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80% receiver

8.1K views 8 replies 5 participants last post by  rlpryer  
#1 ·
How would you like to make your own FCG for the P320, an 80% receiver?

All one would need to do is take every part out of the receiver as it is, and take the stamped metal shell part that all the parts assemble into, and unbend it... make it flat. When flat, it could be laser cut/duplicated and the exact position and size of each hole would need to be marked on a blank piece of Stainless Steel. You then would drill and ream the holes (precision is key), and put the now drilled "receiver" in a press and bend it into the right radius as the right place and you would have the receiver to install all the parts into MINUS the serial number that is on every manufactured firearm for sale.

You can make your own firearm, per BATF regulations. You do not need to serial number it, but must if you ever plan to pass it on to an heir or dispose of it. It must be yours and you must do the work to finish it.

I've done this with AR-15 blanks as well as one for my .308 where I had to mill out the area where the hammer and trigger go, along with drill the appropriate holes. Of course I used a jig, but they work extremely well.

The idea of the stamping out of the receiver I thought about as there are laser cut and drilled holes out there for AK-47 receivers that you can buy and have shipped to your house, via mail. They are nothing more than a stamped piece of steel with holes, usually one square opening (pistol grip) and sometimes they have the rails spot welded in place. You bend this part with a brake and assemble the rest from cut up AK-47 kits you can buy that have parts, barrel, etc, and build it. Same rule applies.

Since the AK-47 is a stamped part, surely it could also be done with the P320 as all it appears to be is a stamped metal part with the "ears" of the slide rail bent at the appropriate angle.
 
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#3 ·
When sheet metal is bent, stretching occurs on the outside of the radius and some small compression takes place on the inside of the bend. I would expect that straightening the bend will result in some distortion as the sheet metal will tend to stretch easier than it compresses. This distortion takes place in both forming and straightening operations, though it is accounted for in the original location of holes and such.

After straightening, I would expect some elongation of the workpiece and this may cause problems when trying to get accurate hole locations.
 
#5 · (Edited)
I seriously doubt a 3d printed unit would hold up for very many rounds,

but I don't know all there is to know about 3d print tech and the materials or their strengths, but I do Know it's EXPENSIVE!

My observations of 3d printed guns on the interwebs youtube and such tends to end up as Scrap unless reinforced with structure critical metal parts.

an idea of an Errector set of laser cnc cut metal with an 80% Flat concept is doable But the time to reverse engineer it would likely cost 80 to 100k+ usd, unless you have some retired engineer with cam design experience that just wants to take on a project as a hobby.
- a skilled engineer can factor in the expansion of the metal when bending it.
 
#6 ·
In this age of computer generation images, CAD, it would be possible to literally spread out the FCU as a flat piece, without distortion, and accurately figure in hole placements, and bend radius.

The factor of Patent does matter, as the AK-47 was long past design protection, and if memory serves me, it was never patented. It is the most stamped out firearm part used in weapon systems all over the world.

Getting the right internal parts, which are in HEAVY demand by SIG Sauer in their own weapons and assembly would be the real obstacle.
 
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#7 ·
It's been some time since I've obtained a patent, 1985 to be exact :), but some things haven't changed. A patent covering utility (features and how it's used) will be stronger than a design (appearance) patent. Like the outward design of a toaster, one has only to change the appearance to get around that sort of weak patent.

Not so with SIG's design, I'm sure. They would have patented both utility and design, assuming their lawyers have half a clue (and I bet they do!). Besides, a rubber stamp copy, as Gibbs rightly points out, would surely have problems in any event as you know SIG would be all over that as an infringement.
 
#8 ·
If there is a dollar to be made, SIG will want to be the one to make it. Sometime in the future, they could, although probably not highly likely, sell a 80% flat laser cut frame for home craftsmen, but it won't be cheap and neither will the cost of the new components,from SIG that will have to go into it to make it functional. Companies cannot just take their design feature and mass produce it. I think there is a bit more latitude with individuals making it from scratch for the purposes of the "individual firearm" regulation of the BATF... just not 100% sure. It can't be sold, traded or even bequeathed. But as I mentioned, that frame is only the small part. Buying all the internals would be a challenge. Heck you can't even get certain grips right now.