375 vs 338

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 338 bruce, Jan 5, 2009.

  1. 338 bruce

    338 bruce Well-Known Member

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    does the 375 350 gn smk have any long range advantage vs the 338 300 gn? and has anyone hunted with the 375 350 smk ( terminal perf on game)?
     
  2. Down Under Hunter

    Down Under Hunter Well-Known Member

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    Bruce,

    From what I have read so far it does if your talking 1600 yards and beyond.

    That 350 smk loaded to 3300 fps out of the 375/048 imp versions would be hard to beat.

    It simply smokes the 50 BMG, 408 CT and the BARRET 416 with down range whack !

    I am very interested to find out some more about this round and have PM'd Kirby to talk about the 375 AM which I am quessing may be hottest of the bunch.

    There is a projo from Hooker Tactical at 350 grn that is CNC turned with a dopplar BC of 1.12 !!

    Dont know how they go on game though ? Probably rip a big hole from a tumbling projo going through ?

    If the 350 smk is anything like the 300 smk I shoot now, I'm sure it would be a killer.

    I spoke with Bobby Lawton this morning and he told me he has shot the round out to 3000 yards and in a 5mph full value wind you only need 20 moa windage ! 20 moa only !

    I seem to remeber Kirby thought it may potentially be the greatest of them all for Extreme range ballistics with the right projectiles ? Maybe ?

    Cheers

    DUH
     

  3. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Ballistically, they are so close it would be hard to tell one apart from the other if launched at the same muzzle velocity. Sierra lists the BC of the 300 gr SMK as 0.768

    In my testing with my 338 AM, I have to use 0.81 to get the drop chart to match up perfectly with the actual bullet flight of the 300 gr SMK.

    In my testing of my 375 AM, using the 350 gr bullet, I was able to drive them to roughly the same velocity of the 300 gr in the 338 AM, around 3300 fps.

    Trajectory for one can be used for the other they are that close. Only real difference I have see is that the 375 has a larger frontal area and higher kenetic energy payload and seems to hit harder.

    I have only tested these bullets out to around a mile. I can not comment about shooting them to 3000 yards but I can say that I have tested the 300 gr SMK in 338 extensively and at my altitude of around 3500 ft, around 2800 yards is max range with super sonic velocity. Past that, accuracy goes to hell because the bullets become unstable.

    It may be possible but I find it unlikely that the 350 gr SMK would be consistant out to 3000 yards as it will drop below super sonic velocity well short of that range and I have yet to see a SMK perform well after dropping out of super sonic velocity.
     
  4. 338 bruce

    338 bruce Well-Known Member

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    thanks, thats kind of what i was thinking, the 375 hitting harder at beyond about 1200 yds on elk. i am going to replace the barrel on my rem sendero, probably 375 rum and maybe 30 inch. i read that rocky mnt bullet is working a .375 359-385gn hunting bullet with a pretty high bc .8-1.0 .
     
  5. ZSteinle

    ZSteinle Well-Known Member

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    Where are you seeing these 375 SMK's i can't seem to find them anywhere?
     
  6. Down Under Hunter

    Down Under Hunter Well-Known Member

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    G'day mate !

    I think they are 350 not 375 grn for the 375 cal. Sierra make them and I am told you can get them from Jamison, but they are not in Sierras catalogue currently. I was told they were being made exclusively for CHEYTAC but guys are getting them !

    DUH
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    yes, the 350 gr SMK was made specifically for Chey Tac Industries and Jamison International are the ones taking care of distribution.

    In my testing, BC seems to be in the .770-.780 range. Pretty close to what Jamison told me which is really close to what Sierra lists the 300 gr 338 SMK BC at.

    As far as this bullet in the 375 RUM class chamberings. I think it will work fine, expect your velocity output to drop, perhaps more then many would expect. Also realize that the 375 bore diameter is not overly barrel length dependant so throwing more barrel length on a rifle WILL increase velocity but as the bore diameter increases, the increased velocity per inch of added barrel length REALLY drops off.

    That is a minor downside, the good side, this caliber does very well in shorter barrels!!! ITs a relatively high expansion ratio bore diameter which allows faster powders to be used and there is less baring surface on the bullet to the bore. Some feel its simply the larger area at the base of the bullet, whatever it is, the 375 will do very well in shorter barrels.

    When talking about even heavier bullets, I personally feel that the ballistic advantage of a 375 to 385 gr bullet in 375 will be wasted to some degree in chamberings such as the RUM. The reason is simply the velocity potential will be limited so that the lighter bullets will likely do just as well if not better then the ultra heavy custom bullets that may be coming on the market soon.

    They will certainly work and velocity is certainly not the end all of ballistic performance, that is for sure. Wind drift is the real killer and that will be an advantage of an ultra high BC bullet but again, I believe anything much heavier then 350 gr is getting pretty big for the RUM class chamberings and smaller.

    One example of this, I tested the 300 gr SMK against the 350 gr ULD RBBT in my 338 Allen Magnum. Because of velocity advantage, the lighter bullet had better ballistics out to around 1500 yards so if your not going to be shooting past 1500 yards, there is really no advantage for either bullet.

    I feel it may be the same in the 375 as well but I really want to get my hands on a 385 gr class bullet in the 408 based wildcats.
     
  8. 338 bruce

    338 bruce Well-Known Member

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    the loading data i have seen puts the 375 rum shooting a 300 gn bullet 3000 fps and 350 gn at 2800 with a 24 inch barrel. a 30 inch barrel wont do better? the 338 edge shoots a 300 gn bullet at 2900-3000? these are the two choices i was looking at, thanks bruce
     
  9. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I would say the edge would get you 2800-2850 fps in a 30" barrel with the 350 gr bullet, POSSIBLY.

    From my testing, a 338 and a 375 with the same case capacity will drive a 300 gr SMK and a 350 gr SMK to roughly the same velocity respectively. For example, in a 30" barrel, the 338 Edge will get you around 2850 fps, the 375 RUM will likely get you around 2800 fps in a 30" barrel.

    I can not imagine any way that you could get that velocity in a 24" barrel without running extreme pressures.

    The 375 RUM I used to have, had a 27" barrel and it would drive the 300 gr bullet weights to 2900 fps tops. At that level primer pockets would loosen up at around 4 firings which tells me I should not push things any harder.

    Basically, if you like the Edge with a 300 gr SMK, the 375 RUM with the 350 gr bullet will do basically the same thing ballistically but with a larger frontal area bullet and higher kenetic energy payload.

    Also remember recoil will be noticably more for the 375. Adding 50 grains of bullet weight at roughly the same velocity will make a difference on how the rifle comes back at you.
     
  10. Booney

    Booney Well-Known Member

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    I have a stock 375Rum. I know for a fact there is no way you are shooting a 300gr 3000fps out of a 24in tube. You have to push it hard to get that speed with a 260gr.
     
  11. 338 bruce

    338 bruce Well-Known Member

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    is there a larger case that can be chambered for 375 cal in the rem 700 sendaro action? can i replace the extractor with something stronger like a ruger claw?
     
  12. ought6plinker

    ought6plinker Member

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    I had wondered what the 375RUM would do with the 350 in a 30''ish bbl, I like when I don't even have to ask to get my answers! Powder is a question I do have with larger bore but heavier bullet would a 375rum/350 combo also use H1000 class powders?? any notes you could share? good huntin=) forgot to ask will a 1in12 twist stabilize the 350smk at rum velocitys?
     
    Last edited: Jan 12, 2009