Featured Help choosing a barrel length, contour and twist for a 300 Norma Magnum

Discussion in 'Long Range Hunting & Shooting' started by KenParker, Nov 3, 2018.

  1. KenParker

    KenParker Member

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    Oct 24, 2018
    Hello,

    I'm new to the forum and to the long range shooting, I'm a hunter from Switzerland.

    I decide to get close to the reloading ammunition and the long range shooting.
    For doing that I choose to build my first full custom rifle (I already own an half custom, 325 Savage):

    I'm a bit on a budget since I have to buy the rifle and the reloading equipment.

    I make research on internet (probably not the best way to get all right), but I learn quite a bit.
    After couple weeks of research I finally find my composition and my caliber:

    300 Norma Magnum

    - Kelbly Atlas Tactical Long Action
    - Timney Trigger 2 sage Calvin Elite
    - Hollands Muzzle Brake
    - Leupold VX 6 HD 4-24x52 (remove from the 325 WSM)
    - March gen II scope rings

    - Stock?? (Still in doubt, because in Europe, McMillan and Manners are expensive!! maybe a Bell&Carlson, GRS Bifrost or I'm open to suggestion)

    - Lothar Walther barrel

    I choose Lothar Walther barrel because they're in Europe, so much less taxes.

    I'm gonna use this rifle mostly at the range (not even long range, 300 meters :) hopefully couple times a years 600-800 meters) and sometimes to hunt. I'll be shooting 20-30 rounds a day!

    I plan to use 210 gr VLD Hunting and/or 230 gr Hybrid Target.

    Now my question:

    Barrel contour? Like I said I would to shoot 10-20 rounds without worrying about the heating barrel.
    Barrel length? 26" or 28"
    Barrel twist?

    Like I said before I'm completely new to this world, so don't laugh to much and I'm open to any suggestion.

    So far I only ordered the Action.

    Thank you

    P.S: I hope my english is not that bad!
     
  2. NEMTHunter

    NEMTHunter Well-Known Member

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    Feb 16, 2014
    Howdy and welcome! By the way I think your English is fine! I understood it!.


    10-20 shots back to back without a heating problem is going to be a problem I feel. I would not shoot it more then 3 or 5 shots before letting it cool. Barrel life would be a lot better.

    Contour: If weight is not a problem. I would do a heavy Varmint or Palma. Or you could go custom. A simple one would be keep the shank about 5 inches long then strait tapper it to .875 or .900 at the muzzle.

    Barrel length: 28" better use of the selected cartridge and powder capacity.

    Twist: 1:9 with 5R CUT rifling.
     
    shawnb likes this.
  3. KenParker

    KenParker Member

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    Thank you for the quick answer.

    Then I follow your advice, 5 shot max :)

    I will be probably choose "Standard Heavy Varmit", but just for curiosity if I would like something less heavy?
    (The whole gun with scope will be 14-16lbs (6.5kg to 7.5kg) depending on the stock)

    How important it's the 5R CUT rifling? Make so much difference to 6?

    Because it's seem the Lothar Walther has 6 groove!
     
  4. KyCarl

    KyCarl Well-Known Member

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    May 10, 2017
    I have a 300 WM in a McMillan A-5 stock and an Obermeyer 26" MTU couture 1:10 twist
    5R cut rifling..It almost broke itself in!
    and it ROCKS! It weighs a lot but the recoil is not bad at all! I never noticed heat issues
    but I shoot and wait? It shoots about .400 for 3 shots with Federal Gold Medal match
    ammo..With 190 grain SMK bullets. I think I can close that up with good reloads?
     
    Last edited: Nov 4, 2018
  5. sable tireur

    sable tireur Well-Known Member

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    KenParker,

    Welcome to LRH! Your English is fine, I understood everything you wrote.:)

    Just a couple of observations similar to some above.

    Shooting long strings of fire will shorten your barrel life. Keeping your strings to 3-5 shots then a cool down period is a good idea.

    If your range is usually about 300 meters and hunting distances, I might reconsider the cartridge choice. I shoot the .300 Norma Mag. a lot and it is suited to extended longer ranges and heavy body animals. You can have a milder cartridge for both hunting and 300 meters without the recoil of the Norma Mag. However, I will never deny a man his choice of cartridges and bullets when it comes down to a choice of what he wants to use.

    I have a soft spot for Lothar Walther barrels here in the US because they have provided me with good service and a fine product for years. I met Woody Woodall many years ago at one of our big trade shows. We have had several excellent conversations. There is nothing wrong with the standard 6-groove rifling since prior to just a few years ago that's all we had available. The 5R cut rifling is in high demand currently for most types of shooting and many cartridges. It has become a pat (standard) answer to write '5R' since it's a common choice.

    L-W 6-groove pull button rifling has held up on the rifles I used them on and some have been extremely accurate. They have a Medium Varmint Sporter #2140 which should save a little weight yet give you confidence of a heavier barrel. I've gone as light as a #1450 with good results for hunting rifles.

    Regards.
     
    alcesgigas likes this.
  6. KenParker

    KenParker Member

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    Sable tireur:

    I choose 300 Norma Magnum because I wanted a caliber for long range as well,
    but in Switzerland there're not many events to shoot long range.
    Digging in internet I found this caliber, is a bit performant than 300WM and less recoil than a 338 LP.
    I shoot my 325WSM without muzzle brake and a Ruger Heim (really light) on 8x68 that kick like a mule, I hope that the 300 Norma Magnum with a muzzle brake won't be that bad!
    I gonna shoot Red Deer (to big caliber?)

    I hope that I will not regret my choice!! Since I already order the action.

    So I'll be just fine if I'll have a 6 groove? Instead the latest "trend" 5R?
     
  7. cjuve

    cjuve Well-Known Member

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    I am in the process of of a similar build, 300 Norma Imp. Here is the list of my parts.

    Kelbly Atlas Tactical
    McMillian Game Hunter w/Edge Tech
    Trigger-tech Diamond
    Proof research sendero 1:9 26”
    5 port mag muscle brake
    Wyatts extended box mag.

    So far I am pretty impressed with the Kelbly. The only issue that I have is that the trigger hanger interferes with a 4.0 wyatts box. I am sure I can get it to work so more of an annoyance than anything
     
  8. NEMTHunter

    NEMTHunter Well-Known Member

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    Howdy,

    What you could do is get on the Pac-nor barrel web sight and design the barrel you want and their program will tell you what its weight will be.

    Here is a link to the calculator. http://pac-nor.com/cgi-bin/bweight.cgi

    As for the 6 groove I am not the guy to ask. All my 30 cals have 5R cut rifling. I do know from what others that test have said that 5R is not as hard on the jacket of bullets with faster twist and higher speeds.

    I will let other deal with that question as I am NOT the guy to ask their.

    As a side not I just built a gun that is 16.5 pounds ready to shoot with the scope, muzzle brake and by-pod. The barrel is 1.2 inches for 6 inches then from there strait tapper to .875 at the muzzle. The barrel is 32 inches long. The stock is a heavy laminate.
     
  9. WildRose

    WildRose Well-Known Member

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    To take full advantage of your case capacity I'd say 28-30" in length and have at least a light palma contour.

    If you're shooting more than three rounds in a string in less that 2 minutes no matter what you do heat is going to start to build.

    Long shot strings also lead to rapid throat erosion as well.

    My rule is no more than 3 shots in 2 minutes at the bench and allow it to cool down for at least a couple of minutes between strings. It can be boring and make for long days at the range but in the long run it will save you a lot of time and money.
     
  10. KenParker

    KenParker Member

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    I have a question what's the difference between a
    "light palma contour" (28inch) that weight 2.27 kg (5lbs)
    and a
    "standard heavy varmint" that weight 2.63 kg (5.8lbs).

    I guess less heating problem... More accurate? And longer life?

    Another question, still on the groove:
    it's accurate the 6 groove as well or I really need to look for a 5R cut?

    If a 6 groove is made proper should be accurate as well?
     
  11. WildRose

    WildRose Well-Known Member

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    There was a lot of voodoo preached about the magical accuracy of the 5R along with increased velocity. In truth though what has proven to be true is that with equal quality work they are basically equal in both respects.

    They are all going to get hot and suffer accuracy issues with long shot strings in any magnum caliber. That is why typically bench rest shooters shoot small capacity cartridges where they can.

    Just don't shoot it hot and keep shooting or accuracy and barrel/throat life will suffer.
     
    alcesgigas likes this.
  12. sable tireur

    sable tireur Well-Known Member

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    The world was shooting little tiny groups with 4- and 6-groove barrels long before Boots Obermeyer 'created' the 5R rifling style. So, in my opinion, the barrels will be equal in accuracy and barrel life. The 5R rifling tends to clean up a little easier and is less aggressive on thin bullet jackets.

    "The 5r rifling concept is nothing new. It was developed by the Russians in WWII. Boots Obermeyer resurrected and refined it and now it is taking off in popularity because it has a couple of different advantages over the standard 6-groove rifling. The angle of the sides of the lands is one of the biggest differences...along with the fact that because there are 5 grooves instead of 6, no two grooves are directly opposite each other. One advantage is that there is less chance of bullet deformation (which can result in better accuracy), the other is in the fact that because of the angle of the sides of the lands, fouling doesn't accumulate nearly as much. That results in more sustained accuracy in situations where the barrel is subjected to more or less continuous firing over a long period of time without cleaning.....such as in a combat environment. The U.S. Army uses 5r barrels on the M24 platform, while the U.S. Marine Corps is still using a 6-groove rifling for the M-40 platform."
     
    alcesgigas and xsn10s like this.
  13. KenParker

    KenParker Member

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    Oct 24, 2018
    Thank you for your time and all the answers!!

    Now I'm ready to buy the barrel!
     
  14. KenParker

    KenParker Member

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    Oct 24, 2018
    I just got another question:

    I see some people have a 1:8 twist instead of 1:9, I read that is faster for heavier bullet(200 and up) but if you want to shoot lighter bullet is better the 1:9 that's correct?

    I just found out that there's an association nearby that shoot up to 500m/800m monthly so I'll not stock to 300 range :)

    I have question about Manners stock (with Kelbly Long Action), I should post a new tread?