Rem 700, 7mm Rem Mag Re-Build, Pt 1

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by CB11WYO, Feb 22, 2013.

  1. CB11WYO

    CB11WYO Well-Known Member

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    So I just finished re-barreling my Remington 700. It "used to be" chambered in 300 RUM, 30" Hart Barrel and Shrewd Muzzle Brake. It never really performed better than 1 MOA (sure that's not THAT bad, but being a little obsessive and owning other "tack-drivers," I couldn't handle it any more :) ).

    So after 5 years of playin with it I up and ordered a 28" Broughton in 7mm. I did all the machine work, chambering, etc. myself...(first time I've attempted the process solo, but don't worry the "expert" was close by :) ) and yesterday just loaded up some 66, 67, 68, and 69 gr Retumbo loads with 180 gr Bergers to try out tomorrow (snow permitting). I'll keep ya posted on how it shoots! Keep your fingers crossed! :D:D:D
     

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  2. shawnb

    shawnb Well-Known Member

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    Nice rifle. Can't wait to hear how it shoots. What are the load components your using? Brass, primer, into/away from lands?

    I just got my hands on some of the 180 hybrids to try. They are shooting around 2960 out of my 26" lilja 9t. They held 1/2moa at 500yards test. They were 5 thou off at an oal length of 3.52". No pressure or nothing. Another member brentc is getting some pretty good numbers from his 28" barrel also.

    Keep us posted
     

  3. calib

    calib Well-Known Member

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    good looking gun, i enjoy doing my own work as much as i can do. feels good when you see those tight groups after your time you have invested putting the rite components together
     
  4. CB11WYO

    CB11WYO Well-Known Member

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    Nice! hope this one does as good...
    I'm starting with Reminton brass (they were free :) ), Federal Gold Medal Match Magnum Primers, bullets are just under 0.010" off the lands.

    How much and what kind of powder you using? if I may ask...
     
  5. shawnb

    shawnb Well-Known Member

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    Ya for sure...im using 69gr of h1000 with the 180 hybrids in win brass with f215m primers. This load was right at .5moa at 500. And i could prob push it to 70 grains as im not getting pressure signs yet. But they shot good here so ill leave it.

    Previous to trying those i was and still am going to shoot the 168 vld around 10 thou off with 70gr h1000 and same primer and casings. They are moving in the 3050 fps range and that is a verified velocity with no pressure also. I could run them higher to i think but again they shoot great there.

    I will test the hybrids out on some yotes and deer to see how they do. But i think Broz said he trusted them so if they hold out to a grand ill switch once i run out of the 168s. And ive got a lot of 168s.

    Now im not sure how your chamber is but if its throated long you should be able to push the envelope with retumbo in a 28" barrel and still have good brass life. From everything ive read you can use 1-2 extra grains of retumbo compare to h1000. And retumbo really seems to come together once it gets to a top end load just shy of max to give decent ES and SD.

    Work up like you are and be safe.
     
  6. 65WSM

    65WSM Well-Known Member

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    I am planning on building a 7mm magnum. I am leaning toward the 7mm Weatherby chamber to get a longer neck so I can partially size and still have some left to hold long bullets.

    I have experience with the 7mm Remington in Howa and Model 70 actions. I found the factory barrels were throated long and the magazines limiting. I always wanted to seat the bullets out further than the magazines (3.65 and 3.60 respectively) allow.

    What about magazine length with the 180 Bergers? What would you like to seat to if the magazine allowed? How far off the lands are you? Would the 175 Bergers at a higher velocity give a flatter trajectory?

    I plan to use VihtaVuori N-570 powder. Retumbo will get within about 60 fps in 6.5 WSM with 140gr.

    I bought 8 pounds of H-1000 when at that time Bruce Hodgdon brought it out. His plan was to provide a powder for 160 gr bullets in the 7mm Rem Mag. His original data showed 72 gr as max and several of us tried but found that unobtainable. After a phone call that Bruce took, I went back to Reloader 22 in place of H-1000 in the 7mm Remington and .264 Winchester. I was disappointed in the velocity. I gave it to some guys at the range I didn't like.
     
  7. shawnb

    shawnb Well-Known Member

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    Im about as far out as i want to be with the 180 hybrids.

    CB11WYO- how much does that gun weigh? And what contour did you end up going with. I really like that look.
     
  8. CB11WYO

    CB11WYO Well-Known Member

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    Well I just checked again and I'm currently 0.010" off the lands with a cartridge OAL of 3.425" and 1/4" of room still in the magazine, so I doubt I'll have problems there. This of course means those 180 grainers are stuffed deep in the cartridge but with 69 gr of Retumbo I can still feel the "shake" of the powder in a loaded round. So, depending on high-pressure signs, I still have room for more powder if necessary... We'll see...
     
  9. brentc

    brentc Well-Known Member

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    Shawn, what is your ogive length with the hybrids?
     
  10. shawnb

    shawnb Well-Known Member

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    I honestley dont even know. I have the rcbs mic tool and im not sure if that can give the measurement. And im guessing my velocity is a bit faster. My trued velocities always seem yo be a little faster than what my chrono spits out.
     
  11. CB11WYO

    CB11WYO Well-Known Member

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    I honestly can't remember the exact contour, it finishes at .750" at 28". Its a heavier contour than the old barrel and will hopefully shoot better too. On the digital bathroom scale she read 10.8 lbs, no bipod or ammo.
     
  12. CB11WYO

    CB11WYO Well-Known Member

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    Alright guys so I got out to shoot this morning! About 25 degrees, light snow falling, and slight breeze from 3 o'clock.

    I started with 3 rounds loaded with 66 gr Retumbo to foul the barrel and make sure the scope was on. (FYI all shooting was done at 100 yards) Then proceeded to shoot four, 4 shot groups of 66gr, 67gr, 68gr, and 69gr Retumbo, respectively. I'm rather pleased! :D


    I was smiling from the start after the first 4 rounds of 66 grain loads. 3 of the 4 are in one oblong hole :D 67 grains was so so. The 68 grain 4-shot group is actually almost identical to the 66 grain load as far as total group size is concerned (between 0.400" and 0.415" center to center) and then the 69 grain load which was almost identical to the 67 grainer.

    Since I would like the most velocity possible I'll be working with the 68 grain load. So I'll be back to the loading bench again working up some 67.5, 68, and 68.5 grain Retumbo loads. We'll see how much variance comes in with these 3 :)

    Thanks for following and I'll continue to keep ya posted!!
     

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  13. brentc

    brentc Well-Known Member

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    Try the 69-70 grain range. My setup is very similar to yours and I'm able to push the 180s up to 3060 fps. I have an accuracy node at 69.5 to 70 grains. Another load to try is 69.0 grains of H1000 with your choice of primer for 2950-3000 fps. If you look at the current Hodgdon data, both powders max at loads higher than I stated, but be careful and watch for pressure signs. The retumbo loads tighten up in ES close to max.
     
  14. brentc

    brentc Well-Known Member

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    This is about the same as my Pac nor #6 contour. Mine comes in right at 11 lbs with my Mark 4.