Frame milling question

Ok, this is ALL new (except for the hours of lurking, research to convince myself to acquire a machine, etc. etc.). I want to build a few things from "scratch". On that list is a pair of 1911's and an AR platform. Probably an AR-10 type 308. 1911 frames seem to be mostly steel. AR lowers all seem to be aluminum in one grade or another. Is there a reason one could not mill a 0% from steel? I have access to and think I can forge a blank for both from what I think is Aluminum Bronze. It is hardened, anti-corrosion valve bronze of some kind (I haven't confirmed the metallurgy, but the price is PERFECT) and I can, with a little patience, have as much of it as I want. Forging steel into a usable "hunk" is a bit trickier, but on the table. I also can put my hands on "scrap" steel, including stainless. With the assumption this is a problem I want to tackle, thoughts and opinions?
FWIW, I have some non firearm projects in mind too. I just want to do the ones that go bang first

Fix your location.

the ar platform relies on a closed bolt, with all the firing forces internal to the barrel/bolt assembly, so there is NO reason to use steel (there are plastic lowers out there, too!). One big negative to using steel is the weight penalty (any part in steel will weight 3x as much as aluminum, holding all the dimensions the same). Machining will take longer, etc.

In short, why bother? The material may be free, but you can buy a forged 0% lower for $25 (AR15), so cost really isn't an issue.

I agree with Roy that the extra weight would not be desirable and milling some of the deep pockets in steel, let alone stainless (shudder) would not be a lot of fun. On the other hand, a lower/upper made from aluminum bronze would be kinda cool (still heavy though) and I'd be interested in seeing a forging.

JMHO

-Ron

Any bronze will have a serious work hardening problem IF it is hard enough to do the job. If Al Bronze was worth a shit for modern firearms the stores would be full of "billet" bronze shooting machines.

Royldean said:

In short, why bother? The material may be free, but you can buy a forged 0% lower for $25 (AR15), so cost really isn't an issue.

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If cost were the only issue, we wouldn't have very many discussions.
Yes, I can put my hands on a 0% lower for closer to twenty bucks plus a freight charge, but you can't do that with an AR-10 and if we are using that argument WHY would you pay twenty for a 0% when an 80% is thirty or a complete stripped lower in your choice of finish is less than eighty? It's a HOBBY. I ain't found a cheap one yet and I'm afraid this may be one of the most expensive yet.

If I want to do a "scratch" lower, aluminum is stupid expensive (I would probably feel worse about other options if cheap, quality scrap wasn't a ready option for me).

As to the Bronze......I just can't help but think it would look really kewl! and it would be much more durable than "plastic". I wouldn't want to try a 1911 frame out of it (or aluminum either), but a bronze slide might have the same appeal. The bronze piece I have so far is only about 3/8" thick. I would have to make a cast from it to get anything of any size. The dead center middle is big enough to get a slide out of without modifying it. Pins and triggers would mill from it very easily (well, not easily, but would fit from the material). IF I put together a setup to use the stainless for larger projects (sand cast and then heat treat later), I might have to figure out how to afford to shoot something bolt action like a 460 or a 50

tdmidget said:

Any bronze will have a serious work hardening problem IF it is hard enough to do the job. If Al Bronze was worth a shit for modern firearms the stores would be full of "billet" bronze shooting machines.

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Sure they would. Stores would be just chock full of a product that costs triple or better the other sources. I have to find out if what I have and can get more of is phospor bronze or Aluminum bronze, but it comes from an application where corrosion resistance and high pressure are the key factors. Steel won't hold up under the conditions these valves are in. I wouldn't even be considering it for ANYTHING if I had to pay for it.

azmachining said:

Fix your location.

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Ok, about 8 hours or so from you. I've got a buddy with kids in Prescott.

bigstarshot said:

With the assumption this is a problem I want to tackle, thoughts and opinions?

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bigstarshot said:

If cost were the only issue, we wouldn't have very many discussions.

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You asked for an opinion, and I gave it to you. You obviously just want to do this and this thread is an advertisement for your upcoming work. Go knock yourself out. Dollars to donuts the project never gets finished due to the above mentioned concerns, but please do prove me wrong. Good luck.

bigstarshot said:

Ok, this is ALL new (except for the hours of lurking, research to convince myself to acquire a machine, etc. etc.). I want to build a few things from "scratch". On that list is a pair of 1911's and an AR platform. Probably an AR-10 type 308. 1911 frames seem to be mostly steel. AR lowers all seem to be aluminum in one grade or another.

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The "MIL spec" ARs are 7075. ALL of the forgings I have seen are 7075. Billet lowers are whatever they made them from. 6061 is not as strong, but unless you are pounding tent stakes (or anything else) with the butt of the rifle I doubt it will make much difference.

1911s would be made from 4140, 4340 or a hardenable stainless.

bigstarshot said:

Is there a reason one could not mill a 0% from steel?

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None whatsoever! Any flavor of steel would be stronger than the plastic lowers out there that DO work. It would be a bit on the weighty side though...

bigstarshot said:

I have access to and think I can forge a blank for both from what I think is Aluminum Bronze. It is hardened, anti-corrosion valve bronze of some kind (I haven't confirmed the metallurgy, but the price is PERFECT) and I can, with a little patience, have as much of it as I want.

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Heating any "red metal" hot enough to forge it will anneal it removing any temper that it did have. Re-hardening it would be a difficult task with out extensive knowledge and skills. So I would assume any bronze forging you were to do would NOT be hardened any longer. Second, as already mentioned, bronze will work-harden and is prone to stress cracks as a result. MAYBE not a huge problem in an AR lower but MAYBE it would be... Have not really looked into doing a lower out of copper alloy due to issues with red metals in firearms in the past. Copper alloys are just not a good choice for firearms in general. History has proven this to be fact.

bigstarshot said:

Forging steel into a usable "hunk" is a bit trickier, but on the table.

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I can see little purpose for forging a steel lower sort of saving your self a little time on the mill. However, unless you were making MANY of them, the time to make the forging dies would be greater than the mill time. I just don't see what's to be gained.

bigstarshot said:

I also can put my hands on "scrap" steel, including stainless. With the assumption this is a problem I want to tackle, thoughts and opinions?

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PERSONALLY, I would skip the bronze firearm idea. The probability of a crack is greater than I am willing to accept. Forging a steel part for one or five firearms is one I would not entertain due to the time involved in making the dies. I had considered it for the bolt handle for my .50 and dropped the idea for that reason. It may come back up when I do a smaller bolt action as I would be likely to do more of them over time.

No one but you knows your motivation for your projects so it is not possible to tell you what you "should" do. Just keep in mind the properties of the materials you are working with SHOULD be front and center in any project. More so when life and safety are on the line.

bigstarshot said:

FWIW, I have some non firearm projects in mind too. I just want to do the ones that go bang first

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bigstarshot- see turnbullmfg.com/gun/turnbull-tar-15-rifle/
looks doable, and cool.

bigstarshot said:

... As to the Bronze......I just can't help but think it would look really kewl! and it would be much more durable than "plastic".

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Depends on what you mean by "durable". More wear resistant? Sure. Less prone to stress cracking??? Not necessarily?

bigstarshot said:

IF I put together a setup to use the stainless for larger projects (sand cast and then heat treat later), I might have to figure out how to afford to shoot something bolt action like a 460 or a 50

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Another idea I would PERSONALLY avoid. Making a bolt action "460" or "50" from a "sand cast" hunk of stainless without the ability to know if there were voids in the casting... HELL NO!!! I would NEVER EVER trust "scrap" metals to be anything other than the weakest possible alloy. 304SS or even 1018 could work for an AR lower... But for a .50BMG bolt action??? The action alone would weigh in at 50 - 60 pounds and would be prone to lug set-back!!!

Can you tell me the properties of 416 SS with 10% 304 added to the pour? Is it still heat treatable?

If you can't afford steel of KNOWN properties move on... The life you save may be your own!

I suggest knives. They dont blow up when your forgings have cold shuts in them, or when your sand casting has totally altered the chemistry of the material.

Both Aluminum bronzes and stainless can, indeed, be cast. But doing so at home, you will completely change the alloys. Industrial casting of stainless is done in controlled atmospheres, and sometimes they actually add things in the melt, and they often do real time chemical analysis.

Whatever alloy you start out with, after casting it, it wont be the same.

But hey, make whatever you want- just make sure, the first few hundred times you fire these things, nobody else is within a few hundred yards.

You can't just melt a rolled piece of metal and make a satisfactory casting. Cast alloys will have something , usually silicon, to improve flow characteristics so that a mold is fully filled. There are other changes too and the melt conditions are not just an open crucible in many cases. This is a dumb idea for something critical.

DrHook said:

bigstarshot- see turnbullmfg.com/gun/turnbull-tar-15-rifle/
looks doable, and cool.

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interesting. So a steel, shooting safe queen isn't a complete white elephant. That would look/be much cooler with real wood IMHO.

Royldean said:

You asked for an opinion, and I gave it to you. You obviously just want to do this and this thread is an advertisement for your upcoming work. Go knock yourself out. Dollars to donuts the project never gets finished due to the above mentioned concerns, but please do prove me wrong. Good luck.

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No, you sounded off with a non-opinion about the bronze. You made the idea of using the bronze sound cheap and unprofessional. "if aluminum bronze were worth a shit..." when in fact aluminum bronze is used a LOT in critical applications at a 3+ times cost factor over aluminum and more over steel. I was looking for and am reading some great advice on the viability of options for projects I have in mind.

A lot of great information being thrown my way with this. I obviously need to read and investigate more on forging. I might be better off using what I have for smaller parts and acquiring the larger pieces another way. I did not mean to imply that I would cast any actual parts. The purpose for casting would be to cast a straight bar or shaft that could be milled or turned down to the desired size and shape. Yes, I realize that is a LOT of "wasted" time milling or turning, but it is time I spend in the shop doing something and learning. I do not know if I can verify or properly assay the forged metal. I do believe I have the contacts that could confirm the integrity of the casting. The tools used to check and verify large welding projects should be able to confirm the integrity of a cast block or bar. Again, local contacts do weld and verify their work and could check my material for me. It might cost me some beer, bourbon or both.

Again, I'm not doing this to save money as much as I want to learn how it all works. Making an aluminum forging would be fun and challenging, but I KNOW I do not have access to the right materials to make a good enough quality aluminum to get anything that would be functional. A steel or bronze AR would be stronger than any poly lower out there. Even an AR-10 should function from said material IF it tests good.

bigstarshot said:

... I KNOW I do not have access to the right materials to make a good enough quality aluminum to get anything that would be functional. A steel or bronze AR would be stronger than any poly lower out there. ...

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Poly lowers work because they're strong enough. Is stronger necessarily better? (back to pounding nails ...?)

Is that you get a material for free any reason it's what's best? (Maybe 'better' is enough.)

I suggest setting up some of that free stock and milling or drilling a few cuts. If you can do so & have anything left of your tooling you're probably ready to handle any material short of inconel or stellite.

OP, what is the original use of this Mystery metal? This is not a matter of national security so it's OK to tell us. Your location makes it kind of obvious. Maybe someone here can tell you exactly what it is.

tdmidget said:

OP, what is the original use of this Mystery metal? This is not a matter of national security so it's OK to tell us. Your location makes it kind of obvious. Maybe someone here can tell you exactly what it is.

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bigstarshot said:

I have access to and think I can forge a blank for both from what I think is Aluminum Bronze. It is hardened, anti-corrosion valve bronze of some kind (I haven't confirmed the metallurgy, but the price is PERFECT)

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Not a "mystery", just an unknown specific. I do NOT know the brand on this particular valve. I therefore am unsure of what quality of Bronze material was used to make the corrosive resistant valve. I am reasonably sure that is should be phosphor bronze, but it could be aluminum bronze. Sometimes price drops a lower end product into the equipment. I also am not 100% sure which piece of equipment the mechanics took this particular treasure from. It could be from one of the "new" pieces we got last year and if it is a factory installed valve, it might be a "cheaper" one. I saw it in the scrap bin and grabbed it. I'm not the only one watching the scrap bin. I've seen some really cool projects turned from some of the axles that end up in the scrap box. If I were forging and could get the quality right, you would not believe the amount of quality valve steel I watch go to the scrap bin each week for something around nine cents a pound. So far, scrap has been first come first serve with the balance going to a roll off. I don't mess with the roll off. If it gets that far, I pass. I missed a couple of stainless shafts that I really wanted.