7mm RUM/180gr Berger Disappointment

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Hicks, Sep 15, 2008.

  1. Hicks

    Hicks Well-Known Member

    Sep 19, 2007

    Spent the money for the 180gr Bergers a couple of weeks ago and have been working up a load. I'd really like to take advantage of the high bc of these bullets, and I've never heard a dissenting opinion of Berger bullets in general. Upon the advice of Carlock and others I tried Retumbo and US869. I laddered both of those powders and found that US 869 gave significantly higher velocities than Retumbo, up to almost 3200fps before the cases showed signs of pressure. The ladders showed some sweet spots, but because of the higher velocities I got with the 869 I decided to try loading some test rounds with that powder. I loaded 5 rounds each at 99, 101, 102grs respectively. Groups started out at almost 2" and went up from there. I only fired three rounds at the 102gr level before I gave up. To say I'm very disappointed in the Bergers would be an understatement. I thought I had everything set correctly, including seating them almost two thousands into the lands. I know it's not me as I can hold 3 160gr Accubonds inside 1/3" at 100 yards with that rifle. What did I do wrong? The only thing I can think is that the twist rate is not fast enough in this bbl to stabilize that heavy of a bullet. Has anybody had any luck with these bullets in a factory 26" bbl? How about the 168gr Bergers or Sierras? Any advice would be much appreciated.

  2. gamedog

    gamedog Well-Known Member

    Aug 16, 2007
    I'd try a few just touching the lands and see how that does.

  3. Marine sniper

    Marine sniper Well-Known Member

    Sep 11, 2005
    My 300 WBY likes them (210's) .010 off the lands..averages 1.5 in at 300 yards.
  4. geargrinder

    geargrinder Well-Known Member

    Nov 6, 2006
    You didn't say what rifle or barrel you are shooting, but my first inclination would be that you don't have fast enough twist.

    Berger reccommends a 1 in 9" twist. Most factory barrels are 9.25" and slower.
  5. Tikka Lover

    Tikka Lover <strong>Official LRH SPONSOR</strong>

    Feb 2, 2008
    My 26" barrelled 300 Win. Mag. Likes them about .020 off the lands and you might want to come down a bit with the powder charge. My best groups are 3 grains below max. Max isn't always the most accurate load.
  6. royinidaho

    royinidaho Writers Guild

    Jan 20, 2004

    I hate to rain on your parade but......try going with the lower velocities and see what happens.......

    Also, if the group size opens the farther you jump them into the rifling, excessive velocity is definitely indicated.

    I tried 150 Bergers in a 270 AM and was sorely disappointed. The problem was explained to me very well by one who knows.

    His words described something like wringing out a very wet towel. That's what the bullet looked like as one end entered the rifling and the other didn't. All groups were very bad and some bullets didn't make it to the backstop.

    They work wonderfully in a 270 Win @ 3000 or so and a 10 twist. Between the tight twist of a Lilja 3 groove bore and velocities in the 3500+ range the jackets just wouldn't take it.

    I'd really like to try some of Berger's "thick" choices and see what happens.
  7. remingtonman_25_06

    remingtonman_25_06 Well-Known Member

    Jun 4, 2003
    I doubt its a stability issue. True that most 7mm's are 1 in 9.25" and Berger does recomend a 1 in 9"

    However, my 7 RM is a rem 700 w/factory tube and a 1 in 9.25" and it shot the 180g VLD at 1/2 MOA and 2825fps, bullets were seated right at the lands. I am only 700 ft ASL so if there stabilizing out of my 7 RM at near 400fps slower, it just wouldn't make sense that its a stability/twist issue...

    Try that Retumbo and seat them at the lands or in a bit and report back.

    Some guns just dont like a particular powder/bullet combo, but will love another powder with the same bullet.
  8. eddybo

    eddybo Well-Known Member

    Jan 5, 2007
    I have had great luck with the 180s out of a 7wsm and plan on trying them in a new RUM I just got. I agree that not every barrel likes every bullet and that may be the case, but I would play with the seating depth a bit before I gave up on them.
  9. tillroot1

    tillroot1 Well-Known Member

    Apr 27, 2005
    I would agree with Roy, I would take the velocity down to around 3000 to 3050 fps and try seating depths from that. you may be surprized. good luck! Ron Tilley
  10. Hicks

    Hicks Well-Known Member

    Sep 19, 2007
    Ok, all good advice. I'm hopeful again that I can get these to shoot well.

    Question: How do you guys go about working up a load? Do you ladder or do you load 3 at various powder weights or seating depths? I'm not sure how to proceed and I'd like to not waste powder or bullets if I can at all help it.

    Any advice would be appreciated,

  11. badaboom

    badaboom Well-Known Member

    Apr 30, 2007
    My recent loads for test were same powder
    different depths
    10 with 75 grains powder initial Seating depth .005 off max
    5 with 75 grains powder a little more tight on the Seating depth .003

    10 with 76 grains powder initial Seating depth .005 off max
    5 with 76 grains powder a little more tight on the Seating depth .003

    5 with 77 grains powder back with initial Seating depth .005 off max

    Using 300 WM 200 Sierra GK SPBT bullets with IMR 7828SCC

    This is my most recent test batch for the 300WM
    batches of 6 are my standard usually.
    I just decided to due a bit more this time.
    Big thing is noting the measurements and how each shoots out of the firearm.

    It can't hurt to test more to insure the possiblities

    Best of luck
  12. davewilson

    davewilson Well-Known Member

    Feb 19, 2004
    i've loaded for this combo but with a different powder(872) and a 30" 7 twist barrel. i shot them at 3250 and the jacket was strong enough to take a 7 twist with 3 grooves.

    this reminds me of a gun a local smith built to compete at 1k back in the 70's. a 30+ pound monster, full bench, finally ready, back to the range and you could have bought that gun for $5 when it didn't even shoot an inch at 100 yards. everyone was talking about what they were gonna do with this POS. i asked if i could shoot a group with it and of course they said go ahead shoot em all up, didn't matter any more. i took a target out to 200 yards and got quite a bit of laughter from the gang. lined it up and just started pulling the trigger. easiest gun i ever shot, it just layed there like some of my old girlfriends. after i shot 3 i was sweating because i could see the group was almost a hole in the paper and i had never done this before. when i put the last 2 in the same place, i was pretty happy but no one even came over to look at the spotting scope. they asked if all the holes were on the paper. when the smith looked and told them the group was less than a 1/2 inch they laughed at him. he came in 3rd place for the year with that gun.

    the point to all of this is bullets aren't always stabile at 100 yards. sometimes you have to shoot at farther distances to see how accurate it really is.
  13. Hicks

    Hicks Well-Known Member

    Sep 19, 2007
    Ok, so I need to back off on the 869 a bit, back off on the seating depth a bit, and maybe shoot at 200 yards to see. I'll be working on that this afternoon.

    Another question: When working up a load, how often do you guys clean the copper out of the bbl? Or do you at all?

  14. Slopeshunter

    Slopeshunter Well-Known Member

    Apr 27, 2006
    Good line.:D