Which 7mm???

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by ahudler, Oct 23, 2008.

  1. ahudler

    ahudler New Member

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    I need help deciding which 7mm to build. I am looking to build an accurate long range hunting rifle, and am stuck between the the 7mm mag, 7mm stw, and possibly the 7mm rum. I currently have a 300 wm, and a 270 Weatherby mag, but this will be my first rifle "build". I already have a Remington LA for the platform. I am planning on using the Berger 168 VLD's because of the high BC's.

    My questions/concerns are... Which is going to be the "easiest" to reload and tune, best barrel life, feeding problems (AOL/mag length), etc. I am not worried about kick, I just want a very accurate 800-1000 yard rifle.

    Any and all thoughts are welcome...
     
  2. gamedog

    gamedog Well-Known Member

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    I'm in the exact same shoes.
    I've decided on the 7 Rem Mag.
     

  3. Derek M.

    Derek M. Well-Known Member

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    7mm Rem Mag. I'm using 72.5gr Retumbo with the 168 VLD.
     
  4. kiwi3006

    kiwi3006 Well-Known Member

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    I have just done this, I went with the 7mm mag for the following reasons. I didn't want a muzzle break as this will be a bush stalking rifle as well. So 7 mm mag won because of less recoil.
    In NZ getting brass for 7mm mag is easier than 7 stw.
    7 mm mag easily fits into a long action with projectile seated right out. 7 stw might not fit if you want the projectiles right on/in the lands, as with the VLD projectiles.
    My hunting partner already had a 7mm mag.

    I am really happy with how it worked out. Here is a link to what I did http://www.longrangehunting.com/forums/f19/re-barrel-7mm-rem-mag-33483/

    Stu.
     
  5. Derek M.

    Derek M. Well-Known Member

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    If you have any doubt about the old 7 rem mag and a 168 VLD, here's a video that's been posted before:

    YouTube - long range

    I discussed this video with the folks at botw when I first saw it and was told that John Burns shot a modified 7STW and the guy with him was using the 7 rem mag. I've also been told that since this video, Mr. Burns has gone back to the 7 rem mag as it is a more "user friendly" caliber.
     
  6. ahudler

    ahudler New Member

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    That is excactly what I have been looking at. I researched for some time, and it seems that for the "nominal" gains by the STW, brass and OAL issues are greatly diminished using the 7mm mag.

    Does anyone here have an STW that is magazine fed using 168 VLD's? I was thinking that if I went that route, and had the barrel and throat cut for a specific AOL in a longer mag box, that might work out??? It just seems to me so far that everything for the STW and RUM are much harder to find and dial in???
     
  7. ahudler

    ahudler New Member

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    Hey guys,

    I would also like your input on barrel length and contour. This will be a packing rifle, so I dont want it super heavy. What do you think about a fluted heavier barrel to help keep down the weight? Maybe 28" 1:9 twist???

    Thanks for all of your help
     
  8. 260shooter

    260shooter Well-Known Member

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    I'm getting parts together for a 7 REM Mag build. Using a 700 LA, old Sendero stock, 9 twist Broughton Sendero contour barrel, And a DE brake ( so my 10 yr old daughter can shoot it). All up, it should weigh 12-13 lbs with bipod. I too plan to shoot 168 Bergers.

    260
     
  9. AZShooter

    AZShooter Well-Known Member

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    I too have been looking at all the 7 mm options. Recently I bought two new 26" Rem takeoffs and had one chambered for the 7 RUM and the other for the 7 STW. Every component was indentical. Moly coated 168 Berger VLDs, RL-25, Fed 215 primer and virgin Rem brass. The 7 RUM beat the 7 STW by approx 50 fps with max loads. I concluded that the 7 RUM needs a longer barrel.

    I liked the 7STW so much that it stayed in that platform. The 168 VLD has a .160" jump to the rifling and fits the model 700's factory mag box and feeds perfectly. It also didn't require any alterations to the magazine feed rails like the RUM would have.


    To top this off, as I mentioned in an earlier thread, I had a friend give me a like new 20 yr old Interarms Mark X in 375 H and H. I already have a 375 Taylor so decided to rebarrel this rifle. The McMillan stock barrel channel is quite large. So...I ordered a 30" SS #7 profile Lilja 3 groove 1 in 7 twist barrel to shoot the 180 VLD! I then pondered long and hard as to which 7 magnum sized case to use.

    My friend Dan was struggling with a 7 STW CM barrel that went south with only 470 rnds through it. He had a long talk with Dave Kiff of Pacific Tool and Gauge. Dave told him the 7 STW was one of his favorite cartridges. Dave said he went through many barrels before he realized if you keep the bullet into the rifling instead of a jump it will last much longer. He said Dan could get around 1500 rounds of barrel life if he followed that approach. Dan ordered a reamer from Dave and also ordered a wyatts extended length box mag for his model 70.

    Based on this information and the difficulty in extended the length of the mauser style mag box, I opted to go with a 7 Rem Mag. I sent in a dummy to Dave with a lengthened OAL which will allow full engagement of the rifling with the 180 VLD and plenty of room to chase the rifling as it wears.

    I also have a lightweight (7 1/2 lb) Ruger M77 tang safety in 284 win. It has an extended mag box of 3". When barrel number 4 wears out I will have Dave make be a custom reamer for it too.

    As for fluting the barrel go for it! I have two #5 fluted liljas that are 27" and 28". The fluting looks good and does lighten it a bit. As for length, 26" would be great for a walkaround hunting rifle in either 7 mag or 7 STW. Lilja's standard finish length is 27" so I'd go with it as is. If I were to want a 7 RUM it would have to be at least 28" or longer or IMO not worth the extra blast, recoil and powder comsumption.

    I hope you have a great time with the entire process.
     
  10. Varmint Hunter

    Varmint Hunter Well-Known Member

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    I'd be interested in hearing the theory as to why you would get 3x the barrel life when loading into the lands.

    If anything you would expect loading into the rifling to cause increased pressure, increased heat and slightly longer bullet dwell time in the throat resulting in longer peak heat/pressure.

    Interesting
     
  11. AZShooter

    AZShooter Well-Known Member

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    I can only guess. Gasses passing the bullet as it goes through the freebore area? Actually there would be less powder involved with the bullet into the rifling to get equal pressure.

    I too would love to hear an explanation.
     
  12. ahudler

    ahudler New Member

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    Thanks for all of the input and replies. I have not totally made up my mind yet, but I am leaning towards the 7mm mag.

    As far as barrel length goes, I thought I read somewhere that the longer sleeker projectile from a 7mm needed a longer barrel (28") to properly stabilize the rounds? It sounds like some of you are happy with 26" barrels?? What about muzzle brakes...are they needed on a 7mm mag?
     
  13. MagMan

    MagMan Well-Known Member

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    I hope you plan on using the thick jacketed 180's. I've been down this road.....thin jacket bullets go poof. Although they shoot the 160 Accubonds well.

    8.5-9" twist works just fine for the 180's.
     
  14. MagMan

    MagMan Well-Known Member

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    Most likely not, but I like them. More than likely you's be able to see your hits at any distance. Which to me is more important than a bit of noise because I usually don't have a spotter.