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Thread: rommy 7.62x54???????

  1. #11
    Gunco Veteran muttman's Avatar
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    Quote Originally Posted by hcpookie
    As in a Saiga .30-06?
    yes their is one.

    muttman



    http://forum.saiga-12.com/index.php?showtopic=13147

  2. #12
    Gunco Regular acmech's Avatar
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    Quote Originally Posted by hcpookie


    NOW. A .308 bolt may - MAY - be able to handle the higher pressures. It has been discussed that the Saiga .308 3-lug bolt MAY be able to do so, but no one has pursued this. You'd have to enlarge the bolt face for the huge -54r rim. And you'd be in uncharted waters.

    Who was it that had calculated the pressures? That is in the .308 conversion thread I think. May be some promise there.
    From what I've been reading on the saiga forum, the bolt an trunnion in the saiga 30-06 is identical to .308. According to the Hodgdon site, the 7.62x54r makes between 36,000 and 49,000 cup. the .308 makes on average 50,500 cup. My primary interest is the 8mm which generates between 36,000 and 49,000 cup. So you see, the saiga .308 guns are well strong enough for a 8mm or 7.62x54r conversion. The 30-06 by the way make 48,000 to 50,000. No question about it, according to the pressures generated, the .308 requires the strongest action between the 8mm and 7.62x54r. The 7.62x39 parts people want to use worry me, they may be strong enough, but were built for a round that generates 40,000 cup max, it your choice though and I really hope it works for ya.

    I just love info., and like looking at this stuff, check out this stuff here http://www.hodgdon.com/data/rifle/308win.php
    http://www.hodgdon.com/data/rifle/7.62x54r.php
    http://www.hodgdon.com/data/rifle/857mmmau.php
    http://www.hodgdon.com/data/rifle/76239mmr.php
    I also love the free reloading info.

    I am going to do a 8mm conversion of the .308 saiga. I just won a 24/47 barrel on ebay with a bright shiney bore for $49 shipped, and I got a mg 13 mag to look at and it is only 1/16 narrower than a standard ak47 mag. so it will work fine. All I need now is a .308 saiga for $350-$400, and I'll be happy. The only hard part will be possibly moving the ejector rearward if needed, making the mg 13 mag. fit won't be too bad. You may ask "Why a 8mm when 30-06 is available" well, 2 reasons, first is because I can, second, I have 10k of romanian surplus 8mm

  3. #13
    No Hope For Me 1biggun's Avatar
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    the .308 makes on average 50,500 cup
    the SAMMI pressue limit for the 7.62x51 is around 51,000PSI BUT the 308 WIN Sammi limit is around 61,000PSI. there is a differance between how these rounds are rated. the nato stuff is around 50,000 but 308 loads are 58,000 PSI with many puplished loads at 60,000 PSI

    The 30-06 by the way make 48,000 to 50,000.




    The 7.62x39 parts people want to use worry me, they may be strong enough, but were built for a round that generates 40,000 cup max
    ,

    If recall correctly the 7.62 x 39 Sammi max load is 45,000 CUP this comes out to around 50,000 PSI( very close to the 7.62x51 nato ) when converted. most of the loads for this round in my Lyman book are in the 44,000 CUP range. I have seen loads as high as 50,000 psi but not an indication as to what type of gun they were fired in. possably a bolt action.

  4. #14
    No Hope For Me 1biggun's Avatar
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    the .308 makes on average 50,500 cup
    the SAMMI pressue limit for the 7.62x51 is around 51,000PSI BUT the 308 WIN Sammi limit is around 61,000PSI. there is a differance between how these rounds are rated. the nato stuff is around 50,000 but 308 loads are 58,000 PSI with many puplished loads at 60,000 PSI

    The 30-06 by the way make 48,000 to 50,000.
    this must be cup pressures as most of my books have -06 up to 60,000 PSI. I dont remember what the SAMMI spec is.
    I am pulling these specs out of my head so dont use them as FACT. most of this info is on my 308 conversion thread as well.






    The 7.62x39 parts people want to use worry me, they may be strong enough, but were built for a round that generates 40,000 cup max
    ,

    If recall correctly the 7.62 x 39 Sammi max load is 45,000 CUP this comes out to around 50,000 PSI( very close to the 7.62x51 nato ) when converted. most of the loads for this round in my Lyman book are in the 44,000 CUP range or about 50.000PSI. I have seen loads as high as 50,000 cup puplished but not an indication as to what type of gun they were fired in. possably a bolt action.

    keep in mind that rim DIA is a factor when figuring bolt thrust to a 7.62x54r is going to produce more thrust against the lugs than a 7.62x39 with the same chamber pressure, there are guys using Rommy kits for 308 conversions but it should be kept in mind that the 2 lug guns would not pass the european proof tests thus the sagias having three lugs.
    it should also be noted that the european use higher pressures than the USA. the yugo 8mm and 308 military guns use a 2 lug bolt and the trunion is almost identical to the m70 in 7.62x39. the 223 is loaded at over 51,000 cup or aprox 58,000 psi but the bolt thrust is less due to the small rim dia.

    I personaly use yugo trunions on all my conversions (except 223) it may not be nessacry but the few extra $$ for the trunion makes feel a little safer.
    You are correct that the 8mm is not as hot as the 308 or the 7.62x51 round HOWEVER KEEP IN MIND THAT IF YOU DECIDE TO USE EUROPEAN FACTORY (LIKE NORMA) SPORTING LOADS THEY ARE EVERY BIT AS HOT AS A 308 AND 30-06 LIKELY IN THE 60,000 PSI RANGE. The US loads are down loaded so they are safe in the pre 98 guns and the ones that the bores is not a tru 8mm. inother words stick to surplus militatry stuff and even some of that is pretty hot if it is for modern machine guns.

  5. #15
    Gunco Regular acmech's Avatar
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    The max Hodgdon load for the 7.62x39 I saw was, 40,000 cup, but even if pressures are the same as surplus 7.62x51, the surplus is very hard to find now, and your stuck reloading to be sure your bolt doesn't give under 60,000psi commercial .308 right? It still seems like your going to have a gun that will work fine with surplus, but you should sweat about running .308 commercial, that is what worries me. The saiga's were made to shoot it all and the bolt is bigger and has 3 lugs.

  6. #16
    No Hope For Me 1biggun's Avatar
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    no argument that a sagia would be a better start.
    the lyman book shows a load for 7.62 x39 of 34.5 grains of h-335 producing 43,000 cup.
    I do recall the hodgen site loads were a little tamer than other sites. As stated before the SAMMI has the 7.62x39 at 45,000 cup if rated in PSI it would be higher likely around 49,000- 51,000. there is susposedly no exact formula for doing the conversion. I agree that 308 win loads at 60,100 psi may be pushing it. What is interesting is there are 308 loads shown in the Lyman book listed as max loads that only make 44200 CUP. but have a FPS of 2992. this is a huge improvement over the max 7.62x39 load by700- 800fps with the same or less pressure. An example is this load here. 50.6 gr of win 748 with a 130 grain SP bullet does 2992 FPS with a cup pressue of 44,200. that same powder at the starting load of 44 grains still pushes the same bullet at 26,400 FPS( aprox 200-300 FPS faster than a good AK load) and only produces 30,200 CUP this is 15,000 cup under the SAMMI spec for the 7.62x39 round. I personaly feel that these loads IMOA would be safe in a Rommy conversion. Of course you will have to reload and this is not the way to go for shooting dirt clods. but if you want do sojme hunting or long range work this would be the ticket. I am working on a 14" pistol in 308 win on a yugo trunion and hope to have it done by this deer season. I plan on using hand loads in the 50,000 PSI range. You can bet that I will string fire it a bunch before using it.
    I would like to get a good look a a sagia 30-06 and see how they make it fit. there are pics posted some were that show it but holding one in my hands wold make it simpler. an 8mm on a sagia that can shoot max loads would be great cheap ammo for plinking and $35 abox stuff for hunting. the ammo savings would pay for the sagia donner gun pretty fast.

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