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Thread: 8MM Mauser Bore and CUP limits ???

  1. #1
    Boolit Master
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    8MM Mauser Bore and CUP limits ???

    Gents... Have a SAMCO EXCELLENT M24/47 Yugo 8 MM Mauser. (will post pics if I can get them on here..it is EXCELLENT). So..need to reload and shoot,,yea... Got my Speer #14 out and started reading..OK good so far.. But,,they warn, and rightfully so..NO OLD MAUSERS for this reloading data. TWO REASONS....

    #1. Bore on old 8MM's is .318" and "new'ones is .323". Good, understand the problem here well engough..so.. do I 'slug' my barrel to find out,or is there a way to determine the bore with out all that guff? I think there should be an easy cut off point some where.

    #2. The KICKER. is CUP...they warn 'old' ones have a CUP Limite of 37K and new ones are OK to the European limit of 50K. If we look at this..the 37K is 30-30 CUP limits and the 50K is up to the .308 Limits...much...much better.. Now this mess gets spicy... THEIR RIFLE during testing was an old M98 VZ 24 Czech rifle with 24" barrel...UGH!

    So,, question here is..is the YUGO 24 good for 50 CUP? We know an old VZ24 is..my guess is yes..but...need input...feed back ..opinions...knowledge...

    AND LASTLY...what is a good Cast Boolit for this baby? the Copper plated fodder is very bland...

    Thanks guys...

    NOSE DIVE

  2. #2
    Boolit Master Beekeeper's Avatar
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    Yugo 24/47

    The 24/47 were all the 323 boolit.
    It is best to slug the bore to find the best boolit for each weapon.
    I have 2 of them that I bought from J&G Sales and they are both good shooters.
    One has a little bit of a dark bore and the other like new.
    I don't know about the 50 CUP but both of mine are great cast shooters but again you need to slug the bores to make sure about boolit size.

    I hope that helps some,


    Jim

  3. #3
    Boolit Master spqrzilla's Avatar
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    The lower CUP limit is for Commission rifles, even small ring Mausers can handle more than 37K. Ignore all that discussion, it has no applicability to your rifle.

  4. #4
    Boolit Master
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    No worries re: pressure - it'll handle anything recommended for 8 mm. Slug the bore to know for sure, but you're probably going to want to shoot something in 0.325". Bullet recommendations will depend on application. For general use probably something gas-checked will be the best in terms of satisfaction:effort. The Lee mold is cheap and usually good. But then you have to figure-out how to size them (but this is all part of the fun): http://www.midwayusa.com/viewProduct...ductTabReviews

  5. #5
    Boolit Master
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    Thanks guys... Just reviewed my posting on YUGO MAUSER site and was reassured mine in 99% 323.. OK..good so far. Only issue is the 37K vs 50K CUP. Posting on MAUSER site says we are OK if we have a rifle in the WW2 and later catagory. SPEER is protecting themselves which makes sense. I also have a CARL GUSTOFF 6.5 x55 Mauser and have not 'loaded her up' but have been told, CARL"s stuff is good to go. Well..now...what we need here is a good 150 gr. 8 MM mold..and I like Gas Checks... have plenty linotype mix..so good there...NO gas checks in 323 varitey... OK..I'll tell on myself...I don't have my 8MM dies yet either!

    Am now ordering an 8 MM Czech, CZ24 from AIM.. My SAMCO copy is a YUGO. Any comments form anyone which is a "better" rifle... "all things being the same".. that is..

    Age..rounds though the rifle..Oh..what else....ABUSE is the Same. Ok, Let's do this..if we can... both the YUGO and CZECK..made the same day..used by the same guy..same treatment..(cleaning..rounds shot..storeage..) All things being equal... (Oh boy, I can't wait for this on this site!)..

    Which is the better rifle?...or BOTH the same?

    Thanks guys. Really need feed back on if this ole YUGO can handle the 50K CUP?

    Thanks again...

    Nose Dive

  6. #6
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    SAAMI lists a MAP (Maximum Average Pressure) of 37,000 psi (piezoelctric transducer) and CIP (European version of SAAMI) lists a MAP of 56,600 - 57,000 psi.

    I've done a considerable amount of pressure testing in my own Yugo VZ24/47. Some old Rem-UMC Factory ran 37,300 psi(M43) and some old Winchester Super Speed ran 40,000 psi(M43). Most of the Turk Milsurp, some German '39 and other milsurp with 154 gr bullets ran 53,700 to 61,300 psi(M43) if the velocity was 2850 fps or so (standard velocity for this ammo out of this barrel length). All of the German, Equadorian and some unkowns that have the 196 gr bullet push 52,300 to 55,000 psi(M43) if the velocity was over 2400 fps.

    Many have assumed the Turk ammo was "hot" because of sticking cases. While it is loaded right up there it is not "hot" for a M98 action. Truth is the Turk cases were not annealed at the shoulder and neck and do not spring back after obturation. I have pulled the bullets and powder from several lots of Turk ammo and loaded it in WW cases. Velocities and pressures were essentially the same and extraction was normal. The stickiness was due simply to the brittle Turk cases. I also have pulled thousands of the bullets, resized the necks (about 8% split and are discarded), recharged with 5% less of the powder and then reseated the bullets and crimp with a LFC die. For me that's not difficult using a Dillon 550B. Velocity drops to 2715 - 2740 fps and the psi is down to 49-50,000 psi(M43). It is a comfortable load and extraction is normal.

    So to answer the nose dive's question; yes. Phot shows my VZ24/47 and the wire attached for the pressure measurement via an Oehler M43 PBL.

    Larry Gibson
    Last edited by Larry Gibson; 10-17-2010 at 05:46 PM.

  7. #7
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    Quote Originally Posted by Nose Dive View Post
    Am now ordering an 8 MM Czech, CZ24 from AIM.. My SAMCO copy is a YUGO. Any comments form anyone which is a "better" rifle... "all things being the same".. that is..
    Nose Dive
    ..........So far as basic design and strength they were both hatched out on the same stump.

    ..............Buckshot
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    Boolit Master GrizzLeeBear's Avatar
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    #1 They stopped making .318 bore Mausers a L-O-N-G time before the CZ24 and 24/47's were made. But, go ahead and slug them so you know what size the bores are for shooting cast boolits. My 24/47 has a "mint" bore that slugs .322 - .323. The nice thing about the 24/47 is that they were Serbian model 24's that were refurbished/rearsenalled in 1947 (hence the name 24/47). In many cases this involved having a new barrel put on before being reblued and then put into cosmoline and stored. It might be a good idea to COMPLETELY disassemble the rifle (including the bolt) as they can be totally filled with cosmoline. Kind of a pain, but you only have to do it once, and all the cosmoline is why they are in such good condition.

    #2 the lower pressure limit in the reloading manuals is for the older 1888, 1895 rifles. Any 98 mauser (including the CZ24, VZ24 and 24/47) in good condition will easily handle 50K loads. The usuall caveats apply - start near the bottom of data and work up. This is of course with jacketed bullets. You will not be able to get anywhere near that hot with cast boolits. I find that gas checked cast boolits work best at 25K - 30K and 1600 - 1800 fps. And you can shoot a LOT of them and not beat yourself up like full power jacketed loads do.

  9. #9
    Boolit Master
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    i'm going to agree with grizzleebear,you ain't going to be able to push cast boolits that fast succesfully. they will lead the bore like crazy. you will have start low and work up, even the low side of j- words is to fast for cast, stay between 1500-1800fps. imr 4895 is a good place to start. but there is alot of powders you can use. and if you use j-bullets and work up 50k, i think you'll give up before you get there, unless you just love pain!!!

  10. #10
    Boolit Master
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    Thanks guys. Ordered my dies and some powder this morning. Still shopping for a mold and batch of copper clads to work on the loads.

    Sent AIM my money for the Czech rifle. So, we will see what we will see..

    Thanks for all the input and feedback. I am much more comfortable about kicking up the pressure past the 37K limit...

    Thanks again guys.

    Nose Dive

  11. #11
    Boolit Master

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    You'll need to slug that bore and size your bullets larger than groove diameter. I prefer to use as large diameter as can be chambered without dragging on the case necks. Loading cast is different than loading jacketed, and powder choices may be considerably different.

    Pressure limits don't concern me much when shooting cast as accuracy generally goes south before pressures and velocities get high, and this most likely will be the case with a military barrel and chamber.

    Do yourself a favor and make it shoot accurately first, and then work on higher velocity loads.

  12. #12
    Boolit Master
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    The VZ 24 and the Yugo 24/47 are essentially the same rifle. The Czecks originally made the first batch for the Yugoslavians until the Yugoslavians bought the rights to make them for themselves. After the war The Yugoslavians rebuilt the rifles that they had and changes a few things like where the sling swivels are located and stamped the receivers 24/47 after the year that they adopted the changes. Basically they are the same gun. I have a VZ 24 and a 24/47 and except for markings and a few cosmetic differences you can't tell them appart.

  13. #13
    Boolit Master
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    My 24/47s are mid-length actions. If memory serves (and it doesn't always) the Vz 24 is a standard length action. This won't make any difference unless you sporterize: You might have a hard time stuffing something based on the -06 case in the shorter action, and magnums are out completely. But for the standard Mauser cartridges, the 24/47 might actually be more ergonomic.

  14. #14
    Boolit Master
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    A good boolit for the 8mm can be found here:

    http://castboolits.gunloads.com/showthread.php?t=88897

    Order it in a multiple cavity mold and have the extra cavity hollow pointed and you get 3 molds for the price of one (pointed, flat nose, and HP). If your bore sluggs slightly oversize (mine came in at .3235") the .326" size will give you plenty of room to size to your need.

  15. #15
    Boolit Man
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    FWIW my M24/47 shoots .323 sized and GC Lyman #323481 (obsolete 185 gr.) better than my jacketed at 100 yds. rested. Got lucky and stumbled onto this, my beater Yugo outshoots my Krag sporter w/peep and my K-31 (with cast loadings) Not that the gun is a better grouper , just lucked into a good load / gun combo. I loaded up some rounds and shot at clay pidgeons at a 90 yd. sand pit and hit most of them with in 3 shots apiece. Surprised me because the sights are comparatively crude. Best paper target was a 12 shot group at 100 yds using a 5 1/2" bull ...Group was 1 7/8 ' wide and 3 3/4' long ...but 8 of those shots were X and 10 and 6 of those could be cvered with a with a .50 cent piece...got to learn how to scan stuff ...Load was with 20.5 gr. AA5744 and afore mentioned bullet and what ever cases I can scrounge up...HTH...Tedly

  16. #16
    Boolit Master

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    Quote Originally Posted by Nose Dive View Post
    Posting on MAUSER site says we are OK if we have a rifle in the WW2 and later catagory.
    Patently incorrect. Witness the Brazilian Model 1908 and Argentine Model 1909. They are two of the finest made, most often customized 98 Mausers ever made. Their strength is by no means sub par with later 98 Mausers. This comment, "WW2 and later...." is a unwise observation. Late WW2 K98k meaning 1944 & 1945 are seen as being of dubious quality due to wartime production. This is especially so with 1945 produced K98k.


    Czech, CZ24 from AIM.. My SAMCO copy is a YUGO.
    Czech rifles are generally seen as being metallurgically superior.

    The Czech Vz24 is a standard long action. The Yugo Model 24 is an intermediate length action. The bolt face is different on the Yugo.

    You really need a good Mauser book if you intend on owning many Mausers. Ludwig Olsen's Mauser Bolt Rifles is available from Brownell's. Robt. Ball's Mauser Military Bolt Action Rifles of the World 4th edition is an excellent reference.

    Dutch

  17. #17
    Boolit Master

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    Quote Originally Posted by NickSS View Post
    The VZ 24 and the Yugo 24/47 are essentially the same rifle. The Czecks originally made the first batch for the Yugoslavians until the Yugoslavians bought the rights to make them for themselves. After the war The Yugoslavians rebuilt the rifles that they had and changes a few things like where the sling swivels are located and stamped the receivers 24/47 after the year that they adopted the changes. Basically they are the same gun. I have a VZ 24 and a 24/47 and except for markings and a few cosmetic differences you can't tell them appart.
    Un-correct.

    The Yugo/Serbian Model 1924 was made by FN in Belgium originally. Not Czechoslovakia.

    They are not the same rifle, not even the exact same physical features.

    This is where book learning would come into play...

    Dutch

  18. #18
    Boolit Master
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    Thanks Dutch... Why do you say the CZECH has better METAL...DATA?? Does it Look better,,,aka, better machine work. or is the 'metal stronger' composition?

    I was told this twice now,,and no one has provided 'data' to support this other than opinion,,,which I do respect and appreciate. Does the 'BOOK" show this? If so,,will order it now... If it provides data,,,traceable to specific aresenals...rifles...places..times..compostion data...

    Thanks buddy...

    Nose Dive

  19. #19
    Boolit Master
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    Nose Dive

    I like accuracy with my cast bullets. It isn't very likely you'll be finding any accuracy with a 50 K pressure load behind a cast bullet in an 8 X 57 mm.

    If you're wanting to shoot cast and you're concerned about the gun being able to handle 50 K, I just don't understand ? ? ?

    Most cast loads that will shoot well out of your 8 mm will be in the 20 K - 25 K range.

  20. #20
    Boolit Master

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    Quote Originally Posted by Nose Dive View Post
    Thanks Dutch... Why do you say the CZECH has better METAL...DATA?? Does it Look better,,,aka, better machine work. or is the 'metal stronger' composition?

    I was told this twice now,,and no one has provided 'data' to support this other than opinion,,,which I do respect and appreciate. Does the 'BOOK" show this? If so,,will order it now... If it provides data,,,traceable to specific aresenals...rifles...places..times..compostion data...

    Thanks buddy...

    Nose Dive
    Some of what you demand as proof won't be found as proof in the manner that you'd understand easily, i.e. 2+2=4.

    First, understand the Czech arms industry was just that. It was a deeply cultivated and practiced industry.

    When I say "superior" I mean metallurgy. The Czechs had/have a steel industry that nobody looked down their nose at. It was a well respected industry. You might have to read a dozen books to get the information you want. You could start with Ludwig Olsen's book but I don't think that would satisfy you. You could move on to Jerry Kuhnhausen's book "The Mauser Bolt Actions, a shop manual". But this is really one of those subjects where you'll have to do your own homework. If you're an NRA member you could write to NRA and ask for information as I know there's been much written on the subject by them in American Rifleman over the decades.

    I'm a google keyword search junkie. Depending on how you phrase search words or terms there's very little you can't find.

    http://econc10.bu.edu/economic_syste...ep/czarms.html

    Written by a Dutch dude. Has to be good!
    http://www.aug.edu/~sbajmb/paper-dutch.PDF

    Czech steel industry
    http://www.hz.cz/en/history-of-steelmaking


    Dutch

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check