Is aluminum an A-ok material to make shotgun receivers out of?

mr00jimbo

mr00jimbo

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You'll notice that many shotguns are made with steel receivers, including the venerable Ithaca 37 and Remington 870. Others are constructed from aluminum including the Mossberg 500/590, and the Benelli M4.
I understand that shotguns operate at lower pressures than handguns, and that for many, the receiver is just a platform to hold all the parts in.

Is there any concerns about a gun like a Benelli M4, with an aluminum receiver, being able to reach high round counts that would rival a steel-receiver shotgun?
Or will it eventually crack/crap out quicker than a steel receiver gun? Any inherent disadvantages to using aluminum as a receiver martial on shotguns compared to steel? I have heard of stripped threads that needed to be helicoiled.

Your thoughts?
 
Hmmm, I've never given the aluminum receiver on my Baikal MP153 much thought... I can say that the gun runs and runs and runs...

Cheers
Jay
 
Just afew Aluminum gun receivers

-M1, M2, M3 and M4 Benelli
-Mossberg 590/500
-SIG P220 and up
-Beretta 92
-AR 10s and AR15s

If these can survive heavy combat and brutal round counts then I think you ok using it on a civi range ;)
 
Can't say I've heard of any problems specifically relating to aluminum receivers in shotguns, but I certainly don't claim to know it all, either.

Really it comes down to design. The specific operating pressure inside the barrel doesn't matter, and while I do believe that you're on the right track thinking about pressure, just not in the barrel. Barrels are going to be steel, and designed to take whatever pressure is going to be exerted by whatever they're chambered for. What DOES matter (to receivers) is the forces (and resulting pressure) that will be placed on the interfaces between the barrel/bolt and receiver. I would think that if a shotgun were designed with an aluminum receiver, these interfaces COULD be made to be larger in surface area than a steel receiver so that the resulting pressures would be lower, and so that the aluminum (typically softer than steel) would not deform, if that was even necessary in the first place.

My Winchester SXP has a rotary bolt, and the bolt locks directly to the barrel. When the gun is fired, the only forces being placed on the receiver should be at the interface between the back of the barrel and the receiver, which is a pretty large surface area, when you consider the only force being placed on that area is equal to the recoil. And also at the interface between the receiver and the stock... but that's an even larger surface area.

Perhaps on a design that is barely adequate using steel, and then someone produced a dimensionally equal receiver using aluminum... might cause problems.

Aluminum as a receiver material is good to go. :)
 
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In my engineering opinion, the shotguns material (or receiver) is not that important. The pressure in the chamber is contained by the barrel (or whatever houses the chamber) and the bolt. This is why bolts have lugs to lock into to place. The steels that the bolt and barrel are made from obviously have to be very strong to handle the pressures. It's also important to note that the the pressure is only applied to the chamber and bolt for a few milliseconds at best. Even though its a very high pressure, there just isn't enough time for the material to deform past the elastic region yet alone reach yeilding. In a sense this is similar to hitting a nail with a hammer. If you were to apply the amount of force on a nail that the impact of a hammer creates, the nail would buckle. However, because this force is brief in it's duration, the nail doesn't have a change to begin to deform. Furthermore, consider the keltec SU-16 - plastic receiver. I believe several other rifles (ACR and that new berreta one) have polymer receivers as well. Even though these polymers are very strong, they are no where near as strong a good old fashion steel.

I know in the case of an direct impingement action, there will be some gas pressure redirected into the receiver. Gas pistons actions will also have indirect forces applied to the receiver as well. As mentioned above, the receiver does also have to be strong enough to interface to the barrel. But in general, guns are designed to keep pressures in the chamber - where they belong :)
 
In 1978, Ithaca began making an aluminum received variant of thier M37 Featherlight shotgun, called the Ultrafeatherlight and later on the handle was shortened to Ultralight.
IIRC, they were made in 20 and 12 gauge only, but I could be wrong about this.
I'm sure it was some kind of high strength alloyed material.
 
I've heard that steel holds up much better to external impacts, like if the receiver is smacked off a door frame or other hard edge, but it's hard to say if it makes a big difference as far as round count service life.
 
I've never felt my aluminum receivers to be a weak point in any of my guns. In fact my Benelli M4 was probably one of the most solid feeling gun I've ever owned. I also have an old Win 1400 that was left to me by my grandfather, and that gun has seen decades of field use, and a ton of rounds, and shows no signs of wear on any receiver components. Unless you are swinging your shotgun like a baseball bat, I can't imagine it will make much of a difference. If you're concerned about cyclic wear, consider the pistons in your car. The amount of heat, pressure, and speed they are subjected to is certainly intense, and then consider the high mileage that many vehicles are reaching today, I would say aluminum is up to the job. Obviously it's important to remember that aluminum comes in a wide variety of alloys, and different alloys are better suited to different applications. I think with proper alloy selection, and engineering, there is no reason that it won't hold up in a receiver, and I think that's been proven in a lot of guns.
 
The bolt of Mossberg shotguns locks to a notch in an extension of the barrel so the receiver is there just to hold all the parts together. The Hatsan/Optima shotguns seem to have steel liners inside the aluminum receivers.
 
There is not much to worry about modern alloy receivers on shotguns,
other than having to use a different "blueing" agent to touch 'em up,
or recoating them in your color of choice.

Compressive strength of alloys in shotguns has been good since the late 50's,early 60's in
guns with proper, solid bolt to barrel lockup like Winchester 1200/1300/1400/1500's,
Benelli Nova's and the like. Mossbergs work good enough to be selected for US military
duty with only a single hook point locking the bolt to the barrel shank.

In all my years of tinkerin' on firearms, I've never seen an alloy receivered shotgun
have a catastrophic failure in the receiver, but have seen all sorts of split and
blown open or apart shotgun tubes.

Winchester even made the Model 59 auto 12ga. with a thin steel/fibre wrapped composite barrel
combined with an alloy receiver back in the day, and they were super light and reliable with proper
care. I've not seen one of these barrels burst in normal use.

The alloys used today, along with the advances in machining and design have proven themselves
more than up to the task. AR-15/M-4's for example.:)
 
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Yep, no worries at all with the Aluminum receivers in modern shotguns. Generally they are a bit thicker than their steel counterparts to give extra shock impact protection etc...

There have been older Benelli M1/M2's that have 250,000 rounds (of target shells mind you) through them for competition shooters, and the M4's are designed to take a minimum of 25,000 rounds of 3" magnum shells with NO parts failures of any kind, the receivers don't have a whole lot of stress so they're very unlikely to actually break.

I don't think a single person could EVER cause a firearm receiver/frame to fail because of metal fatigue... The weight to stress factor that airplanes have to deal with is multitudes higher than ANY gun with ever have to deal with, which is why they have such strict hour limits on all parts.

The corrosion resistance, lightness and general toughness of aircraft grade aluminum alloys make them a good material to work with, as long as you keep higher amounts of heat away from it.
 
recievers like brownings blr maybe made out of aluminum , BUT the bolt locks into the barrel not the reciever ( i'm pretty sure the ar 15 is something similar ) .

so the reciever does not handle any of the pressure of the round going off .
 
Brutus said:
In 1978, Ithaca began making an aluminum received variant of thier M37 Featherlight shotgun, called the Ultrafeatherlight and later on the handle was shortened to Ultralight.
IIRC, they were made in 20 and 12 gauge only, but I could be wrong about this.
I'm sure it was some kind of high strength alloyed material.
Click to expand...

There should be a not of caution on the Ithaca M37 Ultrafeatherlights. The bolt locks to the reciever in these guns just like the steel recievered ones and were designed for low volume shooting. I wouldn't pound too many high brass shells or goose loads thru 'em to be on the safe side.
 
Strange that nobody yet inquired about which alloy of aluminium you were talking about... Their mechanical characteristics differs.
 
x0ra said:
Strange that nobody yet inquired about which alloy of aluminium you were talking about... Their mechanical characteristics differs.
Click to expand...

Greatly. Most common is T6061, then 7075. Hell one company made this stuff called Fortal HR/HP and can be used as a direct replacement for 1020 steel. Higher tensile PSI, higher Yield and equal Shear. Amazing what you can do with alloying elements.
 
Blastattack said:
Greatly. Most common is T6061, then 7075. Hell one company made this stuff called Fortal HR/HP and can be used as a direct replacement for 1020 steel. Higher tensile PSI, higher Yield and equal Shear. Amazing what you can do with alloying elements.
Click to expand...

Yep, the only real downsides to the 6061 and 7075 are that they depend almost entirely on the heat treatment for their strength so if you heat them up to (if I remember correctly) over 200 or 250 degrees C they will lose their heat treatment. Not much concern for shotguns or AR15's or anything, but if you could make it as strong without needing the heat treat it would be a heck of a material!

And there are probably hundreds of different grades of Aluminum's (same as with steels), I used to remember what all the numbers in the names meant... First number is the primary alloying element (1 being Aluminum, 7 being zinc I think?) second is if there is a purification process (so 1100 series is pure aluminum, which is food grade safe) and the second two I think are the 2nd and third alloying elements, but not 100% sure on the last 2 it's been a while since I looked it up :p



Most aircraft grade aluminum alloys are incredibly shock resistant, and fatigue proof but of course anything can fail if it's flexed enough times, but for a shotgun there is so much "meat" to the amount of force being put on a shotgun it really shouldn't EVER fail.
 
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