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Thread: .243 win based on AK innards

  1. #11
    Gunco Member kragaxe's Avatar
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    I was just looking at the engagement on both the M70 and a MAK 90. I thought more of the lugs' surface area were in contact than that. That is a pretty small amount of area in contact.

    I may go back to my original plan of making my own bolt/trunnion. Still a two lug design, but much larger lugs and surface area in contact.

    The main loads I was looking at were 90 gr bullets and lower charges, but I'd like the option of much heavier loads. That of course would require the custom beefy design.

    I'll post some schematics of the original design ideas this weekend.

  2. #12
    No Hope For Me 1biggun's Avatar
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    I think you can get a pretty decent load with the right powders. I find on the Aks that I get pierced primers before I reach max loads especialy the 223. I recomend making a load up that is the hottest that can find run a mag through by string firing and recheck head space and recheck every so often with the normal lighter loads. watch out for bullets that are over size slightly as well. that will add pressure. I see some pretty decent loads that would IMOO be safe and are pretty fast compared to max loads that are often 10,000 PSI more. the short barrel you plan on using is going to make going to hot pointless any way as there likely will still be unburned powder. most of my guns shoot the best a grain or so under max anyways.

    when kits were only $50 it was a very attractve to build a 308 or simular gun out of a AK kit but nw that there over $300 IMOO a Sagia cinversion is the better bet and it comes with a reciver and the correct bolt. I am collecting parts for a 22-250 fast twist barrel build that will be loaded lighter than the 65,000 PSI that those rounds can reach but it will still out run the 223 by a at least 250-300 fps with the heavier 70-80GR bullets I want to run. I want the case capacity needed to get the heavier bullets up to speed with lower pressure. theres a 6.5-300 savage wild cat in the works as well on a 2 lug trunion.

    If you seriously have the machinery and skills and ability to properly machine and more importantly heat treat a bolt then simply make up a three lug bolt. it will fit in a staandard trunion. the 308 sagia is only slightly wider in the lug area or it would fit a Yugo trunion. while your at it make it longer in the front and then the barrel can be moved forward slightly. I think if a company or a individuale made some quality 3 lug bolts with big stems they would sell. I certanly would be interested in a few. If your not 1005 sure of the heat treat Id not attempt it. MY 50 BMG project is on hold untill I can get it dialed in. no gun is worth your face. the $500 or so for a used Sagia (I got mine for $350) is likley the better way to go I plan on loading my 260 remington conversion up to the max. I worry about the Saiga with three lugs holding. I havent heard of any coming apart the rest of the gun is crap as far as quality fit and finish and function. if it was some thing I didnt have a way to modify Id sell it. there very rough IMOO

    good luck on the babby. hopefully in a bbout 10 years you can be fguring out how to do a 22 LR blow back for him or her.

  3. #13
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    Very nice!

    If you're going to free-float the barrel, how do you plan to anchor the foregrip? Tight fit and retaining screw into the front of the trunnion?

    Bolts have been extended before with no problem; also check Rahatakloom's 8mm conversion. You might be able to use a PSL firing pin.

    I can't quite tell from your picture; the magwell looks like it might be galvanized steel. If so, you might want to practice a bit before welding it to your receiver. Galvanized is nasty stuff to weld.

  4. #14
    Gunco Member kragaxe's Avatar
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    Foregrip will be held by 4 screws on either side. Hopefully it will be rigid enough and not wobble out the holes in the aluminum grips with use. It's 6061-t6, so it should be pretty firm.

    The magwell is 0.032" 1050 steel. It had surface rust and was sanded smooth with 400 grit wet sanding, so it has a mottled finish. The receiver will eventually be blasted and duracoated. I do knifemaking as well, so I have a hundred pounds or so of 1050, 1095 and L6 steels in sizes ranging from 0.025-0.057" that I use for making damascus/pattern-welded blades. I haven't done much in the last year due to work and moving so it's been sitting around in the Houston humidity! I'll be using some 0.057" for the trigger guard. After de-rusting, it'll probably be more like 0.045"! For welding, I'll use an aluminum block behind it as a heat sink and MIG weld it in several spots through small holes in the receiver, then grind flush on the exterior. 1050 isn't too bad to weld with mild-steel wire. The higher carbon stuff like 1095 and alloys like L6 are a pain unless you have a TIG welder.

    As for heat treating, small items like bolts are no problem, provided they are out of a metal I'm used to doing (1050, 4130/40, 5160, 1095, L6, 440C, ATS-34, S30V). I'm limited to 7" long for my electric furnaces and 14" in the gas ones. I plan on making another furnace in the next few weeks that can do 18"L x 5"dia. Right now, the pain is that I have to make a trip up to Texas A&M to get access to rockwell hardness testers. I know how to get Rc 56-62 in all my steels....the 45-50 will take a bit of experimenting. I used to do axes out of 4130 and 4140. Pre-heat to 700* and hold for 10 min, bring up to 1600*F and soak at temp for 10min. Quench into Parks 50 until room temp, temper twice at 325* for two hours each. Rc-53-54. Little hard for a bolt, though. Most seem to be Rc 44-48.

    My 10 yr old is getting a break-action single shot for early-Christmas in 357 MAX. I making an identical one, but slightly larger in .270 for my father. His will have color case hardened receiver flats. I've been doing a lot of experimenting with the coloring. Here's a couple links to videos using pretty crude, quick and dirty techniques for your entertainment...




    The 5 yr old is next in line, but he's ready to start making his own. He likes the AKs!
    Last edited by kragaxe; 09-10-2009 at 10:39 PM.

  5. #15
    No Hope For Me 1biggun's Avatar
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    good to know you not new at the heat treating and stuff.

    instead of a a break open 357 maak why not a 7.62x25?? lot cheaper to shoot. Im looking at trying to sleave a handi rifle barrel with a take off barrel rechamberd into x25 for my son to shoot. looking for a small ring mauser action for the same round. I have him shooting plinker loads of red dot (around 6 grains ) in my military 30-06 and hes getting pretty good. I may try a insert or addapter but Im concerned with the corrosive ammo that I ight get some damage in the chamber of aa expensive barrel. was also a barrel insert in a shot gun barrel might be doable and dirt cheap and then he would have two guns in one. noting wrong with the 357 max but kids shoot a lot of ammo and the more they shoot the better they get. expense of the X25 is whit im thinking.

    if H&R made a 7.62x25 handi rifle they would sell a million of them. I wish they would sell un chamberd barrels for there guns. Im looking for a 20 guage barrel to cut off and insert a rifle barrel through.

    I added a brace under my 223 varmit builds fore grip from the reciver bottom its not pretty but it works and it floats.

  6. #16
    Gunco Member kragaxe's Avatar
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    Well, I got a 9mm barrel as pert of a group buy on another forum. It's been two months now and still no barrel, despite being told it been shipped twice now, so it may get a design change!

    I'd thought about going with .44 mag since I'm set up to reload that already, it's got plenty of short-range knock down for hogs and the like, and I can find surplus barrels already chambered. There were several 7.62 cals I had considered, but inexpensive 30 cal barrels were hard to find. If I could find a heavy contour 30 cal chambered take-off barrel, I could just cut off the chamber and re-chamber. Everything seems to be "sportsman" contours that just doesn't leave much meat for rechambering. I kept finding some heavy Howa barrels on gunbroker, but they were always 1:12 twist and I wanted 1:10.

    The tokarev is a pretty cool round. I had considered that one as well as 30 carbine.

  7. #17
    No Hope For Me 1biggun's Avatar
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    that 1-12 twist might be better. the 30 benchrest guys use a slower twist than that even. 1-10 will stabelize a 210 GR bullet. I will never shot any thing that heavy. and as far as the 7.62x25 its under 100 gr. a sporting conture will have enough meat to cut off for a AK build. for a bolt action thats another matter. small ring action possably. I have a howa barrel sitting here that Im going to chamber into a .308x25 I didnt relize they were a 1-12 Ill have to check mine. thanks for the heads up. Id perfer it to be 1-12 for only a 125 GR bullet.

    the main reasion I sugested the x25 is its around 10 cents per round. you cant reload any thing for that. its not a geat hunting round but I have seen hand loads listed in the 1800 fps range.

    I just got a reamer for it and will be doing some chamberd blanks in the near future for sale or trade.

    the M1 is just to expensive to consider and to weak for most hunting. a simple
    7.62x39 rifle would be better and have more hunting uses plus ammo is while not cheap any more still pleanty avaliable.

    what rifle were you going to use for this project or were you starting from scratch?? I like the NEF and H&R handirifles plus you can get lots of differant barrels for them. Rossi makes a cheap one but not as much of a selection. remington has one now to but Im not fermilular with it.

    Kids are better off with out dealing with heavy recoil in a target shooting situation untill there big enough to handel it. I was shooting a 30-06 bolt action with no pad when I was 11 and it was tough to loose the flinch that it gave me. Dad used to make me sight it in my self. I would have been better just shooting it in a hunting situation were the recoil is not felt so much due to adrenelin. I remember shooting 5 shots at a running buck getting it and not even noticing my cut eye from the scope or the bruises on my shoulder. a chamber insert would have been a good start for me with that rifle or reduced plinker loads Like I have my 9 year old shooting at paper.

  8. #18
    Happy Camper hcpookie's Avatar
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    My .308 conversion experience is documented here on the caliber conversion forum and on my website:

    http://pookieweb.dyndns.org:61129/AKM/AK_308/ak_308.htm

    NOte that the conversion challenges I mentioned are the same things the Russians did with the .308 Saiga. So if you find any posts anywhere about the differences on a .308 Saiga vs. standard AK, you'll have everything you need.

    It is very obvious what you'll need to do if you start with the front of the mag and trunion and work back from there; you'll encounter every one of the changes that you need to make.

    Personally I am not worried about putting my face near a .308-family conversion after seeing the Yugo .308 solution is basically to open up the rim of the bolt face. Those huge locking lugs are IMO over-engineered for what they do. Now of course I'm not going to tell anyone else to put THEIR face near a .308-family conversion because you can never tell when Mr. Murphy will show up... so do be careful!

    Like biggun said if you don't get too hot with the loads you should be OK. I would think accuracy is a higher priority than sheer velocity, so you probably won't even use a really hot load anyway. I would not recommend loads that land on the right-hand side of the charts! Stay away from the red line and you *should* be OK.
    Gunco Member #10

    http://pookieweb.net


    The "original" Boltcutter Rivet Squeezers:
    http://pookieweb.net/AK/rivet/boltcutters/boltcutter.htm


    Project Pink - the Pink and Blue AK-74:
    http://pookieweb.net/pink/pink.htm

  9. #19
    Gunco Member kragaxe's Avatar
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    10 cents a round is always nice! I let my son shoot my Russian M44 this past weekend. I sporterized it with a larger buttstock and recoil pad. His expression was priceless. He said it didn't hurt, but I think his whole body moved back about a foot!

    I have two single shot scratch builds in progress. I'll be picking up a couple parts Sunday that I had someone else do on their lathe. These are complete scratch builds. Everything is being made from raw material. Most of it is 1050 steel with A2 being used for some of the FCG parts. The 270 version uses a rem700 barrel. The other is planned for 357 MAX. For plinking 38 spl could be used in it also. Of course, I may opt to go with another barrel/cal if I don't get word on the other one! I should get a little work done on them this Sunday and get some pics. I have everything to finish out the 270 now.

    I decided to make my own bolt and carrier for the 243. I'll use the M70 and/or MAK-90 as a template for most of the cuts. The front of the bolt is going to extend out some. This will put the hammer/iring pin back into the correct positions as well as allow me to do a third lug easily. The front trunnion is being made custom as well. Pretty much identical as the stock one, but with a slight mod to the lower left section (left when facing chamber). I might dicker witht the rotation since the rotation extension won't be part of the lug anymore. I can probably get another 10* of rotation for more lock-up surface area.

    Looking over most of the load data for the 243, I envision being in the 46-48K CUP zone. Maybe up into 50-51K. I have no experience reloading 243, but 300 WM and 44 Mag seem to work best at about 85% and 75% max loads. There were some loads developed by encore shooters with 15-18" barrels that I've been mostly looking at since I plan on using 18" barrel.

  10. #20
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    You're going to make the front trunnion, bolt, and bolt carrier?

    I spent some time earlier this year sussing out the machining steps for those parts, and decided my round tuit list is long enough that my current project would never get completed if I got sidetracked that far.

    The bolt is fairly straightforward. Some Valmets, Galils, and Norincos came with a different firing pin and an internal spring to keep the firing pin from dinging the primer when the bolt comes into battery; not a problem with Commie military ammo, but it'd be a nice extra bit of safety for softer civilian primers. The couple of bolts I have on hand look like the spaces between the lugs were just gnawed out with small end mills, not particularly sharp. It doesn't matter since the only part of the bolt head that counts is the lugs; the rest is just cut back for clearance. Startling after looking at Mauser or Remington bolts, though. There's a thread over in the Saiga subforum with some good pictures of the Saiga 3-lug bolt. They just added some meat to the ramp that normally slides over the top of the cartridge when the bolt moves back. Damned if I can see why it doesn't ding up the shoulder, but it appears to work.

    You can do most of the internal cuts in the front trunnion with standard keyseat cutters, though you might have to grind the shanks a bit to clear the trunnion. The trunnion has a lot of cuts that don't serve any mechanical purpose for the firearm. I originally thought they were lightening cuts, but my new theory is that they're intended to reduce thick sections that might cause problems with the heat treat. Also, looking at the Yugo trunnion by my keyboard, it looks like the front was faced off on a lathe. Presumably the barrel hole was bored at this time, and all other dimensions and machining ops came from the front and the hole centerline.

    If you're using a manual mill, some of the cuts in the trunnion will be "blind", with only the crank dials or DRO telling you where you are.

    The bolt carrier is more complex than it looks. It will need lathe ops to do the spring hole and snout, then you'll have to make a jig to hold it to a virtual center along the centerline of the bolt and cut the internal cam groove. You could do it by hand with plenty of patience, but normally you'd need a 4th axis on a mill table.

    Both (or all three) of the locking lugs are in different planes. I'm not sure why this was done, and it surely complicates duplicating the original. Someone may know and interject the reason; otherwise, I'd think about just putting them all in the same plane, and then you could cut all three locking faces in the trunnion on the same setup.

    For your .243, I'd recommend using the thicker Yugo-style receiver and duplicating the Yugo trunnion, which is narrower, has a different rivet pattern, and appears to be stronger around the locking lug area.

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