Hello, newbie here with an itch to load 7mm R mag

Discussion in 'Long Range Hunting & Shooting' started by demented, Nov 26, 2009.

  1. demented

    demented Well-Known Member

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    I've got a Browning A-bolt 7mm Rmag that I've used for ten years with great results on whitetails out to 300 yards. I had decided to custom load a few cartridges with better bullets and try my hand at ranges to 400 yards. To my dismay, loads I've seen in three or four loading manuals show the performance of this cartridge to be far below what I'd hoped for, not much if any faster than a 30-06! Hard to believe all that case capacity won't push a 160 gr. bullet much faster than 2900fps. Never having loaded magnum cartridges I find myself wondering if my load manuals are ultra conservative or if the 7mm is one of the most overrated cartridges out there. 300 yards is no real test for any cartridge, I've downed many whitetails at this distance with a .308 Winchester. Thanks for any and all opinions, comments, etc. Oh, yeah, anyone got a "pet" load for a 160 grainer that'll chrono 3000, I's SURE like to see it! (I will start low and work up, SLOWLY, no suicidal tendencies here!)
     
  2. johnnyk

    johnnyk Well-Known Member

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    demented,
    Welcome to LRH. Glad to have you in the mix. I have shot the 7Mag for over a decade so I'm pretty familiar with it. I have been shooting the 150gn Ballistic Tip since I got my first 7Mag and it has never failed me. I am currently shooting 63.5gn of IMR4350/9.5M primer and last Sunday (48 deg) I chrono'd five shots that averaged 3234fps and the group was sub 1/2". Earlier testing when the temps were in the 75 deg range and velocity averaged 3240fps. CAUTION: This load is over max according to Nosler #6.
    I noticied that some of the reloading manuals, Hodgdon 2007 Annual Manual in particular, seemed to be playing down both the 7Mag and the .300WinMag. These two I noticied because I shoot them. Did the power and velocity just drop off for no reason? I don't think so. I feel it was because the gun industry was pushing the WSM's trying to convince the shooting public that these WSM's could achieve the velocity of their belted counterparts. They are close, but no cigar. I'll stick with the "belts" and jump off my soap-box.
    Look at Nosler's reloading data. It seems to be pretty spot on or very close most of the time. This is my first source and then I go to the others. This manual (#6) shows six loads for the 7mmRemMag 160gn bullet at 3000fps or more. JohnnyK.
     

  3. MontanaRifleman

    MontanaRifleman Well-Known Member

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    I also use to load for the 7mmRM back in the day. I also used IMR4350 for my pet load to push 160 gr partitons at about 3000 fps out of a 24" tube, although I dont remember the charge.

    I plan on doing some load development (if I can get some primers) with another 7RM I have fairly soon. I'll be using Retumbo, H1000 and RL17 with 160 AB's and 150 E-Tips. I think these powders should get the 160's well past 3000 fps.

    Mark
     
  4. 4bycamper

    4bycamper Well-Known Member

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    I handload and shoot a 7mm Rem Mag and get well over 3000 fps with 160 AB Noslers.

    This is a Remington SPS with a 24 inch barrel and a B & C stock and is my current elk rifle. I would put a longer, heavier barrel on it but it shoots too well to trash it. The longer barrel would provide somewhat higher velocity because I load slow burning powders like Ramshot Magnum and Accurate Mag Pro. These powders like the Fed 210 and Winchester WLR primers. The loads that shoot best in my rifle may not be the best in your rifle.

    If you start with the load data on these two websites and work your way up, one more grain of powder at a time, I think you'll find a load that will work for you.
    It's a fun project, enjoy.


    JM .02
     
  5. kiwi3006

    kiwi3006 Well-Known Member

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    I use 73 gr H1000, Federal 215 primer, Federal cases, Berger 168, 26" barrel and get a comfortable 3087 fps.
    I have read an article where they used a standard Rem 700 SPS with 26" barrel with Retumbo and 162 a-max to get over 3100 fps. They had a pressure gauge on the barrel and the Oehler 43 ballistic laboratory. The pressure was 60,000 psi.
    I believe some of the earlier comments were correct about maunfactureers deliberatly keeping pressures down in the 7mm mag.

    Stu.
     
  6. linksmechanic

    linksmechanic Well-Known Member

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    The first pound of retumbo I bought for the 7rm listed a 175 grn bullet at 2900. I still have the bottle somewhere. Now the bottles say 2800. I too believe something stinks in denmark with the current reloading data for the rm. Now don't go and do this but I get 3000 fps with no pressure with a 180 grn berger in the lands. This is with a 26" barrel. I'm using there listed max of 68 grns. Hodgdons data for a 162 grn. is around 2970 so I would think you could easily get there with a 160 with retumbo. Bergers data list's 3022 for a 168 with retumbo.
     
  7. demented

    demented Well-Known Member

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    Thanks to all for the advice, perspectives, information. I hope to be able to contribute a bit of info here but am sure that many here know far more than I ever will. I've loaded thousands of .308 and .223 as well a quite a few 30-06 and 270's over the years. As I said magnum loads are entirely new and to be honest their case size and capacity is a bit intimidating! I doubt magnums are any more dangerous than regular cartridge when reloaded but there is still that WOW factor thats hard to dismiss. One serious problem for me if and when I attempt to develop a load is that here in Podunk, finding several different powders to try will be a tad difficult. So far my powder selection is both 4831's and 4350, thats it. I barely located enough magnum primers to start, brass is in short supply (need more) and bullets are usually a backorder from Midway. Took me five months to get 500 Remington Cor-Loks to do some 30-30's I'd been wanting to do. Add all this plus the seemingly lack of performance of the 7mm and I had about decided it wasn't worth the effort.
     
  8. linksmechanic

    linksmechanic Well-Known Member

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    4831sc is a good powder and I initially used it in the beginning.
     
  9. BIG MO

    BIG MO Well-Known Member

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    The 7mm rem mag is a bad mammer jammer. Run a ballistics chart on a 180 berger @3000fps out to 1000yds. It is still cranking along @1800fps with 1300ftlbs of energy @1000. That is probably more than a .44mag at the muzzle. It is a tough round to beat without going ultra magnum.

    I am currently running RL 22 with the 180 Berger @3000fps with nice results. Depending on the nature of your particular rifle, it would not be unreasonable to find a load pushing a 160 pill to 3100 without abusing the brass.

    Personally, testing with different powders, bullets, etc searching for that load that puts a big smile on my face is probably my favorite part of the whole process. Enjoy the process. I promise you there is a load out there that you're Big 7 is going to love. Get after it!

    Welcome to Long Range Hunting. Its great to have you aboard!
     
  10. trueblue

    trueblue Well-Known Member

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    +1 on the Huskemaw scope with one piece Talley rings . I would also look at a light palma contour in 27" length. It will be plenty stiff enough, and save you about a 1/2 pound.