I've had a few questions about how I got an AR down under 30" to attain "Michigan Pistol status.


I was a bit worried about reliability, but this rifle has at least 300 rounds through it without any faliure.  I just stopped shooting it for a while till I rebuild it as I actually want it.  I kinda cannabalized a few other guns to test this idea out.  

Here's what I did.....

This lower was bought on the old 4473, and was transferred to me as a rifle.  That requires a 16" barrel. So, I started with a Brave Company 14.5" midlength upper with a pinned and welded flash hider.  I need to make this rifle as short as possible, so as little length on the front end as possible was my goal.  This upper was bought for another rifle, I still have to make a similar upper for this.

Standard lower parts, bolt carrier group, charging handle, and an A1 carry handle I had available.  

All I need is a short stock and recoil setup.

I didn't come up with this idea, I just modified it to work for me.

GSE Makes their 1st generation pistol buffer tube, I had one of those.  It worked well for me on a pistol.



With a little measuring and drawing I made a shortened buffer tube, and a spacer with a guide rod pressed in it.  You'll need a 1 3/16-16 die and some oil for threading.  I locked the die in a vise, and used a strap wrench to run the tube down.  The buffer tube has to be commercial diameter.  A milspec tube is too small to thread.  (the tube is actually smaller in diameter than the threads).



Pretty simple really.



Spacer goes down the tube.


The rest goes on top.  You have to put it together with both pins pulled.  It won't pivot on the front pin.



Comes in just below 29.75" long collapsed.


And short but very usable 33" extended.



Edited to add more details.

Pretty awesome idea. Have a chance to shoot her yet?

I'm pretty tempted to pick up a lower and try this myself...

Yeh, runs like a champ.  Slow fire, fast fire.

No probles in 300+ rounds.

That's one sharp rifle as well.  Now I guess I'm showing my newness to modding here, but with regards to the buffer tube...  how did hte stock attach? Or is it that the threaded end of the short buffer, you threaded the com buffer tube onto that?

ETA

I get it, the comm buffer was cut off at the receiver end and re threaded, gosh I'm an idiot lol, I cant believe it took me that long to figure that one out, the dual threaded piece was just used as a template.  How do you go about filling out the pistol registration form for this, just put yourself down as both the seller and the buyer?

Awesome, reliability was my only worry about taking on a project like this. But that could be fixed if it ever became a problem.
Did you have to trim the stock at all to get it to fully collapse on that tube?



You got it, you'd be the seller and the buyer.

Yeh, you'll need to thread the buffer tube before you cut it, so you have a decent way to start the die on it.





I was quite worried about reliability too.  While 300 or so rounds isn't a major torture test, it's enough to convince me to take this rifle seriously when I rebuild it.  I've had plenty of guns that never went 300+ without fail.

Yes, I cut about an inch off the front of the stock to get it to collapse.  I've seen a few other types of CAR and M4 stocks that look nicely trimmable as well.  I don't really like the CAR stock.  it's a little sloppy, and the butt is kinda flat.....but for free I didn't care.

I'm going to revise the stock pretty soon (little shorter, and better body), but If anyone is gonna get into doing this, I'll get some sketches and measurements for you.  

Another suggestion would be a set of YHM EZ-Pull pins.  I have them on other rifles, and they really need to be on this.

How much length did you cut off the tube ? Would it be possible to shorten the buffer and or the carrier to keep the original configuration ? I had one of those buffer setups and sold it. After seeing this I wished I still had it nice work.

Thanks

Not sure exactly how much I ended up cutting off.  A couple inches at least.  I'll measure it when I get home from work.  I just kept threading it and cutting off a half inch at a time till I had what I wanted.  Then made the spacer to match.

I would think you could shorten the buffer or carrier, but something will have to be altered from original configuration.  Take a look at GSE's gen2 pistol buffer, it looks like exactly that.  I had visions of trying to make one similar, but after running this a while I don't think it's necessary.  Plus, I'd prefer to keep the carrier unaltered.

I have also been considering making a different spring adapter for the carrier, to add some more moving weight.  Again, this seems to work, so it's kinda low priority.

I haven't had a tape out in a while I didn't think that much needed removed? Yes I would hate to mess with the carrier but two inches would be a lot off the buffer. Maybe weight in the carrier would off set the weight cut off the buffer ?
Its always fun to try different stuff but you have the problem solved.

I guess it wasn't that much.

The buffer tube in the pictures measures 6.130".

I believe 7.25" is what it was originally.

So I cut off 1.120".

I need to cut more off if i want to try something other than a CAR stock though.  Other stocks have a solid butt.

Had some requests for more build info.

First off, this is the way I chose to do it.  I'm sure there are many other ways.  My main goal was getting under 30" for as little money as possible.  I had no Idea if it would work at the time.  I didn't want to throw money away.  I owned the complete rifle with an A1 stock on it, and had the GSE pistol buffer.  All I needed was a stock.  I got a stock for free, and my only expenses were the die, and a pack of washers.

I did a lot of this freehand on a belt sander.  Just trial and error adjustments.  Most of the numbers I'm stating are pretty fluid and can be adjusted.  They need to be in order to run the gun.  I'll explain how I did it so it all makes sense.  

First thing I did was thread the buffer tube further.

You'll need at least a pair of 6" dial calipers to measure.

You'll need a 1 3/16-16 die.  It's a standard, but uncommon thread.  You probably can't find one locally.  I have access to a pretty amazing supply of metalworking tools....I had to buy one.  You'd have better chance of convincing some guy on the internet to loan you his.  This is the one I ordered.

It HAS to be  commercial buffer tube.  They are larger diameter and have lathe cut threads.  Mil-spec tubes are smaller diameter, and the threads are rolled.  The OD isn't big enough to cut a whole thread onto.  

I just kept threading a bit at a time till I got the length of the rifle with no stock body down to 29.75".  I didn't go any shorter because I wanted the gun to be as long as possible when it was extended.

I didn't extend the keyway for the key in the receiver back plate.  I just didn't want to, I filed the key out of the plate.  

Measured out mine looks like this all done.



Then the stock body had to be cut, easy enough.  Cut mine at 5.25 inches long.  I left it as long as I could to help with sloppiness when it was extended.





The CAR stock body has a hole in the ass, lets the stock get shorter.  If you use a different body, some don't have the hole and the buffer tube will need to be cut shorter.


Get that all assembled on your lower. Take the hammer out of your lower, it makes the next part easier.

This is a sketch of the spacer and spring guide.  I used a piece of 5/16" stainless rod, and turned down a piece of nylon for the spacer.  The rod was knurled at the end,  pressed and bonded into the spacer with loctite.  

I press fit this together, and used as little clearance as possible on the nylon OD to the the guide rod as squarely aligned as possible.

Check the dimensions of your buffer tube when finished, You may need to make adjustments to this piece.



Once you have that, drop it down into the buffer tube.  I wanted the end of the spring guide to be as close as possible to the back of the bolt carrier.  Help keep everything aligned properly.  I used a belt sander to adjust the length just short enough to put the upper on.



Here I was presented with my first problem.  under recoil, the spring will fully compress and the bolt carrier movement will be stopped when the firing pin hits the spring guide.  NOT GOOD.



A stack of 5/16 flat washers change that.  Now the movement is stopped when the back of the carrier/spring adapter hits the washer stack.



Now you have solid against solid.  Dont want to batter the gun.  Add a rubber washer and another flat washer to support the spring.  There is a nice gap now.



Make sure the carrier travels far enough to the rear to pass the bolt catch.  Make sure the bolt is cammed out, like would be under fire.  When I snapped this pic mine was wrong.



My final washer stack.  Two flat washers, the rubber, then one flat.  Total buildup of .387"  Firing pin is clear, and bolt catch works.



Assemble the gun, and cycle it by hand.  Check clearance and interference.  When you feel confident, go shootin.

Good Luck.

I did the same type of thing, except that I cut down a skeleton stock to get under 30".  If you have any issues with the GSE kit, try the second generation kit.  It is stock bolt carrier that has the rear couple inches turned down a bit to create a spring seat.  It uses a normal carbine spring.  I have not had any issues in maybe 100 or so rounds.  

I considered making my own bolt carrier for exactly that.  Just after testing this out, and having no problems, I haven't found the motivation to invest money in an alternative.

I also considered the Carbon 15 system, but again, haven't found the need.

What kind of skeleton stock did you use?.....does it extend?.....I would think a standard skeleton stock cut to under 30" would be way short and nearly unshootable.  Unless you're Mini-Me.

I used an Ace skeleton stock.  It is fixed.  IT is a bit on the short side, but it works well.  I will probably end up cutting down a carbine buffer tube and doing what you did.  I have to say, its nice to be one of possible only 2 DI Mi pistol AR owners.

There's one more I know of under construction.  But there cant be many.

What spring weight are you using in your GSE tube. The GSE that I have won't chamber the round properly.It seem to me the spring is not strong enough. I have to push the forward assistance every time. I use the 1911 26 lbs spring.

Thanks,
Cal

It's the stock GSE spring that came with the kit.  I haven't fiddled with the spring yet.  

I do know from a quick comparison, you'd need cut a "longslide" 1911 spring.  The spring is longer than a standard 1911 spring.  Perhaps that could be your problem.