M&P15 Sport : forged or cast upper / lower ?

[PAPS94]

Hello from France !
I'm going to buy an M&P15 Sport rifle but someone said to me that S&W M&P upper or lower are cast and not forged...
Is it true or not ?
It would be very surprising...!
Are there differences between Sport model and the others about production process ? (except dust cover, FA and trigger guard)
Are S&W receivers made in house ?
What are the marks on the upper or lower ?
Sorry for my english !
Thanks !

 

[BillyMagg]

Hello from France !
I'm going to buy an M&P15 Sport rifle but someone said to me that S&W M&P upper or lower are cast and not forged...
Is it true or not ?
It would be very surprising...!
Are there differences between Sport model and the others about production process ? (except dust cover, FA and trigger guard)
Are S&W receivers made in house ?
What are the marks on the upper or lower ?
Sorry for my english !
Thanks !

Very good question, my Rock River is all forged, and I would hazard a guess that the Smith Sport is as well, although there are some cheaper ARs coming on. I found out very recently that my mid 90s Winchester Classic Super Grade had a cast receiver, the barrel and bolt body were forged and the receiver was gorgeous on top, but a fellow told me it was cast an he was right, I was quite disgusted and traded it for a browning Safari. LOL
Most of the ARs are finish machined in house from forgings made by a limited number of forgers, sometimes one company will use the blanks of several forgers, but do the final machining in house, so it is sometimes difficult to say, I will attempt to do a little research, but hopefully someone more knowledgeable will be on here shortly. Billy

 

[rojodiablo]

The vast majority are castings. Like as in, 90% plus are cast. The casting process is simple and gives good results.
Maybe more important is whether the uppr and lower are 6061 or 7073 alum. This matters in 2 ways; out of the box, 7073 is stiffer, and has a higher overall strength. But, it can be more brittle. Should you ever crack off a chunk of a 7000 series alloy rifle, that part is done for. 7000 series aluminum do not accept welding without cracking. So, in many cases, MFG like the 7000 series for 2 reasons: 1. Max strength. #2. They do not like liability issues. If a person wants to modify their lower or upper, with a 7000 alloy, they know it will either be machined, drilled, or glued. If the lower/ upper were 6061; they could be modified and grafted to other things, and welded. Ther welds on castings can be fragile, so this is a simple way out- avoid welding issues by using 7000 series and it's done.
For mods like belt feed, custom magazine wells, etc. it requires welding, so some MFG make 6061 parts for just this purpose.

The cast lowers and uppers are just fine.

 

[PAPS94]

The vast majority are castings. Like as in, 90% plus are cast.

You're atlking about only S&W M&P or for all the AR's ? (DPMS, Stag, Bushmaster etc...)
It's surprising, to me I thought all uppers and lowers were forged, because we can see the forged marks like A or F etc... (Harvey, Cerro forge...)

S&W customer's service sent me an email to answer my question about this :

""" Dear Customer,

The upper and lower are both forged parts. Unfortunately i do not have the class or level of finish on the guns. This is a mil-spec rifle.

If further assistance is required please reply accordingly.

Sincerely,

Miguel """

So upper and lower of M&P rifles are forged and not cast.

I often read in spec descriptions that the receivers are made by 7075 T6 aluminium ?

Sorry for my english !!

 

[MichiganScott]

I found out very recently that my mid 90s Winchester Classic Super Grade had a cast receiver, the barrel and bolt body were forged and the receiver was gorgeous on top, but a fellow told me it was cast an he was right, I was quite disgusted and traded it for a browning Safari. LOL

Billy, I hope you posted this tongue in cheek because if you didn't, you are truly misinformed.

 

[BillyMagg]

Billy, I hope you posted this tongue in cheek because if you didn't, you are truly misinformed.

Well I initially was exactly where you are, but the one of the Mauser Central gurus informed me that I was incorrect, after pulling the receiver from the stock, I am rather certain it was indeed a casting as are most of the post 64 model 70s.... the North Carolina guns are indeed forged, so if I am misinformed I apologize. Billy

 

[BillyMagg]

You're atlking about only S&W M&P or for all the AR's ? (DPMS, Stag, Bushmaster etc...)
It's surprising, to me I thought all uppers and lowers were forged, because we can see the forged marks like A or F etc... (Harvey, Cerro forge...)

S&W customer's service sent me an email to answer my question about this :

""" Dear Customer,

The upper and lower are both forged parts. Unfortunately i do not have the class or level of finish on the guns. This is a mil-spec rifle.

If further assistance is required please reply accordingly.

Sincerely,

Miguel """

So upper and lower of M&P rifles are forged and not cast.

I often read in spec descriptions that the receivers are made by 7075 T6 aluminium ?

Sorry for my english !!

Actually I believe rojo is error, the Smith uppers and lowers are indeed forged for the M&P as are 90% of most ARs made in the US. I am rather certain that Ruger uses castings, possibly several other of the "new manufacturers of ARs", but most of the traditionals, Colt, Rock River, S&W, Daniel Defense, Spikes,and go on down the list use forgings. Now the latest cheap Colt that is in direct competition with the S&W Sport may in fact be cast????? rojo is right about welding and both 6061 and 7075 are the major alloys used to forge both uppers and lowers. I am not an authority, but I much prefer a forged part to a cast part any day, and yes I do know the difference, I am after all a Hillbilly, and I have worked on automobiles and aircraft professionally or at least drew pay to do same. Billy Magg

 

[MichiganScott]

Billy,

Go to The American Rifleman dot org and look for an article titled "The Model 70 Story: A Classic Advanced" written by Pete Dickey in 1980. I prefer to believe a peer reviewed article as opposed to an Internet guru.

The following is a quote from that article.

"The external form of the receiver was not changed, though it was no longer milled form nickel-steel bar stock but forged from chrome-molybdenum steel. Again no one complained.
The bolt body was machined from the same type steel as the receiver—with the familiar dual front locking lugs—and its handle, an investment casting, was securely pressed and brazed in place. There is nothing substandard in this arrangement."

 

[BillyMagg]

Billy,

Go to The American Rifleman dot org and look for an article titled "The Model 70 Story: A Classic Advanced" written by Pete Dickey in 1980. I prefer to believe a peer reviewed article as opposed to an Internet guru.

The following is a quote from that article.

"The external form of the receiver was not changed, though it was no longer milled form nickel-steel bar stock but forged from chrome-molybdenum steel. Again no one complained.
The bolt body was machined from the same type steel as the receiver—with the familiar dual front locking lugs—and its handle, an investment casting, was securely pressed and brazed in place. There is nothing substandard in this arrangement."

I stand by my own observations Scott, the poster was the gumsmith @ Mauser Central. The article that you are referencing was written 15 years before the Classic Supergrade with the pre-64 style action was reintroduced as a "Winchester". I waited nearly 6 months for the 30-06 to take its turn on the line, after pulling my receiver from the stock, I observed very apparent casting voids below the wood line, as I said the top of the receiver was very nicely finished and blued, if you find evidence to the contrary from an article written about the Classic, I will most certainly issue a retraction and another apology. I am quite certain that Winchester offered the model 94 with a cast receiver post 64, after lots of negative press they returned to a forged receiver for the 94, and now for the Southern Model 70 produced in the Carolina's. Billy

The author of your article is quoting Stuart Otteson's "The Bolt Action", which is written about the 1964, not 1994 model 70, I think you would agree that an article written 30 years prior to the Classic Supergrades reintroduction is NOT an authoritative source for determining the latter rifles provenance. However, if you find a specific source stating the Classic Supergrade is forged I will gladly retract my statement???? If however you are unable to substantiate your statement within a reasonable time, I think you should consider retracting yours as well. Billy Magg

 

[peteflstc]

I don't believe that any AR receivers are cast. They are either forged or billet. The ones that are forged are stamped into shape from a single piece of aluminum and then machined. Billet receivers as well are made from a solid piece of billet aluminum which is not stamped into shape but instead completely machined into shape on a CNC machine allowing for much sharper angles and customization than on a forged receiver. I, for one, prefer a forged receiver. Billet are nice looking, but mil spec is forged. I'll stick with that.

 

[cyphertext]

Pete, you joined a year ago, made your first post today, and it is in a thread that is a year old...

Welcome to the forum!

 

[jimbo728]

S&W MP 15 lowers are made in house.
Jim

 

[cyphertext]

S&W MP 15 lowers are made in house.
Jim

I'm not sure that you can say that with 100% authority. A couple of years ago we all saw the video where the S&W marketing guy claimed that S&W made the receivers in-house. Then we started noticing that some of us had Anchor Harvey forge marks on our uppers, and others did not. It became apparent that S&W wasn't doing them all in house.

 

[jimbo728]

You have a good point. When I researched the Sport in 2011 the info did come from S&W reps involved in torture testing the M&P 15 Sport. This came during the discussion regarding the trigger guard changes adopted for that rifle. It`s possible due to high demand Anchor Harvey got a piece of the action. It is probably fair to say the raw forgings came from Anchor Harvey and S&W finished them off in house but you are right, I can`t say that with 100% certainty. But I do believe that is true. As far as I know Anchor Harvey Forge does not make uppers or lowers but they are a forging vendor. Traceability , as required in all ISO manufacturing environments, is probably why you see the markings you described.
Jim

 

[cyphertext]

It`s possible due to high demand Anchor Harvey got a piece of the action. It is probably fair to say the raw forgings came from Anchor Harvey and S&W finished them off in house

I think this is exactly what happened. The guys with the early Sports did not have any markings, but some of the guys with the version that came with the rear Magpul sight noticed the forge markings.

We have learned that nothing seems absolute with S&W, no matter what marketing tells us.

 

[bhayles]

We have learned that nothing seems absolute with S&W, no matter what marketing tells us.

Ummm...not exactly. It is ABSOLUTELY true that I am happy as a clam with my S&W MP15 Sport.

Absolutely!

 

[tenx100s]

Forged AR15 Uppers and Lowers

I own a tool and die machine shop doing work for several OEM companies including aerospace. Most of our work is in prototyping and short component builds for specialized machines.
One of my customers is an aluminum casting house and I can say with a great level of certainty that if a gun builder states that he is using either 6061 or 7075 he is NOT using a casting. According to my customer who does their own casting, there are entirely different alloys for casting than what we like to refer to as aircraft aluminum. That vast majority of aluminum prototype parts we make for our aerospace customer are made from either 7075 (some 7050) rather than any 6000 series aluminum. There is NO aluminum casting alloy with the tensile strength or wear resistance of even the 6000 series materials. To get into that a designer would have to look at Zinc alloys.
Having said all that I would say that while I would willing accept a 17-4 PH Stainless Steel casting for a Freedom Arms Model 83 or a Ruger Redlabel I would NOT consider an aluminum casting for an AR15 that I intended to be a long term shooting. I also seriously doubt even experts at casting like Ruger would use them in their AR15 Rifles.
One last thing. I have a M&P 15 from the Performance Center and there are NO ejection pin marks on either its upper or lower. This is the rifle that I reach for when I want to shoot an AR15. I has a good trigger, great barrel and shoots well enough to get loaded in the truck for prairie dog hunting.

 

[EdP1946]

In general terms, aluminum alloys specific to casting contain a small amount of silicon. While this is good for some mechanical properties, it eliminates the possibility of using anodic finishes as the results are usually splotchy. Not what you would want on a quality firearm.

 

[rojodiablo]

Aaarrrgggh; to set the record straight; I MIS-SPOKE when I said a casting. The parts are in general a forging, as has been repeated. (Not sure how I wound up there, other than I was doing some work on casting parts and computer work, and reading here all at the same time.)

To anyone who feels that an aluminum casting would not be 'strong' enough, or wear resistant enough..........

From my years and YEARS of welding on all types of alloys, and machining them countless times as well- Aluminum is a material which absolutely LOVES to be used in castings, and in castings of high strength, and high stress. A short list of aluminum parts in life which most certainly ARE CAST: Engine blocks, from Ferrari sports cars to their F1 cars. Add to this list ALL aluminum motorcycle engines, many of which are structural in nature holding chassis members on them like swingarms, etc. Many gun parts are cast. Transmission housings for the mighty Allison transmissions used behind the Duramax diesel, as well as..... EVERY trans housing behind every other truck engine is made of cast aluminum. Many motorcycle frames are using steering heads which are indeed....... castings. And I mean 170hp sportbikes, to Supercross dirt bikes which routinely get jumped over 50 feet.
So YES- castings can be made 'strong enough'. casting materials DO differ in compounds simply because it is run in molten and then hardens as it cools, which will eliminate or change properties vs. alloys which might be starting life as a billet, and being either machined, extruded, or compressed (forged). But to be fair......all metals begin life as a casting. None are dug out of the ground whole. They are all smelted and refined, and then poured in a billet block of some kind, and worked from there. Some are reconstituted and materials added/ infused in a new casting. The rest are worked in other manners.

The most common grade of aluminum which does not take anodizing is 4043 filler. Most aluminum alloys take color anodizing, and hard anodizing like a duck to water.

 

[rojodiablo]

Here's a little brain-pain to go with your dinner tonight; read at your own risk!!!

Actually, good insight in a thread I was reading when I made my first incorrect post. This is only an excerpt- there was a LOT more, and some talk of how some 7075 has had positive results. (FEW AND FAR BETWEEN).

So, in a few too many words...: It isn't 'cast 7075.' This alloy as-cast has a terrible microstructure & I guesstimate the mechanical properties as about YS 25 ksi, TS 30 ksi, notched Charpy 1.5 ft-lb, and fatigue strength maybe 5 ksi at 5 x 108 cycles in R. R. Moore type test of smooth specimens. Criminal if such material flies (except as cargo)! Note: Try searching MatWeb by composition for a similar Al casting alloy – you won't find one. Maybe looks like a casting due to shot peening. Follow the advice above & track down the actual specifications.

7075 solidifies over the range 635 to 477 oC, with lots of segregation between higher melting intermetallics and a low temperature eutectic. Ingot intermetallics (DC cast, ~16oC/sec) are (Fe,Cr)Al3, (Fe,Cr)3SiAl12, Mg2Si, Mg(Zn2,AlCu) and CrAl7. It cannot be completely homogenized by heat treatment – significant hot working is required to break up and distribute the intermetallics. Also, Fe does not diffuse to any significant extent in the Al matrix below 400 oC, and Mn and Cr only above 500-550 oC.
--- Refs: various Metals Handbooks (phase diagrams, metallography & non-ferrous alloys), Aluminum Vol. I (1967), and Aluminum: Technology, Application and Environment, 6th Edn. (1998).

To avoid the casting microstructural problems, alternative methods include powder metallurgy using rapidly solidified powder, and more recently, thixotropic casting (stir casting) and spray casting. Note that in the article referenced by prost above, squeeze casting didn't solve the segregation problem (nor would HIP).

A few interesting articles on 7075 production and microstructure:

“For 70 years, aluminium alloys have been the materials of choice for both military and commercial aircraft structures. The ingot metallurgy (IM) alloys of the 2000 (Al-Cu-Mg) and 7000 (Al-Zn-Mg-Cu) series used thus far show several disadvantages caused by the production process. Such problems are primarily coarse intermetallic constituent phases, coarse grains, and macrosegregation, resulting in low fracture toughness.”
Mechanical Properties of Spray Cast 7XXX Series Aluminium Alloys (2002)
http://journals.tubitak.gov.tr/engineering/issues/muh-02-26-4/muh-26-4-5-0106-6.pdf

Properties Of 7075 Aluminium Alloy Extruded From Rapidly Solidified Flakes And Conventional Atomised Powder [abstract] (1984)
http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADD458269

'Effects of Dispersoid Particles on Toughness of High Strength 7000 Aluminum Alloys'
KEY to METALS ? Nonferrous :: The World?s Most Comprehensive Nonferrous Metals Database

“Q: Why is aluminum alloy 7075 not listed in AWS D1.2, Structural Welding Code - Aluminum?
A: Most aluminum alloys are weldable, but a fair number of them are not, including 7075 aluminum....However, 7075 should not be used for structural work.”
Welding FAQ Welding consultants for welding inverters, welding machines and other weliding & cutting systems
[Of course, 7075 is weldable, but the results are often bad. Layers of liquid may form parallel to surface, along the rolling or extrusion direction.]

Thermal Stability of Rapidly Solidified Alloys of Aluminium with Transition Metals [1st page only] (2006) Thermal Stability of Rapidly Solidified Alloys of Aluminium with Transition Metals

Finally, you can identify 7075 by its speckled olive coloration when hard anodized. And, the intermetallics, if not well broken up/dispersed/homogenized, will appear as blisters in the anodize.