Stocking up.

I did some more work on my SCR stock.  Not so geometric shapes like this are hard for me to do, it's not really something Solidworks was made for and I'm learning a lot as I go.  I actually printed two more stock sections in the past few days.  I got the first one off the printer and thought "Geez, this doesn't really feel different than my first attempt."  And that's because I printed the same original test file again...oops.  So then I printed the right one.  It's much better and is a much more comfortable grip and easier/shorter trigger reach.  It still needs more work as the base of my thumb sits uncomfortably against where the main section of the stock meets the grip portion.  It's hard to show the difference, but here are the two versions together showing how much lower the grip section of the new one is.  This one is also printed in Marble filament because I think that's what I want to use for the final stock/handguard prints.  I live in WI after all, and winter is a thing we generally do pretty well.

For ease of use, I chose to dovetail the stock onto the receiver.  That should give me a nice strong connection while only needing one small bolt to hold it in place.  The dovetail also gives me a lot more solid material in the area where the lower is most likely to break in use.  If need be, I can add a hole or two in that area to JB Weld in some steel reinforcing rods too.  You can see how it slides on here:

The first of many

I got my first SCR type lower receiver printed.  This print was done quick with minimal shell thickness and infill because I'm just checking fit and function, and is in no way shootable.  I also printed out the grip chunk of the stock so that I could see how it felt in the hand.  Even though I'm never going to attempt to fire this one, for legal reasons(namely the short section of test grip), this is a pistol receiver.  After playing with it some, I've come up with a list of things to work on.  First, I'm going to flip the safety lever to the other side.  It's not thumb reachable on the left side, but is index finger reachable if the lever is on the right.  Second, the grip is way too high.  I've got average sized hands and while I can reach the trigger, it isn't really comfortable so I'm going to move the grip down and forward some.  Speaking of the trigger, it does work, but as expected the pull is very long and creepy.  I'll work on making something better for the next one.

New project time.

So I saw a picture on the internet the other day of what appeared to be a 3D printed AR-15 based bolt action rifle with a traditional rifle stock and I got inspired.  In reading some discussions about it, I became aware of the Ares/Fightlight SCR which is basically an AR platform but with a standard rifle stock and no pistol grip, and I decided I wanted one.  Actual SCR lowers though are $600+ and I'm definitely not going to spend that much.

Good thing I have a 3D printer.  I'll just make my own.  I'm not going to try to make a fully printed rifle, I'll use an off the shelf upper.  The plan so far is to make a printed lower/stock, and use an off the shelf upper receiver and BCG.  This will be a straight pull bolt action rifle, so even though it uses AR parts, I won't need a gas system or buffer tube(the buffer tube is the big one because without it I can shape the stock however I want).  Since the back of the bolt carrier doesn't do much and is in the way on a rifle like this, I'll just cut it off.  I'm going to make it in 7.62x39 because I already have plenty on hand so I'll be using an x39 sized BCG, barrel, and 10 round magazine.

In reading about it, I've learned that 3D printed ARs(and many plastic ones in general) break at the buffer tube tower.  There's a lot of load on that area because of the bolt cycling, but since this will be a bolt action instead of semi-auto I don't need a buffer at all and it just needs to be strong enough to not break if I bonk it into something.

Using a picture for reference, my new lower started as a pretty straight up copy of the SCR lower.  But it wasn't really ideal in my eyes and wasn't suitable for 3D printing.  So I started changing and modifying and tweaking things as I saw fit.  The biggest change I made, other than the whole no pistol grip thing, was to move all the fire control parts up in the receiver .200"  This allows for a shorter reach to the trigger and an overall shorter lower receiver.  You can see here where the new location is compared to the standard AR, the new parts are the darker grey:

Next up was the trigger it's self.  Obviously it has to move backwards a few inches to work with a standard rifle grip.  My temporary solution is to just make an extender sleeve for it.  This is still very much a work in progress and will probably be replaced with something better.  For the time being I'm leaving the original trigger intact, I'll cut it down when I'm satisfied with how it works.  Since this is a bolt action rifle, I don't need the disconnector so the new printed trigger extension slips right over the tail of the original one.  I'll probably eventually make something with some kind of linkage, for now this is just a "see if it works" solution.

Here's where I'm at now.  I relocated all the FCG parts, added reinforcement in some areas because this will be 3D printed, and I got started on drawing the stock.  I got rid of the bolt catch too, it's not really needed anymore and the print will be stronger without it.  The stock is dovetailed onto the lower, and will have a single attaching screw running into it.  I'm not really happy with the stock yet but it's a start.

That's that.

The Gun Kote Flat Black actually turned out to be pretty close to whatever finish Rock Island uses on their slides.  I decided that the machining on the grips looked to good to cover, so I left them bare aluminum.  I'm not super pleased with the finish on the frame though, so I will likely repaint it.  It will do for now.  As I said last time, all that's left is to put the slide on.  It goes on like any other 1911 slide.  The only other thing I did was put in an EGW shock buffer on the recoil guide to keep the steel slide from smacking the aluminum frame.

Who likes beauty shots?

Closer

Getting close to the end now.  My 1911-ish gun gets assembled like a 1911...ish.  It's mostly like a 1911, but not quite.  I mentioned that because of the integrated mainspring housing this thing is a bit fiddly to put together and has to be done in the right order, and here's how to do it.

Start by dropping in the trigger.  Then the sear spring gets slid down into it's recess until the tab on the spring clicks into the slot in the magwell.  To help keep it in place, a roll pin goes through the grip right behind the sear spring.  The pin doesn't need to be a tight fit, the grips will hold it in place.  The mag release can go in now too.

The next bit can be tricky the first time you do it.  We have to install the mainspring into the housing.  I use a screwdriver and the edge of the table to compress the spring.  Gotta be careful not to slip and stab yourself.

Once the spring is compressed far enough, drop in the mainspring retainer pin through the hole in the MSH.  It goes from the outside in, just the opposite of a standard 1911.  It's only there as an assembly aid and will be removed later.

Next up is to put the frame on the grip section.  Install the sear and disconnector in the frame, then slide it together.  I use a hook to pull the sear spring back out of the way so that it can be put on the correct side of the sear.

Next up are the grips and the pin in front of the trigger guard.  They should be a tight fit because you don't want any play between the frame and grip section.

Next is the hardest bit, installing the hammer.  You've got to compress the mainspring enough to get the hammer lined up so you can drop in the pin.  I've found that the easiest way is to make sure the hammer strut is lined up in the mainspring cap, then press hammer against the edge of the table with enough force to get the pin in.  Get the angle just right, and it's not too bad.  Once the hammer is in, you can pull out the mainspring retainer pin because it's not doing anything anymore.

Next is the grip safety.  My printed GS slides straight into the back of the frame, then cock the hammer and install the safety lever like a standard 1911.

That's pretty much it, the frame is completely assembled.  Check everything for proper operation, and then install the slide like you would in any other 1911.  I'll add too that I'm using an EGW shock buffer on my recoil guide, just to keep the steel slide from smacking the aluminum frame.

The finish is in sight!

I'm not really a big fan of the two tone frame/slide look on 1911s, so I had to do something with my bare aluminum receiver.  As luck would have it, I have a little bit of KG Gun Kote Flat Black left over from my Uzi.  It's not a perfect match to the Rock Island slide, but it's close enough for now.  Someday I might completely refinish both in the same color, but that day is not today.  I really like Gun Kote.  It's durable and it's just so easy to use.  Prep your part, spray it on, and bake.  It leaves a thin, hard, and fairly durable finish too so I sprayed the whole receiver, rails and all(300 rounds so far in my Uzi shows no wear at all on the Gun Kote where the bolt slides against the inside of the receiver).  Here's my frame, fresh out of the oven.

Getting a grip, safely

In order to save an entire $30, I decided that I wanted to 3D print the grip safety on my 1911-ish.  I figured that if nothing else, it's already a back up to the main safety so if it didn't work the gun would still be safe to use.  I had a surprising amount of trouble with it, and it took several tries to get it right.  Because of my integral mainspring housing, an off the shelf .250 radius 1911 GS would still work, but will need the little feet trimmed off the bottom in addition to all the standard fitting that you'd need to do so that the GS can be put on after the upper and lower parts are assembled.  Here are all my attempts next to the steel part that came with my parts kit.  Each one is just a little different than the previous version: