1911-ish

Even though my Uzi isn't done yet, and I have a thousand other projects going on at the moment, I decided to start another one.  Some time ago I made a complete 1911 pistol from scratch on the CNC.  On that one, the frame was made in two pieces, left and right halves, with some of the pins replaced with screws, as well as a few screws added in other places.  That made it very easy to machine in just a few setups.  It was mostly aluminum with 6061 for frame and 7075 for the slide, but it's just a 22lr so I wasn't really worried too much about strength.

I decided that I wanted to make one in 45acp though, as a proper 1911 should be.  I didn't want to do the left/right half thing again, not really trusting a bolted together frame in 45.  I could do it in steel and silver solder the halves together, but as mentioned several times in my Uzi build, I hate machining steel.  Making a complete one piece 1911 frame from any material involves a lot of odd setups and careful machining, and I am far too impatient for that.  The available 80% frames don't really hold much interest for me either, I like doing everything myself.  Fortunately, there's another way.

I'm going to be building this 1911 like the STI 2011 pistols.  It's going to use separate upper frame and grip sections.  I'll be using an off the shelf slide and Sarco parts kit for the hard parts, I'll CNC an upper frame from 7075 aluminum, and the grip section will be 3D printed.  I hope to have under $250 in the whole thing.  Here's the the CAD work I've got done so far.  All the important bits and anything that needs to be very precise is in the upper frame, and you can see how the upper and lower will be split:

I'm reasonably confident that a 3D printed grip section will be strong enough, all the real load bearing areas are in the upper frame.  The area around the front upper grip pin and trigger guard is much thicker than standard, and the sides of the mag well have a big rib going down them to add some extra strength to the print.  The only part I'm really concerned about is the pin that holds in the mainspring housing.  The pin hole area is thin to begin with, and I think it'll break on a printed part(that's the little hole on the bottom right of the grip frame in the pic).  Fortunately, I have a plan for that too.  I'm probably going to make the grips from aluminum.  The top grip screw attaches to the upper frame and the bottom goes into the lower, so I'll basically have metal supports running the full length of the grip frame.  I'm going to make the grips so that the mainspring housing pin goes through them too, giving it some extra support.

I'm going to try not to drag this project out too long...

I may look stupid, but I'm not dumb

So I finally got all the pieces of the Uzi made and fitted, and working the way they're supposed to.  The only thing left to do was test it before paint(because I didn't want to paint it and find out I still had to grind on something).  While I am prone to making poor decisions, I try not to do dangerous things with guns.  Especially guns that I've made.  Double especially guns that I've made that have essentially just sheetmetal between explosions exploding and my face.  So what's a guy to do?  Get a long rope and hide behind a tree of course.  So I clamped the gun in a portable workbench and tied a rope around the trigger and pulled it from behind a big tree.

Started with one round in the gun to make sure it wouldn't explode, then stepped up to two and then three to make sure it worked as a proper semi-auto.  So how did it go?  Well, it didn't explode, and every round that it chambered fired.  But it also didn't work great.  Just about every other round FTE'd.  Stovepipe after stovepipe as the spent casings didn't want to leave the gun.  I also noticed that the casings that did properly eject didn't go far, maybe a foot or two.

I spent some time troubleshooting, tweaking my top cover clearance(which should be around .010" ), making sure everything moved nice and free, testing both mags I have and getting the same results, and finally thinking that maybe my new bolt actually needed the big ejection scallop cut in it that the factory semi Uzi bolts have(which I very much didn't want to add). 

And then I remembered to actually watch the video I'd taken.  Seeing it in slo-mo, it was clear that the bolt was short cycling, i.e. not going back as far as it should.  Between the short cycling and the spent casings not ejecting with any real force, it occurred to me that maybe the gun was fine, but the ammo wasn't.  Up to that point, I'd been using some Armscor 124gr FMJ that I bought many years ago but never used when I started a Suomi project(that never got finished...).  While it's probably fine for other 9mm guns, it just didn't seem zippy enough for the heavy Uzi bolt.  So I bought a box of Winchester NATO 124gr FMJ, which the internet told me was pretty hot, and my FTE problems went away.  Not only were the cases ejecting, they were now flying out and landing 8'-10' away.  Let that be a lesson, if something seems amiss with a gun, try some different ammo first.