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MY SONS SWITCH BARREL AK BUILD IDEAS

16K views 114 replies 24 participants last post by  twa2471 
#1 ·
Im starting a build for my son and he got a box of AK parts and barrels and stuff for Xmas. it will be a 243 0r 260 remington loaded to light pressure.
Its going to be a light weight sporter and I want it as light as i can make it besides the heavy m70 trunion. this will be a outside the box build over the next year were he helps build it. He is 9 and will be able to shoot deer next season. I plan on letting him do as much on it as he can including some of the machine work that way he will know whats going on and how it all works and get some Shop time with Dad. It will have gas shut off as well and he will be shooting this as a non semi auto at first. Baby steps here.

Hes pretty sharp and noticed I had three barrels in the box, a 243, Win 260 Remington and 308 WIn there all model 700 take offs. he asked why there were three barels and I told him we were only going to use one but I hadent decided what one and that id keep the other two. Well hes not one to give stuff back that he just got, so he says way not use them all and just change them.

I have thought of several differant switch barrel assembly set up's in the past but they all required seperate trunions on a screw build. So got to thinking about a threaded barrel set up.


it looks like a 1"-12 thread can be used on the 23mm trunion if the bore is opend up to .9219"
that is .016 more than the factory bore. thats not much metal to get things right with with the boring bar if it dont cut good on the first try. the Yugo bore is not interupted like other trunions were there are hollow spots between the barrel and the trunion. aside from the barrel pin there is no interuptions. I really wish I had a virgin trunion to work with. the RSB will need to be removable or able to slide forward or you will not be able to unscrew the barrel. I was thinking of useing a barrel nut like the savage bolt actions and all barrels will need to be timed but that should not be a issue as once there head spaced correctly they will always be reinstalled in the same place every time.

I have seen were a guy threaded a 410 Saiga in conversion to a 500 S&W so I know it can be done. I think the model 70 Win uses a 1" thread .

this build is going to have a custom Aluminum RSB and likely a GB so I a dont have to worry about traditional looks in fact the less it looks like a AK the better for this build. people get nervious with kids shooting AK,s for some reason LOL.

I was even thinking with a differant bolt I could even do a 410 SG barrel for it.
 
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#58 ·
Why dont you make 3 barrel units with 3 bolts. (barrel, FS, GB, RSB, and Rear Trunnion) then you could do a screw build, and undo 3 screw on each side, switch the barrel unit, and bolt out and your on to the next cal.
COST Im doing at least 15 barrels for this set up. I will start out with 22-250, 243, 260 rem and 300 savage initaly. the rest is just for the hell of it.

I already have several builds that are screw builds that I swap out entire barrel assemblys. trunions are not cheap and those shallow threads are only good for so many assemplys. the cost of RSB trunions and GB alone would kill it for me. The m70 trunion is much better however except for the screw by the mag well.

the way im doing it I will only need to unscrew the barrel and each barrel will only need a GB and even that could be a clamp on and swap out. I wont need a seperate RSB and I wont need a FSB on any of these as it will be a scoped build. I may however do a barrel with a FSB for hunting in the rain or heavy snow. On my set up the RSB/optic rail will stay with the reciver and the scope can even be charted for each barrle so it wont even require sight in (hopefuly)

I just picked up a 6mm-284 reamer and 10 standard proflile 243 WIN barrels so there is going to be a bunch of differant 6mm caliburs to try.

I expect to have a 223 bolt, x39 bolt and a opened up 308 WIn diamiter bolt.

Im not sure if my sons first build is going to be as fancy as I originaly planed weight is a huge factor so this may be a more traditional build with alloy parts and super light furniture and a pencil thin 14" barrel and a very light perminate 2" muzzle break. 10 year olds are not very big so holding up a long rifle can be tough. I really only expect him to be able to carry it to a tree staand and be able to shot under 70 yards hope full much less initaly. Im going to have him practice with a light loaded 22-250 and then swith to a 300 savage for hunting. reciol is not noticed as much when shooting game.

Im thinking a full on custom high end no holds barred swicth barrel for him and me down the road. time is getting to short to reinvent the wheel. I need to get him shooting a high power rifle like he will hunt with ASAP. the season is in october.

I orderd metal for the reciver today. a normal reciver will not work as I dont want mag well bulges as Im using G3 nmages and there to wide for the bulges to clear.
 
#59 ·
well I have about $150 worth of 4130 steel flat DOM tubing, sold round steel and aluminum as well a stainless steel coming Id better build something soon.

Ill be building .060 recivers from sheet stock with no mag well demples and plan on doing custom gas tube an RSB
 
#61 ·
Doing it the old-fashioned way!

If you use the .060 stock, you don't have to dink around with axis pin dimples or stepped top rails.

Are you going to extend the RSB to the back, or splice together a longer top cover?
 
#63 ·
Why do a .300 savage? You could do a .308 and load light for it at first, then when your son gets a bit bigger he can use the higher power ammo if he wants. Or does the savage round have the same rim size as one of the other rounds you're doing, as that'd make sense then you don't gotta make another bolt.
Im doing 300 savage because if a factory load was accidentaly fired it will still be a pretty safe pressure for a two lug AK trunion. 308 is over 60,000 psi SAMMI spec were the 300 savage is under 50,000. The 300 savage will do any thing the 308 can in the real world and it is a few grains less on the powder capacity so I can load rounds with maximised powder to case capicity and get good accuracy. I fear that it would be to easy for one of my hot 308 loads to find its way into his gun. the 308 wont chamber in a 300 barrel.

I will be using a amd length tube but the GB will be custom or a L1A1 that will be adjustable and also shot off the gas completly. but I am going with keeping the barrel weight down and as far back as possable. My son is pretty small so this thing needs to be as light as possable. he will likely be shooting from a stand at 50 yards or less so the barrel can be pretty short. Im not looking for maximum accuracy here just pleanty of knock down power. IMOO the 7.62x39 is just a little to much on the light side and could use a extra 200-300 FPS and the 300 has exactly that or more. I am actuallu considering trying a 14" barrel with a perminate break. He will deffinatly need a break when practicing. I likely will put some lead shot in the stock for practice as well or even use a lead slead. I have untill october to get him up to speed.

Im throwing together a 243 press in barrel build on a AMD 63 with fixed stock with normal saftey and stuff just to get all the bugs worked out of the G3 mag well and feeding ect. Im not sure i will have time to get the really custom gun for him done and it will be heavier as well. I have several really thin profile model 7 remington barrels one is in 260 remington in stainless and is really light.


Ill be reloading 99% of the ammo fired in this gun . since I have the reamers im considering lengthening the neck and throat of the chamber so 7.62x51 brass can be formed with out havinng to trim the necks. factory 300 ammo would still fire but I can use cheaper surpluss brass that is thicker and not have to cut a 1/16" off each case.

Doing it the old-fashioned way!

If you use the .060 stock, you don't have to dink around with axis pin dimples or stepped top rails.

Are you going to extend the RSB to the back, or splice together a longer top cover?
yes and no on the old fasion way. yes in that Im using flat sheet metal no in that the gun will have a push button or thumb lever saftey, no mag demples, G3 type mag well, lower rails that will run down the entire reciver and add reinforcement, taperd to tight fit on lock up upper rails. custom sized pin holes that will use custom pins. possably a completly removable trigger group and guard ect. The standard flat would need to amn y mods to make work. better to start from scratch. I might taper the front like a Galil and the rear as well to allow more material around the web of a thumbhole stock.

the flat pictured is .045 but I have some .060 flats just like it.

I really dont need to move the trunion ahead if I loose the factory type mag latch and go with a G3 type well as the AK latch takes up close to 3/4" that a G3 wont need.
I just made flats long for the hell of it so a can do a traditional mag latch build. G3 mags can be had for under a $1 so welding ligs on thim wont hurt any thing.

as far as t he dust cover I have a few ideas. the RSB can be easly moved back but Im think more of a completly custom RSB that will extend way back and allow a rail to mounted directly on top of it. then cutting almost half the cover off. you can go quite a ways back with a RSB and still get the carrier in. This would end all the BS about trying to get a decent scope mount on a AK. it can be made in aluminum as well and ighten the gun up considerably. on the switch barrel it will ataach to the trunion and stay with the reciver when the barrel is removes so I only need one RSB not 15. i have 90% of it figured out not sure if it will go on his first gun. he may get a super light 243 for opening day instead and that will give me more time and hopefully more money to spend on the switch barrel design and custom touches. I have some really cool ides for the mag release and safety. stay tuned.

Im considering building and selling a G3 mag well that would rivet or bolt in to a standard reciver with light mods possably with 308 length and ejector positon rails as well as possably bent blank reciver shells if there is any interest. maybe even barrels trunion and head spaced bolt combos. Im still thinking about it all. Need to get the gun done first. the 243 im doing will be more traditional but with a few light tweaks.

here is some pics of a 300 savage with a 185 grain rn next to a wolf 308. as you can see the savage gives up very little and at one time was in the top 4 for Elk in the US in the early days. imagine that round with a longer neck and the Savage might even out do the 308 :) some mock ups of a G3 mag well also.
 

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#65 ·
I am actually considering trying a 14" barrel with a permanent break. He will definitely need a break when practicing.
What I'd do is a 16" if you're considering going that short already, and drill out some ports in the barrel if you really want a brake. I'll draw a simple picture for you to illustrate my idea.



Making the barrel as short as you might and sticking a brake on it won't reduce weight much, but it will reduce "free" velocity. Though as with everything OTI it is just a suggestion.

ETA: looking at my picture again it seems the counterbore/welded on brake would also reduce possible crown damage.
 
#64 ·
a max load listed in my Win loading gide for the 300 SAV is a 150 grain bullet with 42 GR of 748 powder doing 2600 FPS with only 41,000 CUP. that is a 25 grain heavier bullet going at least 300 FPS faster at just slighty over he bolt thrust of a x39 round. that is a MAX load using WIN componets and likely about identical to a factory load. the 308 FS in the same book makes 250 FPS more BUT at 7,000 CUP more pressure. Im sure if the pressures were rasied in the 300 sav It would only be a about 50-100 FPS slower.

IM MORE EXCITED ABOUT THE 243 IM BUILDING THAT WILL SEND 55 GRAIN VMAX BULLETS DOWN RANGE AT CLOSE TO 4000 fps AND THEN CAN ALSO SHOOT 105 GR A MAX AT AROUND 28,000 FPS. THIS WILL BE A FUN GUN FOR LOTS OF DIFFERANT APPLICATIONS.. PDOGS TO DEER. :) THE BARREL IS DONE FOR A PRESS BUILD.

a 308 can be loaded using 307 Win recipes (they use the same dies) and be reasonably safe IMOO. 307 max loas with a 150 grain bullet will do 2305 FPS with only 34,000 CUP and be well under a x39 bolt hrust and still send a 150 down the pipe at the same speed as a X39.

a good 300 sav kids load is a 110GR bullet doing 3000 FPS ( 700 fps fater than a x39 BTW) and only making 41,000 cup. that will give super flat trajectorys out to 300 yards and 110 grain will still be pleanty on a deer at those speeds, ask any 243 hunter.

These are all Max loads out of a winchester book BTW and likely will need to be started at a reduced load. DONT USE ANY OF THIS INFO LOOK IT UP YOUR SELF. DONT USE ANY LOAD YOU SEE ON THE NET ULESS ITS FROM A POWDER COMPANY OR OTHER REPTUABLE SOURCE.
 
#66 ·
I considerd doing a magna port style brake, I have a dozen AMD brakes just figured Id use them. there heavy but they work well and look decent I was going to add a insert t.

The 30 cal Kreiger barrel I have that is stainless and fluted has a very nice small OD break installed on it. Im saving that barrel for the perfect build.

I have a tool that I designed that allows me to easly index the groves so I would not have to counter bore but i have the reamer if i need to. The kid is pretty small so I was thinking the short barrel would help him keep from dragging it on the ground.

I can do a barrel really cheap since i have the reamer in 300SAV so making a bigger one down the road is not a biggie. On the screw build they will change out in about 2 minutes.

I was entertaining the idea of aluminum for a break. seems like I have seen them used on some thing. Im not looking for long life here. I hoping for one shot from a tree stand LOL going light adds recoil so its a big balancing act for a 9 year old. I will have a 22-250 barrel ready if recoil is to much as well as a 243 and 260 barrel im sure something will work.

I was looking at long eye reliefs scopes for it last weekend the Nikon omega is really nice and has 5" of relieaf its made for a black powder rifle 3x9 I think not cheap but not stupid prices. Im thinking of spring loaded stocks or possably a air spring in a tube. recoil is going to be a big issue for him I already know it. Ill have him shooting super light 30-06 loads ( 6 graind red dot) this weekend.

Im not to concened about velocity loss to much as this will be designed for a 50 yard shot and even with a 14" barrel it will out do a x39 with a 18' barrel.

There are some really cool carbon fiber tension barrel out there that are really light but there way to much money for this project.

Its all up in the air at this point.
 
#67 ·
Im thinking of spring loaded stocks or possably a air spring in a tube. recoil is going to be a big issue for him I already know it. Ill have him shooting super light 30-06 loads ( 6 graind red dot) this weekend.
Recoil was a really big issue for me, probably because I went straight for the "big" calibers [second range trip with firearms ever]. Start him with the proposed .22-250 barrel and move up to the .243 when he feels comfortable, then up from there. Even after I realized recoil didn't hurt I still had my flinch, from the momentary "what the hell's going on, loud noise, I'm not in control" impulse, Starting with a lighter recoiling round probably would have lessened it, because I would have felt more in control...
Im not to concened about velocity loss to much as this will be designed for a 50 yard shot and even with a 14" barrel it will out do a x39 with a 18' barrel.
:rofl: 18 foot barrel, even if it's a typo it's still good.:biggrin:
 
#68 ·
18 foot barrel, even if it's a typo it's still good.
thats just for the pistol LOL OOPs.

the 243 I profiled last night is 18" and the same profile as a AMDS 63 but longer.

I likley throw a short stock on my 223 18 pound varmint build its deadly accurate and the big scope and light trigger will get his confidence up. I sarted out with a 30-06 with no pad when I was 12 and it used to beat the crap out of me. scope cut my eye damm near every time I shot a buck. Im going big on the port so light loads will cycle as well as being able to shut it off for the super light 6GR reddot bunny busters. I love shooting those things. I plan on having him shoot one shot at a time to get him used to loading it. He can barely pull the action open so a big round charging handel might help. Hes not very big but he is really smart so he will figure it out. he shoots the 22lr pretty well.

im setting up the screw barrel with no bullet guide so I can also use x39 length rounds with a spacer for the mags and a differant bolt. I have a 17-223 reamer and a couple barrels that will make a fun kids round and it shoots 4000+ fps so you just put the + on the target and fire out to 300 yards and get hits.

I can dial the 243 down a lot with 55 grain bullets and lighter loads. there are some pretty good youth loads on the hodgen website using slow powders. I dont shoot under 55 grain even with my 223. i suspose a 22-250 dialed down with 40 grainers would be even lighter. I cant wait until hes old enough to take praire dog hunting were he shoot a 1000 rounds :)
 
#69 ·
1Biggun, if you're putting a muzzle brake on your sons barrel to bring it up to 16", consider making a Levang type comp. They work pretty well to direct the muzzle blast down range on my 223 coyote gun. For a youngster it would be nice not to have all the muzzle blast frpm that short of a barrel which can make some people start flinching. I also don't think a custom levang style brake would be that hard to make either.
 
#71 ·
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1Biggun, if you're putting a muzzle brake on your sons barrel to bring it up to 16", consider making a Levang type comp. They work pretty well to direct the muzzle blast down range on my 223 coyote gun. For a youngster it would be nice not to have all the muzzle blast frpm that short of a barrel which can make some people start flinching. I also don't think a custom levang style brake would be that hard to make either.
Ill check it out. he will have plugs and muffs on for target but hunting is a whole differant matter and running a break then can cause issues.
 
#73 ·
The levang is nothing to look at, but they bring my 223 blast down to less than my 17hmr. I got one because I'm already deaf enough and you don't always have time to get your ear muffs/plugs on it time while hunting. I'm using it on a 223 ar15 so I don't thing those things kick hard enough to notice a difference.
 
#74 ·
I spent a good part of yesterday looking into various threads and avalaible taps and such an i decided to go with a 16 thread. there is some 14 threadtaps out there but I like the idea of using original threads on the winchester barrels and others. according to my sources a 15/16-32 would give 80% thread engagememnt and a 15/16-27 would give 66% on a 23mm trunion that was .905".

here is a sight with a really handy tap drill size calculator. if 22 mm trunions were more plentifal then there would be some other options as well.


Tap Drill Sizes

Im trying to stay with non metric sizes as I cant cut many metric threads.
 
#76 ·
So how is it coming along? Any pics of current configuration?

Did you see the quick disconnect barrel system from US Palm? That would be a perfect setup to use for a quick change barrel setup, so you could shoot multiple calibers.
 
#77 ·
The US palm thread Is what got me to find this thread and Bump it up. I like there set up but i dont think it will stay tight like Id want on a target type build. Id like to have one of there trunons to play with. If some one is going to all the trouple to make a special trunion why not make it around a 3 lug bolt give us what we want a AK more sutiable to high power loads. take there trunion add a 3 lug bolt sell it in a 308 with a couple of barrels to go with it. a 22-250 and 243 or other. add a extra bolt and mag addapeter and you could also have x39, 223, pistol caliburs. I Like what they did but just making it a brake doawn dont add a lot to the usefulness of the gun with out other barrels. how small you need a AK to store or transport it????

as far as my project its still sitting here. ive collected a few taps and some tooling but havent done much. i want to do it right. yugo trunions are not cheap any more.

I bored the trunion to a larger size to thread it and then stared thinking of going to a differant thread size. I had to pull the trunion out of the mill and lost my set up and I havent got back at it yet. Im debating on what thread to go with. I am still collecting barrels. its about 3 degrees in the shop right now and Im swamped with other work.
I also wanted to get a virgin trunion with no pin hole as well but money has been tight for stuff like that. im working on a 243 AK currently and trying to get the bugs out of my G3 mag set up on a nonmachined trunion. If and when I get it dialed in Ill use the set up on the switch barrel build.

I also want to get my 444????? wild cat up and running as well as it will be one of the caliburs that ill be doing for the switch barrel build.

I ended up building my son a light weight x39 with a ar stock and canterlever scope to hunt with for now. m hoping to perfect my 308win type conversins a little better before building him that one special gun for him. Im sort of looking for a super Vepr 308 full length wood stock for this build as well and so far I havent seen any for sale.
 
#78 ·
WELL ITS BEEN OVER A YEAR AN I HAVE GOT NO WERE .

IM TALKING TO A MEMBER WHO CAN MAYBE HELP ME ON THE THREADING AN I BOUGHT A VIRGIN M70 TRUNION THE DAY THE SCHOOL SHOOTING TOOOK PLACE.

THIS IS GOING TO GET BUILT JUST NOT SURE EXACTLY WHT THE PLAN IS YET.
I NEEDED TO REREAD AL I HAD WROTE TO EVEN REMEAMBER WERE IM AT.

I JUST KNOW THAT IF THERE ARE GUN LAWS PASSED THAT IF YOU WANT A DIFFERNAT CALIBRE AK IN THE FUTURE YOU WILL NEED TO WORK WITH THE RECVIERS YOU HAVE AS THERE IS NO GURANTEE THAT WE WILL BE ALLOWED NEW ONES.

I WANT TO BE ABLE TO HAVE MY 6MM BR VARIANT TO BE ABLE HAVE A REALLY HEAVY BARREL AN SCREW INTO A RECVIER SO IM GOING TO BE RESTARTING ON THIS BUILD .

ANY WAY BUMPING IT UP SO I CAN HAVE A MEAMBER FIND IT .
 
#79 ·
Took a while to read back through the thread. There was a question on the barrel threads being thick enough on the heavier bulged trunions to handle 60k psi. Ruger 77 (and some push feed Winchesters) uses 1"-16tpi (minor diameter .919") which isn't much off of where a 23mm trunion is, or 1"-14tpi (minor .907"). I haven't heard of ruger 77's or push feed winchesters failing.
 
#80 ·
I haven't heard of ruger 77's or push feed winchesters failing.


NO AN I HAVE SEENTHE BARREL SPLIT FROM OBSTRUCTED BORE ON A RUGGER M77 AN THE BARREL WAS IN BLACE AN THE RECVIER WAS STILL USABLE . LIKELY SAW 120,000 PSI

AN SOME OF THOSE PUSH FEEDS IN 22-250 LIKELY SEE CLOSE TO 70,000 psi WITH HAND LOADS . SAMMI IS 65,000 ON THAT ROUND. IM NOT GOING TO LOAD PAST 50,000 OR AROUND SMALL RING MAUSER PRESSURES .

LOTS OF LEVER ACTIONS WITH EVEN SMALLER ODS THAN THAT AN SHOOT OVER 50,000 PSI ON A .470 CASE HEAD . .

I FOUND ALL MY TAPS AN STUFF TODAY FOR THIS PROJECT .

WILLIE IS RUNNING A 500 S&W ON A TREADED 410 SAIGA TRUNION THAT I THINK IS 22 MM?? WILLIE YOU THERE.

A VIRGIN RPK TRUNION WITH NO BARREL PIN HOLE AN CUT OUTS FOR RIVETS HAS MORE SURFACE AREA THAN A LARGE RING MAUSER . THE TREADABLE ARE IS ABOUT
.735" LONG . A 12 TPI LARGE RING MAUSER THREAD IS ONLY ABOUT .640 LONG

BTW M70,S YUGO RPKS OR ANY OTHER ak THAT HAS THE SAME RIVET PATTERN DOES NOT HAVE RIVET CUTS INTHE BORE AREA. THEY WOULD BE MY FIRST CHOICE

SMALL RING MAUSER IS ALSO 12 TPI BUT SMALLER

ALSO DONT FOGET THERE ARE MILLIONS OF MILLED AKS WITH A THREADED BARREL OF ??

MY MAIN CONCERN IS GETTING THE HARDEND TRUNION THREADED .
THE YUGOS SEEM HARDER THAN A ROMMY OR OTHER I HAD A HELL OF A TIME GETTING ONE READY FOR A SCREW BUILD LAST WEEK I WNET THROUGH 3 TAPS BUT GOT IT DONE ANTHE HOLES WERE LARGER THAN WHAT THE TRHREAD CALLS FOR .
I DID BORE ONE WITH A CARBIDE CUTTER HOW EVER .

THIS PROJECT WILL HAPPEN
 
#81 ·
1biggun, I was curious as to how much the threads would be effected on a remington barrel if it was rethreaded to 1"-14tpi since 1-14 taps and dies are about half of what 1-16 ones are. I chucked up a section of 1.25" 4150, took a skim cut and threaded to .009" deep with the lathe set at 16tpi which would be about what is left on the remington barrel turned to 1". Then changed the threads to 1-14 and started over. This was just a quick test, so I didn't grind a new bit and just used an indexible bit which had a slight radius to the tip. You wouldn't normally use one for threading since it would leave the bottem of the "V" rounded....which it did and you can see if you click on the pic. But, we're wondering about the tops of the threads, so it works just fine. Since the tip is wider it would also increase the criss cross areas. If you look real close you can see where the old threads crossed the new. Cut with a proper bit, I don't think it's an issue.
 

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#82 ·
I could live with that.

also about 1/2 of the threads in the trunion will be fresh an a lot of the originals well be removed an un used were its through the trunion.

I got the 1-14 tap also to clean up the trunion if needed.

I wish 1 1/16-16 dies were cheap.
 
#83 ·
Thats what I thought. it kind of just looked like there were a couple of light dings in the threads similar to a remington barrel I've had kicking around for a while. Not a big deal especially since it's not a ding, the metal is just gone. 1-14 has a minor diameter just .012" smaller than the 1-16 on ruger 77s and some winchesters so I think it's a non issue all the way around. 1-14 taps/dies seem to be the cheapest of all the options. A cheap good quality 1 1/16-16 tap would be nice to find.
 
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