7mm vs. 7mm ultra mag?

Discussion in 'Long Range Hunting & Shooting' started by tknc, Feb 19, 2009.

  1. tknc

    tknc New Member

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    Hey guys , I'm fairly new to hunting I'm in my ealier 20's and I have just taken on the deer hunting a couple of years ago. I've been very intrested to find out what would be the better long range cartriage. I've recently owned a 7mm remington mag and had some good success with it. Being new to hunting the furthest i've shot a deer was about a 100 yards (which is probably a joke to some of you older and more expericened hunters lol) anyways I'm about to go out west in a couple of years and looking to make some considerably longer shots after some practice. I was wondering which chamber you would recommend. I've just picked up a sendro sfII 7mm ultra mag with a 9 1/2" twist ratio. I've heard some good things and some bad things about the 7mm ultra mag. Should I work the 7mm ultra mag or stick with the 7mm mag I have. Also, if you guys have any other suggetions on good chambers to use re-ply back. I have money to work with, so any other suggestions on a different caliber would be taken in great consideration.
     
  2. elkstalker300

    elkstalker300 Well-Known Member

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    I have both a 7mm rum and a 300 rum, the 300 is the orginal sendero model and the 7mm is a sporter model, BDL I think. I havent even shot the 7mm because I love the 300 so much, out to 1100 yds its deadly :) yesterday I dug the 7mm out of the mothballs to get her cleaned up to start shooting alittle but doubt I will ever like it as much as I do my 300
     

  3. J E Custom

    J E Custom Well-Known Member

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  4. bwaites

    bwaites Well-Known Member

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  5. 338 LEGEND

    338 LEGEND Well-Known Member

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    Use the 7 ultra it is very very very flat shooting, and no belt. Load a 160 or 180 gr bullet. The 7 rem mag is like your moms station wagon ( out dated).
     
  6. MontanaRifleman

    MontanaRifleman Well-Known Member

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    tknc, if you crunch the numbers, it's hard to beat the 7mm RUM. I've shot a 7mm RM for many years and it's a great cartridge, but IMO it's an 800-900 yd hunting rifle. The RUM will get you well past 1K maybe 1300-1400 yds depending on load, elevation etc. If I had a choice between the two, the RUM would get the nod. In fact, I've been considering the 7mm RUM vs the 300 RUM and just recently picked the 300 because this particular rfile is a proven tack driver. Otherwise, I was leaning to the 7mm. If I get another rifle, it will likely be the 7mm RUM.

    I'm not sure what bad you've read about the 7mm RUM but I cant think of any. Barrels burn out fairly quick, but that's the same for any of the 7mm mags.

    If you like open country, you will like the West.

    Good hunting,

    Mark
     
  7. J E Custom

    J E Custom Well-Known Member

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    ON the barrel burn out issue.

    Any over bored cartrige will burn out faster than a standard one.

    P O Ackley did a lot of testing on this problem and so did the military they both came to the
    same conclusions that any round that exceeded 3000 ft/sec and was over bored (Like most
    Magnums ) would be harder on barrels.

    Powder erosion is the biggest problem with over bored rounds because a lot of powder gets
    pushed out of the chamber and against the throat that has not burned yet.

    Ball powder was developed to minimize this problem because it was though that the shape
    was easer on the throat.

    As far as the throat erosion of the 7mmRUM it will probably last 12 to 1500 rounds with good
    loading and cleaning practices ( A lifetime of hunting ).

    The heaver bullets will help with barrel life ( Lower velocity and more complete burn of
    powders ) plus better BC for long range .

    The big 7mmRUM was made for big bullets and will amaze you how accurate it is when set
    up with the right powder and bullet combo.

    J E CUSTOM
     
  8. MontanaRifleman

    MontanaRifleman Well-Known Member

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    J E, you are more knowledgeble on the subject than I am, and for the most part I completely agree with you. But I have read numereous posts that the 300 WSM shows quite long barrel life, 4000+ rounds, and that the 7mm WSM which is very close to the same case has short barrel life 1000-2000 rounds. I find that very interesting. I wonder if that translates over to the RUM cartridges in 7mm and 300? From what I've read it doesn't seem to, at least not to a significant affect. My guess is that a 300 Rum shooting a 210 bullet will probaly slightly out last a 7mm RUM shooting a 180 bullet under similar conditions? Just a guess. It's been my impression that smaller bores in equal size cases burn out faster because they are concentrating that fire power in a smaler area. That may be an overly simplistic view of it. There is probably mor to it. And your assertion that shooting heavier bullets at lower velocities and better powder burn makes sense,

    Interestingly, GS claims their bullet design increases velocity withou increasing pressure and their design also facilitates the burn of powder over a longer and larger area of the bore resulting in less throat burning and overall cooler shooting temps.

    GS CUSTOM BULLETS - Barrel Wear
     
  9. Buffalobob

    Buffalobob Writers Guild

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    Well being as you already have both a 7 Rem Mag and a 7 RUM and a few extra pennies laying around the situation seems to me to be like this.

    Buy a reloading set and learn to reload.

    Take a few more pennies and buy expensive optics such as rifle scopes, rangefinders, binoculars and spotting scope. Each one of those items will run very near $1K, so that is going to be quite a pile of pennies.

    Use the 7 Rem mag for a practice rifle until you burn the barrel out and then use the action for a custom rifle.

    Once you have developed some skill reloading then develop a good long range load for the 7 RUM and then set it aside for hunting only, do not use it for practice.

    If either of the rifles proves to be inaccurate then you are in a different ball game.
     
  10. J E Custom

    J E Custom Well-Known Member

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    Thanks for the complements but there is a lot more that I can learn before I go to the Happy
    hunting ground. and I can only speak from over 50 years of experance and you are right
    about smaller bullets and bigger cases.

    Hear is an example= Take a 375 H&H with a 275gr bullet(The standard bullet used) and place
    70grs of powder behind it and you will get 2600 ft/sec velocity and who knows how many
    rounds you can run through it 15000+.

    Now take the same 375 H&H case and neck it down to 7 mm and blow the shoulder out and
    forward into a wildcat like the 7mm STW ( most belted wildcats started life as a 375 and were
    changed to personalize them ) and you have a barrel burner because you have made it into
    an over boar cartrige and barrel life will not be as long.

    Barrel life is determined by many factors so to say a barrel only has 1000 rounds in it
    would be unfair and just a guess under the worst case scenario.

    I would think that the 7 WSM would have less barrel life than a 300 WSM but not twice or three
    times less because of the smaller and faster bullets.

    If a barrel is kept clean and carbon is removed as often as possible barrel life will be improved
    and accuracy maintained longer.

    The 308 is a prime example of the reverse because most match shooters use the 168gr + bullets
    and velocity is 26 to 2800 ft/sec using around 42grs of powder and barrels last 20,000 +rounds
    before any loss of accuracy.

    The first thing I do when a friend brings me his favorite rifle complaining about how the barrel
    is shot out and will not group any more is give it a GOOD back to bare metal CLEANING and
    most of the time they shoot just like they used to.

    And be carefull not to believe everthing you read about claimes of unbelievable high BCs,
    velocites,Barrel life ETC because if it seems to good to be true it probably is not true.

    By the way ANY Banded Bullet of the same weight and dia. will be slightly faster than a full
    bore dia. bullet because of less bearing surface just like flat based bullets have longer
    bodys than boat tailed bullets of the same weight and dia. increasing bearing surface
    and slowing velocity slightly (a vary small % ) so this is not something new and wonderful
    and may have a downside in some applications.

    J E CUSTOM
     
    Last edited: Feb 21, 2009
  11. älg

    älg Well-Known Member

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    Re barrel burners .- <I think one can get a very general but fair idea for comparisons if dividing powder grains/caliber.

    i.e. 90 grains/ 7 mm cartridge: 12,86
    65 grains/ 7mm cartridge: 9,28

    It does not give absolute figures but I thin k can be an easy rule of thumb for a fast comparison. Of course it does not bear in mind bearing surface, speed, etc.. but does the job.

    Re. the 7rm- it is well behind the 7rum but even being an oldie I would not treat it as useless. There´s many swearing for the 7wsm now and the 7rm is equally if nor more capable.
     
  12. LewisH

    LewisH Well-Known Member

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    I chose the 7 STW because it is (1) 7mm for the high bc and sectional density of the heavier .284 bullets (like 180gr Bergers). (2) Reputation for excellent accuracy. (3) A step up in power from the venerable 7 Rem. Mag., or the new 7 WSM.

    Yes, it's overbore (inefficient), but not as bad as the RUM; and is reported to be less finicky to load for.

    If I hankered for an even more powerful 7mm, I'd skip the RUM and go straight to the 7 Allen Magnum, which enjoys an outstanding reputation, and is formed from the very strong 338 Lapua brass (much stronger than Remington brass).
     
  13. tknc

    tknc New Member

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    Thanks to all who replied to my post. I recieved very knowledgalbe information from everyone that posted. I'll do my very best to apply this knowledge out in the field. Thanks to all and happy hunting.
     
  14. MontanaRifleman

    MontanaRifleman Well-Known Member

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    JE, I hear ya on this, but there are guys shooting these bullets with significantly higher than *normal* velocities. The BC's are in question, but as I said in another thread, the proof will or wont be in the pudding. so I figure I'll load up a few and send them down range :)

    Once again, I agree with you in theory, but working up loads for the smooth E-Tip and banded TTSX I found no significant difference in velocity. Now that may and probably is just my rifle or some other variable. but the GS's do seem to have something going for them in the velocity department. I would say the jury is still out until I see it for myself, but I like being an optimist when it comes to ballistics :)