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Thread: 308 ak

  1. #311
    Gunco Rookie ak310's Avatar
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    Quote Originally Posted by 1biggun View Post
    I have several converted guns that shoot 308 or varients of with standard trunions. So far so good however I reload for all of them and I load tot he light side. .

    There have been reports of 308 Galil's failing. I have seen pics of a Galil bolt and I agree they look very close to a standard bolt but with a bigger face.

    IMOO and my opinion only a 5.45 bolt in a rpk,psl, m70 trunion is likely the strongestr combination the 5.45 bolt lugs are longer that has got to make them stronger IMOO .

    If I had the time, money and the parts Id love to do some improvised proof testing. Id like to see what a standard bolt and trunion can take before head space moves ir some thing lets go.
    i know its old post biggun, but curious in a 308 build and deciding which parts to use. i measured akm bulgar milled type bolt and bulgar ak74 boltto see differences. What is thicker on the 74 is the face .650 vs .720 and the 74s extractor is external ofer top of face, top rotating lug length .372 vs .412, left lug is pretty big difference .412 vs .534. OAL 3.335 vs 3.445 and fpin shaft .430 vs .345. problem i see with the 74 is the chamber face diameter starts .394, i have to bring it to around .480 based on pookies measurement for 308 win base and the bottom left cf side wall would be very thin. lol no idea if that would work out

  2. #312
    No Hope For Me 1biggun's Avatar
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    I cant tell you what bolt would have more lug stength . opening a ak 74 bolt to .470 face is going to have some issues an be harder .

    I started this thread a long time ago an I still will not tell you the conversion is safe . I will tell you I have a 308 win ak an 300 savage an a 6mm brx among others .

    I recommend you look hard a a galil 308 bolt an a akm bolt the only real differances I can see is the bolt face size , If that is true its a reasonable assumption the bolt is safe for that round if opend up if the metal an temper wre the same . who knows . its also known that saiga na veper an I think valamet have a third lug to pass CUP testing .

    the Yugo m70 an rpk trunilns an the 8mm an some 308 Yugos look to have to have the same trunions . also the the PSL has a simular trunion . so one can some what assume the trunion is up tot he task .

    I have built them I do not shoot factory 308 or 7.62x51 nato .

    I can tell you I have accidently loaded a 6mmbrx to about 100,000 psi or so an lived to tell about it the case head parilay slit the the primer blew the face of the round bent into the extracer grove on the bolt anthe case was LC nateo new case so it heavy already . I know this dont prove anything but It would be hottet than a proof load an it still head spaced ok .

    I relaod for all my 308 type aks an I try to stay on the light side. I do shoot facroy 300 savage as its a lot lighther than 308 an it gives up very littel .

    I copy the 307 win loads for 308 win an it seems to be pretty close . A 307 is a rimed 308 for weaker lever actions the dies are the same .

    with verps at about $550 you cant hardley build a conversion for taht an its got 3 lugs an a warrenty .

    I do know a light loaded 308 will blow the doors off a x39 or a 300 BO wonder round ,

    a 260rem loaded light will eat a 6.5 grendel

    an a 243 win will smoke a 6mm ar loaded light

    On of my swithch barrel guns will be a 308 win length mag well an Ill have 22-250 , 243, 308, 260 rm , 358 win an a 44 rimless of some sort . I will load them a bit light an sleep OK.

    for what its worht using winchester powders tht they claim is the same as there factory ammo there are many laods you cant even get to SAMMI max pressures even using compressed charges . I suspect Winchester factory laos are not at SAMMI MAx as they powder will not fit in to do it . I cant prove this however there old load books show max loads well under the max .

    your going from abut 7000 PSI bolt thrust to about 10,000 PSI bolt thrust .

    FWIW there is a guy on weapons guild an UZI talk who built a 300 WSM on a akm bolt . I dont think its safe but hes shooting it an is still alive . its making like 50% more bolt thurst .

  3. #313
    Gunco Rookie ak310's Avatar
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    For shooting commercial i think id go with 54r. the 308 commerical loads are often catered to bolts that might be bad even if winchester loads are well under max specs. i think most of the spec loads are going to be at least 4ksaami psi under max for liabilities. who knows how long 300wsm holds up or if it will fail in that config. magnum stuff is scary i would only shoot 300wsm with string hiding behind somtin..

    i figure standard akm bolt 762x39: 3.14 * .2235^2=.156" bthrust 8000psi@51500max, modified in 54r pressures 3.14 * .2435^2=.186" bthrust 9670psi@52000psi 10500psi@56500max and with 308win 3.14* .2354^2=.174" bthrust 10800 @62000max . medium loads i hope might get around 17% more bthrust with 54r and similar pressure 308. The heavier 203gr 54r spam loads are probably closer to max psi and greater weight bullets add more stress on bolt lugs plus it overgasses because of the load difference thats why peoples PSLs have excessive wearing after firing many heavy grainers and no regulated gas.
    the 54r case is more limited in pressures, 56.5k psi and 7.62x39 is 51.5k psi so 54r is at least around 6k less than max 308win.. My purpose would be long range target/hunting maybe elk out of standard akm parts.

    now i dunno which idea i like more, for ak700 remington rifle you describe id go with big and slow round 250gr 358 win or heavier 300-400gr 45/70 like calibers. those could be made upto mimic rus 9x39 for a subsonic thumping ak and the weight of the round would make it effective on med/big game

  4. #314
    No Hope For Me 1biggun's Avatar
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    THE 54R IS GOING TO REQURIE A LOT OF BOLT WORK OR YOUR GOING TO NEED TO GO TO A PSL TYPE PARTS THST ARE LONGER AN REQUIRE A DIFFERANT RECIVER.

    THE 54 R SURPLUS ISS NOT HE MOST ACCURATE AN THE COMMERCIA THATS MUCH GOOD IS EXPENSIVE SO YOU WILL NEED TO RELOAD .

    IF YOU NEED TO RELOAD YOU MIGHT AS WELL JUST GOT WITH A 308 TYPE ROUND THAT HAS EASY TO GET BRASS .

    IF YOU WANT A 7.62X54R JUST GET A PSL KIT AN BUILD IT AS IS . NO NEED TO REDESIGN EVERYTHING

    IF YOU WANT A 45-70 TYPE ROUND JSUT TAKE A 284 WIN BLOW THE CASE STRAIGHT AN YOU HAVE ALMOST EXACTLY A 45-70 RIMLESS WITH A NICE REBATED ,470 RIM. IT WILL FIT IN A 308 LENGTH MAG WELL ALSO .

    I HAVE BEEN WORKING ON A 44 ROUNGD OFF AN ON AS WELL THAT USES CUT DOWN 30-06 CASES .
    LOOK AT THE 444??? STUFF .

    A 444MARLIN RIMLESS IS DOABLE AS WELL AN GUYS HAVE CONVETED 4120 SAIGAS TO 4UN 444 MARLIN SEE TROMIX'S STUFF.

    lIKE i SAID A 308 GALIL BOLT AN A AKM BOLT ARE VIRTUALY IDENTICAL . THE M70 AN rpk TRUNIONS ARE PRETTY MUCH IDENTICAL TOT HE 8MM M77 .

    i HAVE NEVER FOUND A SINGLE CASE OF A AKM 308 CONVERSION FAILING . I hAVE SEVERAL 308 TYPE AKS I HAE YET TO SEE ANY LUG SET BACK SIGNS .

    I DONT CONSDIER A 300 WSM SAFE ON A AKM BOLT OR ANY TWO LUG BOLT FOR THAT MATTER .

    THIS THREAD WAS STARTED WHEN KITS WERE $75 AN 308 SAIGA WAS $500 AN AT THE TIME IT MADE SENCE TO EXPLORE CONVERSIONS AS IT WAS CHEAP WAY TO GET A 308 OR SIMULAR . NOW THAT KITS ARE $400 OR SO IMO ITS BETTER JUST TO BUY S ALREADY DOE SAIGA OR VIEPR FOR ABOUT $600 AN GAIN THE THIRD LUG AN THE KNOWING THEY HAVER PASSSED PROOF TESTING .

    greater weight bullets add more stress on bolt lugs
    BOLT THRUST IS BOLT THRUST IF THE CHAMBER PRESSURE IS THE SAME THE BULLET WEIGTH MAKES NO DIFFERANCE IN BOLT THRUST . IT WILL AFFECT RECOIL BUT THAT A DIFFERANT MATTER AB HAS NOTHING TO DO WITH THE LUGS .

    MAX psi ON 7.62X39 IS 45,000 ON ANY SPECS i CAN FIND . I have loaded them likley well above 60,000 on aks an never seen any issues or pressure signs . The brass is fine . I have seen 6mm ppc brass made from 7.62x39 loaded to likely around 70,0000 psio on bolt action target guns .

    If im going to hunt elk ill get a differat gun unless you live were elk run amuck .

  5. #315
    No Hope For Me 1biggun's Avatar
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    here is a simple to use bolt thrust calculate. not it does not use inside case diamiters in its calculations so its going to be off but its good for comparisons .

    7,62x39 ius about 7000 PSI

    a s I recall 308 win is about 10,500 or so . 7.62 nato would be a bit less as the case is thiker so the diamiter is smaller .

    https://www.google.com/search?q=bolt...sm=93&ie=UTF-8

  6. #316
    Gunco Rookie ak310's Avatar
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    i miswrote weight of bullet on lug i mean high press loads, specifically refering to guys that shot their PSL for few years with 203gr 54r biger game hunting loads probably hot spam can or hotter reloaded. I dont know if they had more issues like headspacing,lugsetback or what but for semi auto dmr meant for med loads it does cause increase wear on metal contact areas and rear trunnion/mspring rod from overgas and increased thrust.

    i would agree geometrically m77/galil 308 bolts are pretty analogous to m70/trun, but what about composition of the metal differences and in heat treatment like some people suggest. I dont know.

    762nato ~2,000 less psi and thicker case is good. 54r build from m70 would be tough just thinking about bolt/reciever is too much work. i think the best option in 308 is going 762nato thick brass and reloading withheavier lead cast is a great option for this build.

    For these builds lower threshold is good, but its not exact science. i might consider target 762nato as hot load for conversion and fairly acceptable, loads like u say to 307 / 300savage levels looks like a good level \ around 50k psi. IT is reasonable to think 100 rds a year of 308win federal whatever might be fine for a lifetime, but step it up in frequency and rapid firing or increase overall to thousands of rounds of standard loaded 308win inl yugo m70 it may fail or show significant wear to other parts.

    Supply is dry especially for the lower base production battle rifles kits, the challenge is finding bolts 308 galil/m77 and m76 even PSL bolts - i dont see them anywhere from main suppler companies only luck is by buying private/forum sellers.

  7. #317
    Gunco Regular willie's Avatar
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    Over on akfiles and on GB there is a guy selling M76 parts and seems to have a good supply. I picked up a NIB M77 after ffl fees and shipping was less than $560 total.

  8. #318
    No Hope For Me 1biggun's Avatar
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    i would agree geometrically m77/galil 308 bolts are pretty analogous to m70/trun, but what about composition of the metal differences and in heat treatment like some people suggest.
    who is suggesting the metak or the temper is different ???????????????????????

    Im sure there are differances from one country to the other . Id trust a Yugo bolt more than a Rommy but you will be very hard pressed to find much on bolt or trunion falures on any AK variant . the most mass produced weapon in the worls likely a 100 million an you will be hard pressed to find accounts of 10 failures . The ar onhte other hand will give you 50 pages of bolt failures an crap in a goggle search .

    Id trust a 308 galil an the bolt is available here an there . I doubt its any more or less special than the 223, or 7.62x39 the same factory makes . I doubt they use special metal in one bolt an less er quality in the others .

    THE FACT IS THERE IS KNOW KNOW DATA ON WHAT A ak WILL PROOF OUT AT OAN WHEN IT WILL FAIL i CAN FIND AN i HAVE BEEN LOOKING FOR 8 YEARS OR MORE .

    i KNOW OF AT LEAST 20 308 CONVERSIONS AROUND THE NET AN IN MY PERSONAL COLLECTION AN I HAVE YET TO HEAR OF ANY LUG ISSUES . THAT DOSENT MEAN THEY WONT FAIL OR THAT IT PROVES ANYTHING .

    I CAN FIND MORE PICTURES OF BROKEN MAUSERS , REMINGTON 700 AN OTHER RIFLES THAT ARE FAR STRONGER SUPPOSEDLY THAN I CAN OF AK FAILURES .

    If you hand load you dont need to worry about what the factory does . Like I said Im nit ure you can even make max pressure with winchester powder in some bullet weights.

    the nato ammo is tested a different way than the the 308 so be carefull comparing those numbers . There is info in this thread i think about that . the tweo are closer than you think from what I have gathered .

  9. #319
    No Hope For Me 1biggun's Avatar
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    6mm BENCH REST

    Here is a round that was 6 grains past a max of what should give 65,000 PSI if done right .

    It was shot on a rommy trunion with a modifed rommy bolt .

    I suspect the round was around 100,000 PSI OR MORE .

    The case is flowing into the bolt face ring an it flowed an craked into the extracter cut on the bolt , the case has a separation about hald way around an the primer blew an is falling out .

    It was a very late night mistake were I read the powder type wrong an used way to much .

    from other rounds I hae seen posted that were of known pressures Id guess this was over 100,000 PSI proof rouns do not come close to looking like this .

    I only proved the gun handled it once an there was no lug set backl . I cant prove what the pressure was but it was a lot .

    Its a wild cat im developing that is close to a 6mm brx but with a few changes . brass is lake city unfired an factory primed 7.62x51 nato . so it took a lot to do that to a military case .

    It proves to me personally that I have a margin of safety in these guns .

    I DONT RECOMED ANY ONE DO WHAT I DO OR COPY ME . I AM NOT A ENGINEER OR A GUN SMITH.

  10. #320
    No Hope For Me 1biggun's Avatar
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    6mm BENCH REST

    Here is a round that was 6 grains past a max of what should give 65,000 PSI if done right .

    It was shot on a rommy trunion with a modifed rommy bolt .

    I suspect the round was around 100,000 PSI OR MORE .

    The case is flowing into the bolt face ring an it flowed an craked into the extracter cut on the bolt , the case has a separation about hald way around an the primer blew an is falling out .

    It was a very late night mistake were I read the powder type wrong an used way to much .

    from other rounds I hae seen posted that were of known pressures Id guess this was over 100,000 PSI proof rouns do not come close to looking like this .

    I only proved the gun handled it once an there was no lug set backl . I cant prove what the pressure was but it was a lot .

    Its a wild cat im developing that is close to a 6mm brx but with a few changes . brass is lake city unfired an factory primed 7.62x51 nato . so it took a lot to do that to a military case .

    It proves to me personally that I have a margin of safety in these guns .

    I DONT RECOMED ANY ONE DO WHAT I DO OR COPY ME . I AM NOT A ENGINEER OR A GUN SMITH.

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