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Thread: 8mm on a romy kit?

  1. #11
    Gunco Member bert01's Avatar
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    i do have a 44mag barrel laying here staring at me, exspensive to feed though

  2. #12
    No Hope For Me 1biggun's Avatar
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    8mm comercial rounds in the US are way under what the 308 is loaded at. europeans however factory load the 8mm to full potential. there are to many pr 98 mauser bolt actions that will not handel the pressures so the US loads weak. the hotest load in my lyman book is 48,000 PSI not CUP simiular loads rated with the cup meathod are around 35,000-40,000 CUP, About the same or less as 7.62x39 the hotest hand load shown for 7.62x39 is 44,700 cup if it were rated in PSI it would likely be around 50,000 psi based on other loads listed but dont take my word for this. 8mm bolt thrust would be higher as the case head is slightly larger and the same as the 308. bolt thrust is what I feel should be considerd most important. for example there are max loads listed in the book for the 223 at 51,800 CUP, not PSI but the smaller.378 case head means there is less bolt thrust than a 308 WIN with the same PSI in the chamber as it has a .473 case head. some were on this site I think it was posted on my 308 AK post there is a formula for figuring out bolt thrust. It involves square route and math I dont know how to do. It would be great if some one could figure it out and post some numbers here. 8mm mauser barrels can be found on ebay for around 10- dollars I bought 4 one time for $15 for all.

  3. #13
    Gunco Member bert01's Avatar
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    i agree, bolt thrust should be one of the main concerns and i have seen this mention in your post

    check this out http://www.riflebarrels.com/articles...g_strength.htm

    ill be working on this tonight

  4. #14
    Gunco Member bert01's Avatar
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    anybody know the steel type and rockwell num for ak bolts

  5. #15
    No Hope For Me 1biggun's Avatar
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    Bert o1 great link. the steel is likely very simular to 4130 no clue as the hardness. I think just knowing the bolt thrust of each round would be a good place to start. by knowing 7.62x39 one could compare others to see were they rate. we know the action is good for 7.62x39 and 223. what I want to know is how much higher the 308, 8mm are as well as the 223. I would also like to be able to figure out the 6mm ppc 6,5 grendal 6.8 rem 458 socom 50 beowulf the last 2 have a rebated rim I am guessing you would use the largest ID of the casing?? MY math skills are poor or i would have been an engineer or somthing else in life. tony at Tromix lead delivery built a 458 SOCOM on a milled ak reciver with a standard AK bolt.

  6. #16
    GuncoHolic Sprat's Avatar
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    If you checked last week I asked for the chamber pressures for 7.92 kurtz vs 7.62 x39mm
    unless you have a romak 3 kit or a trunnion for a 308, the pressure will be too great for 8mm. you will need a 308 bolt or open the 7.62x39mm bolt face, you will need to convert a existing 8mm mag to the ak design, and a 8mm barrel. After a lot of thought and in possession of a Romak 3 kit, I am going to keep it in 7.62x54R.
    I decided to go 7.92 x 33 kurtz, as the chamber pressure is simular to 7.62 x 39mm. I have a lot of 7.92 kurtz (EG) plus Partizan has started producing it again (reloadable). I got the 8mm barrel and a polish trunnion, I saw one of the companys selling the front sight and gas block's, mags will work.

    some good post above, shame two pages and few good answers

    sprat

  7. #17
    No Hope For Me 1biggun's Avatar
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    unless you have a romak 3 kit or a trunnion for a 308, the pressure will be too great for 8mm
    .

    Sprat there are a lot of guys bulding 308's on AK 47 trunions. the 8mm has less chamber pressure than the 308 so I dont feel that this is an issue .If the 308 is safe that is. the m77 trunion and boltface appear almost identical to the m70 trunion and bolt face, only the stem of the bolt is longer and face is enlarged there were pics on my 308 post but that member removed them when he left this site the are on another site now. opening up the bolt face is not a big issue the mag can be used from a m76 if it can be found as it is a 8mm AK, or some type of 30-06 mag as it is slightly longer,. most of the build problems are adrdessd here.
    the one question that myself and every one would like to know is what can a AK bolt and trunion handel as far as bolt thrust. the saiga 308 has three lugs and I have seen posted that that is due to the very high pressures that the europeans test at (higher than the SAMMI). some were this info must be puplic. there are however numerous military AK variants that have only 2 lugs

  8. #18
    Happy Camper hcpookie's Avatar
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    Quote Originally Posted by bert01
    i've read through the other post but didnt seem to see a conclusion as to what to build off of and what not to, maybe im just being blind and dense, i never can tell

    im planning on doing a 308 on a m70 or bigger later and had the romy kit sitting here
    We came to the consensus that either a ROMAK-3 kit or Saiga .308 donor rifle would be the best place to start... since these are built for 7.62x54r or .308, respectively, they are already "reinforced" from the factory for the more powerful rounds.

    That will be closest to the already-in-use Yugo 8mm Sniper model. OR just buy a Yugo 8mm kit and alter it.

    I know that I would not want to be the first one to try it!

    HTH,
    - Jerry

  9. #19
    Gunco Member bert01's Avatar
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    would someone be kind enough to post some pics or point me in the right direction to pics of the 308 bolt and trunnions mentioned above

  10. #20
    Gunco Member bert01's Avatar
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    im looking at machining some front trunions and bolts to match, that way you can get the lock up and the length right, but ive got sooooooooo many project i dont know how long its going to take me to get around to it

    dont worry as soon as i start ill post everything

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