak areas and cast is pouring molten metal into a casting, it is least dense of the three.

Personally I prefer forged lowers and uppers although the AR-15 lowers do not see much stress; I would stay away from cast lowers.

Nathan Krynn
10-25-2010, 1:33 PM
The key here is .308. There are no forged .308. They are billet.

C.G.
10-25-2010, 8:02 PM
The key here is .308. There are no forged .308. They are billet.

Maybe true about DPMS style .308 lowers, but AR-10, Aero and Noveske N-6 AR-10 style .308 lowers are forged.

jamesob
10-26-2010, 5:32 PM
Old bushmaster an era 308 are forged as well.

bomb_on_bus
10-26-2010, 6:20 PM
billet allows for more options for designs etc. on the lower receiver. Most of the vendors out there that offer billet have all sorts of little bells and whistles that dont do anything for function other then look cool other than the flarred mag well.

ar15student
10-28-2010, 5:18 PM
Thanks it seems like there is nothing wrong with the billet. thank you.

Code7inOaktown
10-28-2010, 11:44 PM
Who makes cast AR receivers?

C.G.
10-29-2010, 1:52 AM
Who makes cast AR receivers?

Probably before your time, but FAB-10.

jamesob
10-29-2010, 6:25 AM
Who makes cast AR receivers?

oly arms made cast ones in the 80's

CHS
10-29-2010, 9:34 AM
The key here is .308. There are no forged .308. They are billet.

Armalite AR-10 (and Noveske and Aero-Precision) are forged.
RRA are forged.
Bushmaster BAR-10 are/were forged.

9-12
10-29-2010, 10:35 AM
The key here is .308. There are no forged .308. They are billet. Not true by any means. The best of the .308's are forged. They're the strongest and the lightest. The next best process is an extrusion, like DPMS. This is not a billet, but close. It's a cost effective method of manufaacturing something like a receiver, but not quite as strong as the AR or other forged receivers. Then there are the billet receivers which have zero advantage over the forged or even the extruded receivers except the "cool" factor.
Forged vs. billet isn't just a lower issue...the upppers are in the same catagory and are definitely a stressed part. Something to consider.

Joe788
10-29-2010, 11:24 AM
The next best process is an extrusion, like DPMS. This is not a billet, but close.

Ugh. A "billet" receiver is manufactured in the exact same manner as an "extrusion". The only difference is the shape the material is extruded into. In fact, a billet receiver machined from a cold finished bar will be "stronger" than a receiver made from a straight extrusion of the same material.

9-12
10-29-2010, 5:38 PM
Ugh. A "billet" receiver is manufactured in the exact same manner as an "extrusion". The only difference is the shape the material is extruded into. In fact, a billet receiver machined from a cold finished bar will be "stronger" than a receiver made from a straight extrusion of the same material.Ugh...not really, but OK, if you say so. In that sense, a forging can be considered a billet as well.
:sleeping:

Joe788
11-02-2010, 2:15 PM
Ugh...not really, but OK, if you say so. In that sense, a forging can be considered a billet as well.
:sleeping:

No. A forging has been forged. A "billet" receiver has been machined from an extruded bar, that may or may not have been cold finished. Saying the extrusion is "better" than a flat bar is utter rubbish.

captbilly
11-02-2010, 3:27 PM
There is no practical way to make a metal more dense by forging. You can definitely make the metal stronger than cast if it is forged properly. If done in just the right way a forging can align the crystal structure of the metal in the correct direction to handle the stresses, but simply forging does not necessarily aling the structure this way. A billet part can be every bit as strong as a forging, and may actually be stronger since a manufacturer can select from an extremely wide range of extruded or forged metal stock, but may have only a few choices of forgings. In addition a billet can made from a rolled forged bar, so a lower made from such stock would actually be a machined forging.

The only way to know if a particular manufacturer's upper or lower receiver is stronger than another would be to test it. Since most of us have no way to do the necessary tests, and they would be quite complex even if we did have the test equipment, we just have to go with what other people have used with success. I have heard of no issues with any lower breaking. About the only locations on a lower that are subject to normal wear are the trigger and hammer pin holes, safety holes, magazine release hole and the takedown pin holes. Aluminum is not a particularly good material for wear, due to low abrasion resistance, and I don't believe that forging help much in this regard. The way some people deal with the wear of the trigger pins is to install pins that either don't rotate or are tight enough that they don't move at all. If your upper and lower fit tightly then there should be little wear of the takedown pins, but if your upper moves every time you fire the rifle then the takedown pin holes will wear.

Josh3239
11-02-2010, 3:55 PM
Non-rotating pins rarely have anything to do with lower receiver wear. The top 2 reasons why people say they buy them is because they either look cool or because something is out of spec and the pins are walking. There are AR15s that have sit in military armorys that are 50 years old and have seen atleast one war that do not require non-rotating pins or o-rings on takedown pins. Lower receiver wear is largely non-existent. It is a very low stress part. Has anyone ever seen a lower receiver that has been shot enough to the point were it is out of spec? I have never seen nor heard of it.

BKTJ
11-02-2010, 4:14 PM
I have ones from CMMG, POF and Iron Ridge and they are all billet. The best finish of the 3 is POF with Iron Ridge a close second. In Texas I have both DPMS and Armalite. They are equal to the CMMG for finish, but I think both of those are forged. Plus neither is legal in Cal.
The CMMGs have tight mag wells, but take a regular 308 lower build kit. The POF is really slick and takes a regular AR15 lower kit. The only caveat is that the POF requires a filler bushing when using a DPMS upper. The POF hinge pins are undersize. There are others, but CMMG and POF have been around longer.

C.G.
11-02-2010, 5:34 PM
There is no practical way to make a metal more dense by forging. You can definitely make the metal stronger than cast if it is forged properly. If done in just the right way a forging can align the crystal structure of the metal in the correct direction to handle the stresses, but simply forging does not necessarily aling the structure this way. A billet part can be every bit as strong as a forging, and may actually be stronger since a manufacturer can select from an extremely wide range of extruded or forged metal stock, but may have only a few choices of forgings. In addition a billet can made from a rolled forged bar, so a lower made from such stock would actually be a machined forging.

The only way to know if a particular manufacturer's upper or lower receiver is stronger than another would be to test it. Since most of us have no way to do the necessary tests, and they would be quite complex even if we did have the test equipment, we just have to go with what other people have used with success. I have heard of no issues with any lower breaking. About the only locations on a lower that are subject to normal wear are the trigger and hammer pin holes, safety holes, magazine release hole and the takedown pin holes. Aluminum is not a particularly good material for wear, due to low abrasion resistance, and I don't believe that forging help much in this regard. The way some people deal with the wear of the trigger pins is to install pins that either don't rotate or are tight enough that they don't move at all. If your upper and lower fit tightly then there should be little wear of the takedown pins, but if your upper moves every time you fire the rifle then the takedown pin holes will wear.

I agree on some, but disagree on some. Give these a read:
http://www.forgingmagazine.com/zone/1190/news/71523/aluminum_forging_processes_an_overview
and
http://victorylibrary.com/mopar/billet-c.htm