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light weight AK ideas.

1369 Views 26 Replies 11 Participants Last post by  1biggun
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Im working on a build for my young son that will be used for hunting. i am going to use a AR style retractable stock on it to allow him to adjust it as he grows and so i can shoot it as well. I am trying to get the weight down and got to thinking it was a shame to have a some what heavy un needed buffer tube and as well as a rear trunion and reciol spring support and had one of those what if ideas. Why not eleminate the heavy rear trunion comepleatly use the buffer tube to either house the spring or as a area to have a gusde rod slide into coming from the carrier. done right there would be no metal to metal contact and weight reductions could be had. here is a very cobbled mock up. BTW the build will be a 243 or 300 savage. the stock height would higher but this would be good as it will be a optics only build with no FSB or RSB im going to use a galil style gas tube and alloy GB I want this thing as light as possable. Ill add weight for target shooting but remove it for hunting and carry.

If a guide rod was anchored in the carrer and cycled with it most of the top of the carrer could be removed as the spring would run on the rod. or a lloy rod that went into a spring in the buffer could be used. i thing there could be some real weight savings here. the stock mount could be aluminum or even sheet steel welded to the reciver.

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Good idea. Run with it!!!
I don't see why the tube would be used to house the spring, it isn't like the carrier can recoil back into it like it can with the AR bolt carrier, so you don't really gain anything by using it. Also, the weight in the rear trunnion is negligible, especially since it is close to the stock so it won't be noticed nearly as much as weight out on the front of the rifle.

I hate to be one to say "there's no reason to", but I don't really see one. Though putting the stock up that high would completely eliminate muzzle rise, the angles would make it so the rifle might even "jump" down into your support hand...

I think that if you made a bullpup rifle it would feel a lot lighter than a standard rifle. I dunno about anyone else, but rifles with all the weight in the rear "feel" about as heavy as pistols to me. They're a lot easier to hold up too as your shoulder supports more weight, your right hand supports most, and your left doesn't have to do much, which is a really good balance if you're right eye/right hand dominant, puts the weight where your strength is.
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the trunion and spring anchor are fairly heavy. I was thinking of having the spring remain in its original position but anchoring a a guide rod into the piston and cutting away most of the top of the carrier saving more weight.

I could also put a spring in the buffer and just run a light rod from the carrier to the buffer this would put the weight toward the rear and balance the gun out better..

as far as changing muzzel rise I doupt it will really mattter on a semi auto hunting rifle. kids have smaller faces and its hard for them to get there eyes in line with open sigths let alone a scope thats even higher. Hell i shoot my hunting pistol with my head on the dust cover and no stock and its pleanty usable like that. I always need a raised check well on almost all my guns even bolt actions.

when your 10 years old and weigh about 60 pounds every ounce matters if your trying to shoot from a standing positon. the gun will have a break on it for target shooting but will come off for hunting with no ear plugs.

The barrel will have 14" of rifleing and a perminate 2"alloy brake to make it 16" and be fluted in the breach end an be a light sporting weight profile.

I dont even like how heavy the buffer tube is. if its not going to suport a spring or some thng it casn be lighter by drilling it full of holes or fluting it. I was even looking at carbon fiber for a foregrip.

The gun only had to be good for one or two shots in hunting trim and be reasonably accurate out to likely under 70 yards. I considered alloy gas pistons with teflon rings, reciver,gas block, gas tube, the mag will be a three shot alloy cut down G3, I dont know what a AR weighs in in its lightest form but Id like to get it close to that. Throw a RSB, FSB, rear trunion, and a few other parts that can be whittled down and you will see it adds up pretty fast. that and balancing the gun better toward the rear as mentioned above will help.

I could just buy a light weight bolt action but what fun would that be????

Im not a big fan of the stock but its light and adjustable. I could also build a carbon fiber stock save all the weight I saved by oll the mods. LOL
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You want to build a very light hunting rifle from AK bits.

Here's a fairly radical idea - convert it from gas operated semiauto to straight-pull bolt action.

You can dispense with the gas block, gas tube, and gas piston. You might want a thinwall "guide rod", but it might not be necessary when used as a bolt action.

You can carve a *bunch* of weight off the bolt carrier, which would no longer have to handle the load from the gas piston. You could skeletonize the spring retainer and shave even more off the rear trunnion, or fab the parts from aluminum - they only have to take the load from a hand-operated carrier.

Dispense with the upper handguard and use an AMD-65 metal lower handguard. Skeletonize the stock Tabuk-style, or use one of the wire stocks instead of wood.


Remember the old racer's rule: "Don't look for one place to save a pound, look for sixteen places to lose an ounce."
I want to keep it SA but your idea is a good one. I thought about it before and a 10 year old does not need a Semi auto for hunting but for taget practice it will make it nice. I shot my varmint build over 1000 rounds before I made it SA.

I want to be able to colapse the stock as it will not hang a low when packed on a sling and stay outof the weeds and brush, and i can also shoot it my self when extended. Im going to make him pack his own gun or hes not old enough to go.

the new law allows 10 year olds to hunt deer with a adult in arms reach sharing one gun. Ill be hunting with him as well and I need that one gun to useable by myself also.

Im not really sure how much weight can be removed form the bolt carrer and still have it cycle reliably and be safe. I know i can remove a lot of the are that houses the spring as well as shave some off the sides etc. Im just not sure at what pint it will be to light to be able to be controled by a spring and smaller port. Again Im not looking at shooting this thing a lot but its got to be absolutly safe. I dont think the pistion needs to be as heavy either.

Im certain a aluminum GB would work safely and it might wear because the piston hits it. the tube can be alloy as well.

Im not going to get stupid about this but If i can loose a pound then thats a lot for a kid. Im looking for decent short scopes and havent rulled outa red dot but I want him to be able to start shooting long range soon. there are some pretty light scopes out there.

I dont like the AMD hand guard for hunting because the steel gets really cold in a Wisconsin winter. I have had my fingers damm near sticking to My amd pistol and have sworn ill wrap it with cloth or some type of neopran cammo cover every time i take it out. Hell the fore grip can be balsa wood for all I careor even just cloth cammo type wraped around the barrel and tube and leave out the fore grip entirely kids have small hands and the fore grip is to big any way. the pistol grip will need to be wittled down some as well as moved forward slightly to make the trigger more reachable. I want a push button saftey on it as well that he can reach with a finger with ease. The close I get this to like shooting a 10-22 for him the better as he has been shooting those for a while with close supervision.

"Don't look for one place to save a pound, look for sixteen places to lose an ounce."
very very true
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I dont think the pistion needs to be as heavy either.
You could probably take it down to the size of an SKS piston, keep the same diameter piston head, but thin the rod, and make the piston head shorter.

The thing with reducing the BCG weight is that you increase the cyclic rate. Your rear trunnion will get beat harder if you don't reduce the gas port size, and the rifle will be less tolerant of changes in ammo. Also, you might start having trouble with the firing pin having enough inertia to slamfire, what with the higher bolt velocity, so I'd go to a sprung firing pin.

Cool project, I'll have to think about it today about where there is excess weight in the AK system, because lord knows it's there in abundance.
The thing with reducing the BCG weight is that you increase the cyclic rate. Your rear trunnion will get beat harder if you don't reduce the gas port size, and the rifle will be less tolerant of changes in ammo. Also, you might start having trouble with the firing pin having enough inertia to slamfire, what with the higher bolt velocity, so I'd go to a sprung firing pin.
taking out the BCG structure might also weaken the part. I'd love to see the math that the designers did for it's structural strength.

This project is definitely high on cool factor.
The ar stock is a good idea for a lil guy. When my son was 5 he could shoot a car15 easier than a savage cub (both off of a bipod in 22lr and peep sights) because the lop was shorter on the car. Now that he's a little older I have a 6x45mm barreled ar upper that I will lighten up for him for use with the car15 lower for deer season. I'd go with the 243 barrel for starters and you could always swap it out to the 300 when he's older. Since you're going with a short barrel and an aluminum muzzle brake, make the brake like the levang for an ar15. I could send you a rough drawing on how to make your own. That should help with the muzzle blast and flinching. I will be making an aluminum one for the 6x45 when my son shows he can consistantly hit the vitals on a deer target out to 75yds.
I'd love to see the math that the designers did for it's structural strength.
I doubt anyone did any math. They probably fiddled with the carrier/piston mass, gas port size, and gas block length until it worked reliably across the range of variation of the ammunition.


The size of the gas port provides the kick.

The distance from the breech to the port determines when the kick starts.

The length of the piston travel inside the gas block - what, about a quarter inch? - determines how long the kick lasts.

The inertia of the bolt (after unlocking), carrier, and gas piston has to be sufficient to overcome the recoil spring while extracting the old case, while preloading the spring enough to ensure stripping a new cartridge off the magazine and going completely into battery.

Ideally, the bolt carrier does not touch the rear trunnion.


One thing we know for sure is that the AK gas system is amazingly flexible, from 7.62x25 conversions to factory 5.45x39s, .308s, and 7.62x54Rs all on the same basic bits. Then there are the Saiga shotguns with their tappet arrangement...

Heck, just start hacking everything that looks nonessential from the bolt carrier. Worst case, you add some weight back, or order another one and try again. You could also do a lightweight tubular gas piston.

If you go to Armalite's web site at armalite.com, find the technical notes, and look through the files, you'll find several articles on cycling and timing problems with the shorter-barreled ARs. Some of them have pressure and motion graphs that show what happens when you change the location of the gas block. It's not an AK, but the same basic principles apply.
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the gun will be in 243 to start and he will be shooting 55gr stuff for target loads. the GB will be adjustable to cover any range off ammo. I wont do any thing to the bolt to save weight but the carrier can deffinatly be lighter . Im not worried about cycle times unless it affects function. I have to keep the front trunion pretty much as is.
initaly i was going to make the guna folder for easyier carry but I may not. he really needs to get used to a full size rifle at some point.

my biggest concern would be the bolt un locking to soon.
my biggest concern would be the bolt un locking to soon.
I wouldn't worry about that too much, so long as you don't decrease the dwell time [the carrier will move 1/2" or so before the bolt starts unlocking] the bullet should be long gone and pressure decreasing really quickly before the carrier moves back enough to start rotating the bolt. You might be able to lighten it to the point that it starts wrecking brass from the bolt's velocity on extraction though. If the bolt carrier is going too fast I could see it tearing rims, a heavier spring won't help on that end of the receiver either, it'll only slow it down quicker.

Go slow when reducing the weight, up until you get brass damage with the heaviest loads you'll be running, then add a little weight back would be my suggestion.
HMMM I wonder if piston size could help reduce the velocity of a lighter carrier along with a adjustable GB. I have considered running a pistion in the buffer tube with a adjustable air bleed to allow me to reduce cycle rate. much like the sunomi's do.
I have considered running a pistion in the buffer tube with a adjustable air bleed to allow me to reduce cycle rate. much like the sunomi's do.
That'd certainly be a useful plan of attack. But I think you ought to go for the simpler things first.
Rather than re-engineer the AK design into a light-weight youth rifle.... Why not build an AK "clone" around a Mosin-Nagant bolt action in perhaps .44 S&W mag ??? A clone could use the AR collapsable stock, an AK type grip, a scout carbine type scope, and short barrel. To keep the weight down perhaps a built-up aluminum stock/frame resembling an AK.

The .44 S&W Mag is a decent deer round for modest ranges and can be reloaded to appropriate levels for a young shooter.

VD
Just a thought if you can't fab up a button style safety maybe a galil style would work
I have considered running a pistion in the buffer tube with a adjustable air bleed to allow me to reduce cycle rate. much like the sunomi's do.
That would change the speed of the bolt in the rear end of it's travel, which changes the cyclic rate in F/A, but practical cyclic rate [initial bolt velocity] remains unchanged.

Same thing was going on with the M16s in 'nam. They had hotter ammo, and instead of decreasing powder levels, or adding weight to the bolt carrier, they put together a buffer that held the bolt to the rear a little longer to reduce the cyclic rate, it didn't help with the extraction problems because it only affected the rear end of the bolt speed, the time that the bolt's speed didn't matter, the initial bolt speed [the speed of the bolt when it was extracting the case] remained unchanged.

I thought about weight reduction today, and an aluminum receiver came to mind, it doesn't have any locking stresses on it, and when it does eventually come apart it isn't like it'll throw the bolt into your face, it'll just fall apart or jam up really bad.
Maybe use this as an excuse to build a VZ58, they're really light and handy. If you don't mind the x39 chambering they're a really good rifle.
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Rather than re-engineer the AK design into a light-weight youth rifle.... Why not build an AK "clone" around a Mosin-Nagant bolt action in perhaps .44 S&W mag ??? A clone could use the AR collapsable stock, an AK type grip, a scout carbine type scope, and short barrel. To keep the weight down perhaps a built-up aluminum stock/frame resembling an AK.

The .44 S&W Mag is a decent deer round for modest ranges and can be reloaded to appropriate levels for a young shooter.

VD
LOL Im actually colleting parts for a light weight mosin build. I have three m44 barreld reicers with good barrels. Im not sure what Im going to do as far as calibure likely one will be a 7.62x25. there are a lot of options for these.

I like the idea of a colapsable stock light weight bolt action possably with a folder as well it would be a good trunk/travel gun and stow easly I was thing of one for my self done cheap. A 14' light weight barrel with a alloy perminate break and a folding mechinism on wtih a AR style stock would be a damm hady easy to carry cheap to build not have to worry about much indestructiable little rifle.Add a detahable scope and a red dot that swap out and it would be even more versital. The howa Axiom has a AR style stock and a cut down fore end that I like. I was thinking of something like that for a Mosin also. the original 7.62x54 is a excelant deer round and can be loased many differant ways. Im going to put them in a stock and test fire them and take the best one and keep it with a original barrel.

Howa Axiom Standard & Axiom Varminterter Scope Package Rifles

Howa Axiom with Burris 3-12 XTR

I Kind of want to do a AK for him because I have been so invvolved in makinmg them shoot good. Im a little concerend he is to youn for a auto loader but he will be in arms reach and I dont have to even have more than one round in it for that mattel or i can turn the gas off. I am also planing a no holds barred subper build for him wuth switch barrels and all the talent I can throw into into a build for him i was thinking stainless reciver with jewled recesses polished bolt stainless barrel, electrcales nickle plated covers and other parts custom wood stock the whole works, but right now he needs a super light weight not fancy can get scrathed set up. A mosin reciver isint light but It could be wittled down as well especialy in the breach end of the barrel. have pleanty of deer rifles including a few mausers that i can cut a stock down or buy a spare but I just like to do somthing special for him mayb build one tht matches for my self.

I like the 243 because its versitility it can shoot 55 grain bullets at over 4000 FPS ( I wont be loading that hot) and up to 110 grain bullets it will work on praire dogs up to elk if shot placement is good. I have a few 260 remington barrels in a light weight profile as well.


I thought about weight reduction today, and an aluminum receiver came to mind,
Im going to do one at some point possably milled from billet and then use a drop in trigger group/ trigger housing Im nit sure hat the weight savings would be however but it sure would look cool. Ive have a unknown 22mm sagia trunion and it is very light in weight compared to some of the standard AK trunions it wold be a good start and It will use a smaller OD barrel stub as well. Im looking for a 19mm trunion also but havent had much luck. I can always just turn the barrel down except were it is in the trunion also.

the ultimat would be titanium but that out of my leauge. as far as cost and also machining it. I have seen some carbon fiber rifle barrels with steel liners that are super light also.

Carbon's Next Step

Technical
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I vote bullpup style for sure. Uses space move efficiently, and primarily move the weight rearward. AK's are horrible weight balance, and want to fall on their face. Yank that weight back in, and it would less cumbersome to hold ("feel" lighter) more compact, and lighter. All in all easier for smaller folks to use. I think I need one now!
the gun will be in 243 to start and he will be shooting 55gr stuff for target loads. the GB will be adjustable to cover any range off ammo. I wont do any thing to the bolt to save weight but the carrier can deffinatly be lighter . Im not worried about cycle times unless it affects function. I have to keep the front trunion pretty much as is.
initaly i was going to make the guna folder for easyier carry but I may not. he really needs to get used to a full size rifle at some point.

my biggest concern would be the bolt un locking to soon.
I'm just throwing this out there but would milling the bolt carrier like an ak 74 work at weight reduction. If you look at the 74 bolt carrier next to a 47 carrier you can see right away that on the left side of the 74 it has a large lightening cut , you could also mill the FA sear trip on the carrier and there is also room for a lightening cut on the right side of the carrier too , what do you think ?
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