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.45 acp carbine build, advice Is welcomed

warwickben

warwickben

bubba Kalashnikov
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I've been working on a .45 acp carbine build off and on for a few months.
I was just going to convert a ak. But I realized I had plenty of metal kicking around I could build one from scratch and really only have to buy a trigger (or trade ) and buy a barrel. It's gonna look a little like a m3 grease gun since I'm doing a tube style blow back . I'm really just flying by the seat of my pants at this point.

I've gotten the bolt roughed out and I'll finish it up once I get a grease gun mag so I know how much to remove on the front half. To clean and feed from the mag.


I can't sneak a barrel blank into work to use the lathe there so I've been trying to find a barrel for some time and that's been the biggest hold up. Uzi 16" barrels are allways out of stock and I didn't want a finned Thompson barrel.
Well I found a 16" 1911 barrel that I'm gonna try to use . It will fit in my lathe so if I need to do any thing to it I'll be good there.


This is were I'm at with the bolt.
epudybug.jpg

Yes that's a drill bit I have stuck in there . I'm using it as a slave pin till I figure out the finale spring for the extractor . Rather not press a pin in and out over and over.
Once I machine the front of the bolt out to clear the mag I can do some math and shorten the bolt up so it's still 2lbs. Since I'm doing a non delay blow back I need to be around two pounds. But since the hammer causes drag I can be a little lighter .

I thought about just buying a grease gun bolt then mod it for a firing pin. I know on open bolt guns the bolt can be less then a normal blow back bolt. Didn't feel like paying money . Modding it then figure out how to add weight.

One thing I'm stumped on is what I'm gonna do about the ejector .
Should i try a ar15 style pin. Or cut a slot in the bolt and do one like a ak.
Also trying to figure out the thinnest wall pipe I could use on the receiver.

Any tips , advice, free parts I'll gladly take lol .
 
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jhagberg88 said:
ill give you my first born for that pack of .22LR
Click to expand...

If your first born is a female and between 21 to 30 years old in.


I've found tubing I can use . Roughly 25$ for 3ft . Should be enough to build and do testing to figure out mag height and closeness to barrel. I got some blue prints for a grease gun but the don't show this in detail.


If any one got a ak or ar trigger or grease gun mag they don't need I'll take it btw lol .
 
I will check to see what I have for trigger groups. I may have one of each, but can't remember specifics. I have all the ak parts except for maybe the springs.


Sent from my iPhone using Tapatalk
 
Mgi military out of Maine has 16" 45 barrels that are for blowback. They come with a very generous feed ramp too. The chamber onmine is very very tight. My cast bullet reloads won't drop into the chamber because they are about .002 fatter than jacketted. Jacketted ammo drops into the chamber fine. Reaming the chamber should solve this.

Are you using steel or aluminum for the receiver? Steel you could probably get away with something as thin as an AK, like .050 or so I don't know how thick the receiver is on those off the top of my head. Aluminum, you are probably looking at 1/8 to 3/16. Copy the thickness of other gun designs at least as a bench mark.

I would be inclined to copy the ar ejector because I'm familiar with it and it would be easy to reproduce. But I'm sure other extractor styles are too.

I'm in the process of building a DI AR in 45 acp using all regular AT parts plus the mgi barrel and modified grease gun mags. Same as you, I am having a hard time with getting access to a lathe that I can put the barrel in (have to modify it for gas system). The only thing it won't do is last round bolt hold open. I haven't given up on getting that to work either yet.

Good luck with your build. I'll be following it
 
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Mgi sold you a barrel? I emailed them before and they told me they weren't sure when if there ever gonna have .45 parts again. I wanted to build a ar in 45 for some time with wood stock to go with my dads tommy gun . But the few people making .45 parts are charging so much.

I know the guys making the di .45 uppers are just using .458 socom bolts with custom barrels with the gas block right near the chamber .


I'm gonna use 4130 1.625 tube with a . 065 wall.

Ak's 1 mm = .039 ish or 1.5 mm is .059 so I'll be more then safe with the .065 tube for blow back.
I could of gone with a 1.5 od tube but with it being a hair bigger my bolt can be shorter .


As it stands right now .
Not including a mag I'm gonna only have 100$ into it.


$75 for a 16" 1911 barrel.
25$ for the pipe/tube.
I have a ak grip some one gave me . A spare ar firing pin
If I can get a free trigger every thing else will be scrap metal I have .

If I do the ar style ejector it will save problems of trying to cut the grove for the ak style.
I thought about just buying a .458 socom or a.308 bolt from a ar/ar10 and boring the bar stock out and pinning them in since they both work with 45. But I wanted to try to make every thing I could...


I looked at taking a ump airsoft gun and using that's a shell but they where just too small to use as blow back .
 
Ben,
I put a G2 in my Maadi, but it didn't come with springs. You can have the original trigger though. If you want it, I can bring it to the car shoot if that is soon enough.


Sent from my iPhone using Tapatalk
 
dgrafton said:
Ben,
I put a G2 in my Maadi, but it didn't come with springs. You can have the original trigger though. If you want it, I can bring it to the car shoot if that is soon enough.


Sent from my iPhone using Tapatalk
Click to expand...

That's awesome . Yeah I'm not really rushing this build I need to play it safe and triple check as I go along. I think the hardest part of this will be getting the mag in the right spot and the ejection port in the right spot .

I think I'm gonna buy one of these.
http://www.theflatspot.net/ar-15-receiver-flat.html
So I don't have to deal with making as much stuff.
 
Just put it in my range bag, otherwise I would forget by then. Make sure you remind me at the shoot!

I don't know, I think I would rather do an 80%, but then again, I can't weld.


Sent from my iPhone using Tapatalk
 
I'll have to look to see when I bought it. Some time over the winter, I think. MGI had everything in stock at that point.

That weldable kit is cool. That could be really handy for adapting a grease gun mag to an AR too.
 
asp said:
I'll have to look to see when I bought it. Some time over the winter, I think. MGI had everything in stock at that point.

That weldable kit is cool. That could be really handy for adapting a grease gun mag to an AR too.
Click to expand...

I gave up on them cause every timei asked about parts they never got back to me or told me they had no idea when they'll have more .

A lot cheaper then the two metal lowers and the one plastic lower you can buy.
The metal ones are like 300-400.
The bazooka brothers you need to cut a slot for the mag release. Cnc guns uses its own mag release. The plastic lower uses a mag block .
Some one told me you can use .45 Uzi mags in the 9mm block but I'm not sure.


emesaqyd.jpg

Made a charging handle.
 
One thing to watch out for on any tube gun build is to make sure that a stock bolt will not slide into it. (so in this case a stock M3a1 ) I go with A smaller Tube ID. (or you can do a blocking bar.) (the reason is for possible ATF saying it is convertible to an MG.) For my Swed I don't think 1 part is interchangeable. (not by design but I didn't have one to copy)

I have been using ar firing pins with good success. the trick is to use the inside dimensions of the AR bolt so the pin bottoms out on the shoulder like it does in the AR you want a .040 FP extension. You should check out my SwedK build on WG (In the SMG build all others section. They stickied it )

I made the lower for it from some simple 1/8" flat stock and welded it into the box. and used AR FCG parts.

I have been kicking around doing an m3a1 but I have a few builds in my head that want to get out first LOL.. I was thinking of an airsoft shell and then building the gun into it. (depends on the dimensions. )
 
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I knew about making sure the stock bolt won't drop in etc. But I got a idea for a bolt guide that would not allow any other bolt to be put into it.


I was debating buying one of the pre made firing pin guides that one guy sells on wg. You just drill the bolt out for 1/4 I think and press it in.


One thing I'm trying to figure out is how to keep the rear cap on. But able to remove it.
 
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Well on my K I just went with screw on. My old logan lathe threads fine so I used what I had. (and I wanted to fab the pieces. )
On the original M#a1 it all comes out the front. so you could do it that way too.

I figured You knew about the bolt and preventing a stock one But I wanted to make sure the viewers out there know. LOL

The biggest issue on the bolt fab is the firing pin channel, It is a matter of good setup. and taking your time. I did the last 2 with a HF mini-mill and they came out great. You need Long drills. Honestly if you can drill out the 1/4" hole straight you can do it with the smaller holes. I will keep an eye on the build or PM or email me if you have any questions sometimes it just takes someone else to bounce things off of to figure them out.
 
Yeah I was thinking a inter locking pin setup on the rear . Like push in 1/8 turn and it locks. I figure the front has all the force on it and the rear just needs to hand the bolt moving back .
One thing I'm stumped on is springs and length of movement for recoil. I know it needs to mover enough to clear the mag .

I was thinking if useing one or two ak springs for the bolt.



One thing I learned about denial bars is you have a lot more give and take then a manufacture has .

I was reading about the gory 43 builds and took me awhile to figure that one out.
 
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I am using uzi smg springs for my 2 9mm's, (I figured they did the work to figure it out already LOL) for 45 it will depend on hammer fired or striker. (any build it does) I offset my recoil spring to the top of the bolt with no ill affects. ( for hammer clearance) since your bolt looks wider you will have some extra room for a larger spring. (maybe a m1 garand or m14 op rod spring. ) or go with 2 of them and have the hammer come up between them. If you have AK springs give it a shot. I use neoprene Rod for a buffer and prevent my recoil springs from binding. (mcmaster carr) (when you pull the bolt into recoil you don't want the springs to bind up it will ruin them quickly) so I measure where the spring is collapsed on itself and then add at least 1/2" and cut the buffer to fit.
 
7aqy9umy.jpg

anesa3y5.jpg

atu8ade5.jpg


Started the front trunnion.
I don't have a die holder for a die this big so I threaded some aluminum and made a sleeve.
It's the added to 1 1/4 x18tpi . Sane as a ar barrel nut.
I need to cut off the front half still and when I get the barrel . Bore it to the right I'd and mill the feed ramp.

I'll probably cut off the front numb and bore the front half out to save some weight later.
 
I have the same question as Golddiggie. that and which end is which LOL... As long as the trunnion is welded/bolted into the tube and the threads will be used to hold something else (not dealing with the weight of the bolt slamming into it) this could work but I would have just threaded the trunnion.
 
Unless both pieces are the same metal (aluminum??) I would shy away from welding. You might be able to silver solder it together, but it will still have a weak point. IMO, it would have been better to make it a single piece, threaded via the lathe. I have the tooling to do that on my lathe now, and just need to practice to get good at it.
 
I don't have a single point cutter at work lol . I tried to do it by hand with the die expanded but could get it to cut .... I don't have a die holder big enough. My monkey wrench slipped and cracked me in the ribs.
u4upusyv.jpg


So I just did the threads out of aluminum. Press fit then staked it.
jeja7yte.jpg
also staked in the rear.

It's the same threads as a ar barrel nut so I can use a ar free float tube , quad rail etc.
Or I might just make my own hand guard.

The smooth end in going into the tube /receiver. I'm thinking I'm gonna rivet it like a ak receiver.
 
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