AK magazine

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Ghengisconrad

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So i'm converting an AK to 40 cal. I will make my own magazines, or us UMP40 magazines... my qyuestion is.. does it have to be a banana magazine? or would a strait magazine work do you suppose?
 
Another way to phrase the question may be... "why are AK magazines banana?" would a straight one not work?
 
Most box magazines are curved to follow the curve that the rounds make as they rest against one another. So the curve of the magazine is a function of the taper of the cartridge.

Examples: 5.56mm cartridges are fairly straight-walled so their mags are not heavily curved -- in fact the 20 rd mags are straight. 7.62x39 cartridges are fairly heavily tapered, so AK magazines have a strong curve.

Most handgun cartridges have very little taper and so work well in straight box magazines. .40 S&W is no exception. Putting it in a curved magazine would be unnecessary and might make it feed less reliably.

The bigger concern is the relationship between the lips of the magazine and the feed ramp and chamber. Placing a .40 S&W cartridge (in the feed lips of your magazine) "somewhere" in an AK's mag well, allowing the bolt to strip the cartridge, and expecting it to push-feed naturally into the chamber may be overly optimistic. Gonna need some engineering to figure out when/where the mag should release the round and how to channel it into the chamber.

-Sam
 
As Sam1911 said. Also, the curve seems to make the weapon more easy to use. A straight magazine would be noticably longer and less easy to use, especially prone.

The follow on question is why are you converting the weapon? 7.62x39 will outperform the .40 S&W in every sense, and it is actually cheaper to shoot. The only drawback would be overpenetration in urban environments. But it is more effective for self defense and hunting and against armor and penetration.

Why go through the cost and effort to convert. Just get a weapon that is a .40 carbine. There are many on the market. I believe Keltec and Hipoint offer .40 carbines.
 
why go through the effort? I dunno... I like to have a unique item, and also like to have a project... AKs are indestructable... the action on an AK is my wet-dream...

What I REALLY wanna do, is take an AK74 (the boltface is 10mm, and i would be able to shave off .35 mm around to fit a .40 S&W) use an UMP magazine, move the placement of the magazine as far back as possible, put the trigger as close as possible to the front of the magazine (maybe make a grip out of the magwell), put a forgrip, house the whole thing in some polycarbonate furniture (maybe resemballing a UMP?..), put a buttstock at the end of it, and call it a 'rifle' that shoots .40...

I know this isn't impossible... People convert their AKs to 9mm all the time, but use a blowback function, I want to keep the piston for maximum reliability...

why? I dunno... because I already own a glock .40, and it would make my ammo stockpile more conscise... because I love AKs... and again... a project that will gain me a sweet totally customized AK that has the appearance of a UMP and is MINE and only MINE is fun to fantasize. If it takes years to get the details right, thats fine too! In the end, what i'll have is MY creation, and will be worth more to me than 10 off the shelf hi-point whatevers...

I don't need a new excuse to chew through my ammo, i need a new excuse to increase my ammo stockpile. I am a collector, not a shooter... sorry.
 
AK Conversion

So i'm converting an AK to 40 cal. I will make my own magazines, or us UMP40 magazines... my qyuestion is.. does it have to be a banana magazine? or would a strait magazine work do you suppose?
 
Straight magazine would be fine, the "banana mag" comes from the very steep tapered case walls of 7.62x39 and somewhat 5.45, the bullets just fill that way.
 
I know this isn't impossible... People convert their AKs to 9mm all the time, but use a blowback function, I want to keep the piston for maximum reliability...
Click to expand...
The direct blowback is likely the most reliable action type ever designed (though recoil operated is probably on par)...especially for pistol cartridges. 99% of all pistols operate in this manner and many are extremely reliable (some rival the legendary AK WRT reliability), there are only a few gas operated pistols that I am aware of and most have/do exhibit(ed) mediocre performance and reliability (and some have very poor performance), they are also much more difficult to clean and more finicky about the ammunition type, weight, charge, et cetera; besides you would have to completely redesign the gas operation of the AK to accommodate the weaker round's performance. Not worth it IMO.

:)
 
See above.

A straight blowback in something that size for .40 would be much easier, and be very gentle. A gas piston in something like that would take a lot more work, and even be less reliable--you would need to completely rebuild the gas system to make it work at all, and in a rifle I doubt you'd have much to spare.
 
yeah, but specifics of a .40, the magazine can feed straight (i guess...), and I'm hoping I can move the magazine spot itself back (seeing as how i'm making my own receiver anyways), and with a straight magazine, I could move the trigger to right up against the well, so I can use the magwell as a grip, and have an apropriately placed forgrip...

I'm thinking I'll mod the mags to have fairly large bottoms, or even extend teh magwell 'grip' to cover the whole mag... why?

http://www.outdoorbunker.com/ProductDetails.asp?ProductCode=(MAK-T-POD-BK-OD-T-)

thats why...

Prone power, with a very tight size...
 
Maverick223 said:
The direct blowback is likely the most reliable action type ever designed (though recoil operated is probably on par)...especially for pistol cartridges. 99% of all pistols operate in this manner and many are extremely reliable (some rival the legendary AK WRT reliability), there are only a few gas operated pistols that I am aware of and most have/do exhibit(ed) mediocre performance and reliability (and some have very poor performance), they are also much more difficult to clean and more finicky about the ammunition type, weight, charge, et cetera; besides you would have to completely redesign the gas operation of the AK to accommodate the weaker round's performance. Not worth it IMO.

:)
Click to expand...
The direct blowback is likely the most reliable action type ever designed (though recoil operated is probably on par)...especially for pistol cartridges. 99% of all pistols operate in this manner and many are extremely reliable (some rival the legendary AK WRT reliability), there are only a few gas operated pistols that I am aware of and most have/do exhibit(ed) mediocre performance and reliability (and some have very poor performance), they are also much more difficult to clean and more finicky about the ammunition type, weight, charge, et cetera; besides you would have to completely redesign the gas operation of the AK to accommodate the weaker round's performance. Not worth it IMO.
Click to expand...


hrm.... I work at a place where we have many people knowlegable on guns and stuff, and I will be the first to admit I am a NOVICE; but I prefer to jump in the deep end first and make my way back to the shallow end.

To the person I am working with, I mentioned blowback specs, and he said that they are less reliable. He is no gunsmith, but knows alot more than I do...

I am content to fantasize and hammer the details in my mind out for now, just learning and studying... I have a book on how to make your own 9mm blowbAK from scratch... its a little dense (or sparse, I can't tell) in some parts, but what I want to do is buy an AK and modify it, to ensure legality etc...

right now I'm thinking the project would be

Step one: buy an AK74

Step two: buy Hi-point 40 cal barrel and UMP mag

Step three: modify boltface to deal with .40 cal bullets (shave .35mm around)

Step four: make new receiver with mag far far back, and trigger where my hand feels conmortable, as well as a latch, lip, and magwell system...(???)

Step Five: Make spring to correct tension

Step Six: ??????????? not sure what I'll have to do to put it all together... and I'm sure I'm missing things.

Step Seven: the fun part; furniture.

Step Eight: mission accomplished.
 
THE PROJECT: Ignore if you are cranky

redirected from http://www.thehighroad.org/showthread.php?t=493850

Okay, so the topic has changed. This is a new thread.

I don't want to discuss if its a good idea or not, I just want to figure out how to make it work. If you don't want to help, then don't. This is really a mental excerscise at this point, but I freakin' love it! All help would be greatly appreciated.

I'm going to build a bullpup AK in .40. I guess blowback is considered the best way to do this?

Here is what I figure I'll have to do.

Step one: buy an AK74

Step two: buy Hi-point 40 cal barrel and UMP mag

Step three: modify boltface to deal with .40 cal bullets (shave .35mm around)

Step four: make new receiver with mag far far back, and trigger where my hand feels conmortable, as well as a latch, lip, and magwell system...(???)

Step Five: Make spring to correct tension

Step Six: ??????????? not sure what I'll have to do to put it all together... and I'm sure I'm missing things.

Step Seven: the fun part; furniture.

Step Eight: mission accomplished.
--------------------------------------------

All help greatly appreciated. :evil: Links to appropriate information also helpful... I have Googled to the best of my abilities at this point...

Thanks for the input if any!
 
I guess blowback is considered the best way to do this?
Click to expand...
Yep, not elegant, nor does it conform to the original AK design (...but what else does?); but it works and does so quite well, particularly with pistol cartridges.

buy Hi-point 40 cal barrel and UMP mag
Click to expand...
May want to look into whether a .45cal grease-gun mag can be made to work with .40S&W, as it would be much less expensive (though it isn't as if the build will be cheap, so it may not be an issue).

(shave .35mm around)
Click to expand...
Will that still provide enough strength? I suspect it will but don't know for sure as I haven't a AK-74 to measure for width. Either way it is something to consider.

make new receiver with mag far far back
Click to expand...
Can't be too far back because there has to be room for the bolt and action spring, which is rather large in the AK family of rifles (the AR-18 family is much better suited to bullpuping IMO). Also, if I read correctly you wanted to use the magazine for the grip, this may be uncomfortable and unergonomic. Also this probably wouldn't be ideal because the grip would need to be too far back, thus having too short of pull...or equally bad having it too far forward and not making the rifle as short as possible (that is the point of a bullpup after all), thus removing aft weight making the rifle forward heavy and increase time of target acquisition (will point slower).

and I'm sure I'm missing things.
Click to expand...
The complicated bit is the trigger linkage (to achieve a good, crisp break).

the fun part; furniture.
Click to expand...
That part is easy...there is very little furniture on a bullpup...a butt-pad and a foregrip or vertical grip.

Good luck, Mav. :)
 
MAC-10...add bull pup furniture, your done, cheap, easy, inexpensive.

AK74, welder, grinder, cutting torch....dynamite! yikes man....!

Oh, and...45cal. grease gun mags wont do the 40S&W thing, we tried this for a cheap alternative to mags for an Olympic 40S&W AR.
 
I'll suggest that you'll want the mag as far forward as possible, in relation to the breech. You want the cartridge to have a pretty short path into the chamber. It's going to be hard enough figuring out how to funnel a .40 S&W up into the chamber anyway, having it pop free of the mag feed lips 1.5" or 2" back from there is going to be a recipe for failure. The cartridge may go any which way BUT into the chamber.

Rifles are usually designed so that the magazine doesn't release a round until the nose of the bullet is all but in the mouth of the chamber. (Watch this: http://www.youtube.com/watch?v=q7d8wvEKoy0, right around 58 seconds) It's a push-feed, not "controlled round feed" like a Mauser bolt action. The feed ramps, mag lips, and chamber mouth, and the relative positions of each, all have to work together with the shape of the cartridge being fed, to make sure it gets where it's supposed to, reliably. If you substitute a short, cylindrical (not tapered/conical) cartridge, and then give it lots of room to "play," some of those rounds may be backwards by the time the bolt tries to smash them into the chamber.

Obviously, there have been a lot of sub guns that were built to get around these issues. I'd look at how these things are related in an UZI or MAC.

Good luck.

-Sam
 
Oh, and...45cal. grease gun mags wont do the 40S&W thing, we tried this for a cheap alternative to mags for an Olympic 40S&W AR.
Click to expand...
Oh well...but they can be made to feed .45ACP pretty well. :D

FWIW, I really like Sam's Uzi idea, it is reliable and the bolt design (riding over the bolt) should lend itself to bullpuping fairly well. Also it shouldn't be that hard to chamber in .40S&W as there is already 9mmParabellum and .45ACP versions. I am not a big fan of the Mac-10 OTOH, but to each their own.

:)
 
The input is GREAT guys!!! I'm a little hung over this morning to fully digest, but I'de like to maybe clarify some things.

Look here: http://www.ableammo.com/catalog/product_info.php?products_id=98864

Now thats the length I want, but not the ergonomics. Thats why I do all this. I want from the receiver down to look like

http://world.guns.ru/smg/hk_ump40.jpg

so the fantasy is attached... maybe move the trigger and grip back just an inch or inch and a half...

and where the mag goes... not sure....

I mean seriously.... if i could, i would just buy a sub machine gun, but even if it was a select fire only, it would still be a SBR.

I like this legal franken-sub rifle.

This gun aint going to be logical in a cost-benifit kinda way, but its going to be

a. beutiful

b. LEGAL

c. extremely weildy

Maybe think of the project his way "how do I build a UMP 40 clone legally"
impossible is nothing. With enough custom parts its can be done. I think I can make an awesome piece of fantasy for under a grand...
 
thanks for the encouragement... I enjoy learning the logistics more than anything. I'll keep bouncing the idea around...
 
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