Gunsmithing My 300-338 Lapua Magnum Project

LRI

LRI

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Minuteman
    • Mar 14, 2010
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    Sturgis, S. Dakota
    www.longriflesinc.com
    #1
    My little ongoing saga is about to take another turn.

    A 32" 30 caliber 1:17 twist barrel arrived a few days ago from Benchmark. My hopes is to reach 4500fps using a 125 ballistic tip. (speed kills)

    Haven't had the chance to turn "Don The Phenomenon" loose on the lathe yet to get it hung, but I'm anxious to see what happens.

    The current barrel is a 10 twist Bartlein and I hit a wall at 3200 with 210 La-poo poo OTM's. Bummer. I was hoping for 3400. I've used the full gamut of powders and thus far Retumbo has yielded the best result. (RL25, RL33, N570, 50BMG, and H1k were also tried).

    I've never monkey'ed with duplex/triplex loads as it just seems to be a trip to the ER if you goof up. Might have to step up and get funky. It's just an eyeball or two right?? :)

    So, time will tell how this goes. Years ago I did one and got 4375fps with 125's out of a Lilja barrel. That speed was according to COR-BON ammunition's chrony in their test tunnel.

    Fun stuff. Really curious to see what this does in a plate match or a coyote this winter.

    C.
     
    #5
    Have not considered a GT barrel. From the limited experience I've had with them, they've not run as well as a well done cut/button barrel in the std twist configuration.

    Maybe they've improved, but years ago, we ran into accuracy issues.

    Don decided to hang out late and he's chambering her up as I type this. Should be fun!

    C.
     
    #7
    Wow! I can currently only imagine such a pursuit, but am interested in reading about it and the end results nonetheless. Were I closer to you, I'd love to see it and the results in person, but that isn't to be.

    So, for the unwashed and uninitiated, is that 32" .30 cal. 1:17 twist barrel a custom order? It seems a given, but then I'm not in the know.

    Also, other than the pursuit of an amazingly fast .30 caliber projectile and the devastation it could cause, what is the purpose of this project? Or is it a case of "If you have to ask, you wouldn't understand."?

    Ultimately, it doesn't matter what folks like me think. This still seems like a fun project for "just because".

    Keep us posted.
     
    #10
    lash said:
    Wow! I can currently only imagine such a pursuit, but am interested in reading about it and the end results nonetheless. Were I closer to you, I'd love to see it and the results in person, but that isn't to be.

    So, for the unwashed and uninitiated, is that 32" .30 cal. 1:17 twist barrel a custom order? It seems a given, but then I'm not in the know.

    Also, other than the pursuit of an amazingly fast .30 caliber projectile and the devastation it could cause, what is the purpose of this project? Or is it a case of "If you have to ask, you wouldn't understand."?

    Ultimately, it doesn't matter what folks like me think. This still seems like a fun project for "just because".

    Keep us posted.
    Click to expand...




    Here's why:

    Strelock ballistics program

    220 Lapua OTM Scenar @3200fpsmv (.605BC) vs. the 125 Nosler ballistic tip @4500fpsmv (.435BC)

    Velocity: Come Up: (MOA) Time of flight: (Sec.)
    200 yard zero: 220:2848 125:3923 0/0 .21/.15
    1k distance: 220:1898 125:2353 19.89 /10.7 1.24/.94
    1M distance: 220:1215 125:1308 54.27/33.76 2.72/2.23


    Near as I can tell pushing a feather at ludicrous speed gives an edge on all fronts. Granted, barrels become even more expendable, but I happen to know a guy that can hang one fer nutin. :) Bench racing a cartridge is fun, it'll be interesting to see how it really plays out. With both barrels now fitted up conducting a side by side pepsi challenge will be a snap.

    So, we'll see. Hope to have it sorted out in time to maybe enter a few of the local LR matches around here over the summer.

    C.
     
    #11
    lash said:
    Wow! I can currently only imagine such a pursuit, but am interested in reading about it and the end results nonetheless. Were I closer to you, I'd love to see it and the results in person, but that isn't to be.

    So, for the unwashed and uninitiated, is that 32" .30 cal. 1:17 twist barrel a custom order? It seems a given, but then I'm not in the know.

    Also, other than the pursuit of an amazingly fast .30 caliber projectile and the devastation it could cause, what is the purpose of this project? Or is it a case of "If you have to ask, you wouldn't understand."?

    Ultimately, it doesn't matter what folks like me think. This still seems like a fun project for "just because".

    Keep us posted.
    Click to expand...




    Here's why:

    Strelock ballistics program

    220 Lapua OTM Scenar @3200fpsmv (.605BC) vs. the 125 Nosler ballistic tip @4500fpsmv (.435BC)

    Velocity: Come Up: (MOA) Time of flight: (Sec.)
    200 yard zero: 220:2848 125:3923 0/0 .21/.15
    1k distance: 220:1898 125:2353 19.89 /10.7 1.24/.94
    1M distance: 220:1215 125:1308 54.27/33.76 2.72/2.23


    Near as I can tell pushing a feather at ludicrous speed gives an edge on all fronts. Granted, barrels become even more expendable, but I happen to know a guy that can hang one fer nutin. :) Bench racing a cartridge is fun, it'll be interesting to see how it really plays out. With both barrels now fitted up conducting a side by side pepsi challenge will be a snap.

    IF the numbers are even reasonably close I think it may prove worth it. The reduction in come ups, time of flight, and the smaller cross section of the lighter bullet all adds up to less off call shots due to wind.

    So, we'll see. Hope to have it sorted out in time to maybe enter a few of the local LR matches around here over the summer. The energy delivery inside 400 yards is almost identical to the 220 so if a 220@3200 doesn't tear up steel then a 125 going 40% faster hopefully won't either.

    C.
     
    Last edited:
    #17
    Idaho CTD said:
    I have a .30-.378IMP. that does 4000+ FPS with 150 Ballistic Tips in a 30" Hart 10 twist barrel. I'd say with a 17" twist, 25gr lighter bullet, and 2" more barrel you should hit your goal. I'd do a improved version if it was me though.
    Click to expand...

    What powder? More curiosity. Please detail the improvement. Ackley or Gibbs shoulder maybe?
     
    #26
    Got a vid couple years back of Richard Franklin vaporizing 'chucks with a 1:14 twist .300WSM. 110Vmax @ ~4K, IIRC?
    Anyhoo, it was an impressive display, so this monster you've built should be a fuggin' hoot to mess with!!!

    Have fun & keep this one updated, please...
     
    #29
    wildcats said:
    Chad,is there a jacketed 125gr that will stay together at those speeds?
    Or are you going to be using sollids?
    Click to expand...
    the bullets biggest enemy is RPM more than velocity, which is why he's using the 17 twist. Although I'm sure they've never tested them at that velocity, so guess we'll find out if they can handle it.

    Sent from my GS5 on Tapatalk
     
    #30
    Turd in the Pool said:
    What powder? More curiosity. Please detail the improvement. Ackley or Gibbs shoulder maybe?
    Click to expand...

    It has a caliber worth of neck length and a 35 degree shoulder. I can't remember what I spec'd for shoulder diameter but it didn't have a whole lot of taper. I was using WC872 for powder and about 128-130 grains of it. I think I was shooting 210gr Bergers 3650fps, 185 Bergers at 3800fps, and 165NBT's at 3900fps. I left my loading book up at my camper over the weekend so I can't say 100% but I bet I'm close. When I built it about 15 years ago there wasn't much for slow powder but I'm not sure even now that R-33 and some of the others are slow enough for it.
     
    #32
    Today I exploited the elderly some more...

    A good friend came by and he's been the one working up loads for this thing as I just don't have the time. He made it very clear that he wouldn't be shooting the new barrel until I had a brake made up for it. So, soon as I get a spare moment or a late night I'll knock one out for it.

    Time'll tell...


    FWIW:

    This isn't the first rifle I've owned chambered in this cartridge. I started this little pet project almost 10 years ago with another gun. That one got me 4375fps on a 1:12 twist Lilja that was 29" when loading 125 ballistic tips. This was according to CORBON ammunition's test tunnel Chronograph.

    So, With any luck and the newer powders out there maybe the little buggers will reach the goal.

    Fun stuff.

    C.
     
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