7mm UM project need advise

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 308 nate, Jul 6, 2004.

  1. 308 nate

    308 nate Well-Known Member

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    question #1 what velocity can I expect with a 180 grain Berger or JLK with a 36" barrel? my guestemation would be 3500fps. Am I way off?
    question #2
    I'm undecided on what barrel to buy.The barrel is going to be 1.250 for 14" And then straight taper to 1" at 36 "
    here are the quotes I got
    Krieger $372
    Lilja $371
    Pac-nor $345
    I'm leaning twords the Krieger but what do you guys feel is best for the money
    so here is the plan. Savage action(ya' I know I'm a Savage fan) 36" barrel
    straight 1.250 bull for 14" then i'm going to make a liquide cooled barrel block 12" in lenghth,then cast an alluminum bench rest stock.(we have a small foundry) If the stock turns out the way I plan I may end up making more. All thought and ideas welcome.This is an experiment I am building for my father in-law.And when it is completed I'll post pictures and a review. [​IMG]
    thanks to all you guys who make this a great long range hunting site!And thanks Len for starting it. i stumbled onto this site about 5 months ago and have visited here every day since. [​IMG]
     
  2. chris matthews

    chris matthews Well-Known Member

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    Question #1 It might but seems a bit much. Hodgdon lists 3000 fps out of a 26" so 10 more could get you 250-500 depending on what "rule of thumb" you use for velocity gains. Some say 25, some 50 even heard a few say 100fps per inch gain.
    Question #2 Krieger 7mms have been good to Len and I, however so has Schneider 7mm polyganol or the Broughtons are the up and coming new guys on the block. Lilja's are good barrels, but I haven't used any of his 7s. Have had so-so luck with Pac-Nors but not really hot or cold about them. Alot of help huh? All are good and if put together properly will shoot good.
     

  3. speedbump

    speedbump Well-Known Member

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    I'm getting a comfortable 3,360 out of a 30" Krieger in 1:9 twist. 176gr Cauterucios over 5010 pulldown, R-P cases & a FC215M or an FC 210M seated .005" into the lands. You should be in the 3,500 fps range with a 36 incher.

    I like the Krieger, but have a 30" Pacnor 3-groove waiting for the Krieger's throat to be mauled (it's been re-throated once, down to @28.5" now). The Krieger is an un-compensated heavy Palma taper, FWIW. [​IMG]
     
  4. 308 nate

    308 nate Well-Known Member

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    also forgot to mention 1-9 twist or would I be better of with a 1-9.5 or 1-10 at that speed?
    Also how will the bullets I mentioned stand up at say 3400-3500fps?
    chris thanks for the other barrel suggestion I will give them a call.
    Is poilganol rifling better for throat erosion ?
    speebump thanks for the info. [​IMG]
     
  5. chris matthews

    chris matthews Well-Known Member

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    Yes, the poly handles throat erosion pretty good.
    I don't think the Bergers can handle that speed. The JLKs might but the Cauterucios definitely will and don't forget about the new 175 MK.
     
  6. speedbump

    speedbump Well-Known Member

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    Nate/Chris,

    I talked with Walt Berger a few years ago about the 180s & RUM velocities. He said another bullet with a tougher jacket would be advisable. That has since been confirmed by others. Nice fella and HONEST.

    I haven't tried the Sierra 175s yet.