Double Tap Ammo

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jhlobik, Oct 13, 2009.

  1. jhlobik

    jhlobik Member

    Messages:
    23
    Joined:
    Jun 30, 2009
    I've had a funny experience with this DT Ammo that is so highly advertized.
    I was shooting 300 win mag with millet mil-dot scope at 1/4" per click @ 100.
    Normally, I have it zeroed for 150gr SST Hornady ammo at 200 yards.
    Yesterday, I've tried several brands with bullets from 150-180. They all ranged close to each other. Exactly where they were supposed to be according to ballistic charts. With 150gr SST ammo zeroed at 200 yards, 180gr SST bullets were just a bit lower, about 1-2 inches on the average. Totally normal. Made number of shot for consistency and all was cosistent.
    Now, without changing the scope setting, I've tried a 200gr accubond double tap ammo. First shot went 8 inches low at 200. Tried again, another one 8 inches low right next to the first one. To make the long story short, I had to come up 16 clicks for that ammo to get it to zero in at 200 yards. There is no way it should hit that low compared to 150-180 grainers. Either they are lying about its advertised velocity, which should be 2900 fps by the way for that 200gr accubond, or I'm missing something here. Must say that once I've made final adjustments, the accurace was good. Anyone had any experience with that ammo ? Comments ?
     
  2. J E Custom

    J E Custom Well-Known Member

    Messages:
    7,313
    Joined:
    Jul 29, 2004
    Being lower does not make automatically slower !

    Some times when you change bullet weights you change barrel harmonics.

    I have seen heaver, slower bullets go higher than lighter bullet loads.

    The easy way to check velocity is with a chronograph. most factory velocities are overrated
    and overstated.

    J E CUSTOM
     

  3. steve smith

    steve smith Well-Known Member

    Messages:
    244
    Joined:
    Jul 4, 2001
    What J E Custom said. It's not an actual change in the trajectory, but a change in the point of impact caused by a different projectile. This can be a bit easier to see when you have several different bullets loaded to different velocities. Shooting these loads at 100yds you might end up with a different point of impact for each load, but that has nothing to do with the long range trajectory. It simply means that for each load you will have a different reference point to which you start measuring the drop.
     
  4. jhlobik

    jhlobik Member

    Messages:
    23
    Joined:
    Jun 30, 2009
    Well, i understand that reference point is different for each type of ammo.
    Its just 6 different factory loads I've tried all grouped close together at 200 yards. Some 150gr and some 180gr. And this 200gr accubond by dobule tap, which has a ballisic coefficient of about 0.588, went 8 inches lower at the same scope setting. I expected it to go a bit lower, but not by that much. Well, at least I know now that it takes me exactly 16 clicks up on my scope to switch to this ammo, from my usual setting. Can't wait to try it at 300 and 400 yards.
     
  5. jmden

    jmden Well-Known Member

    Messages:
    2,725
    Joined:
    Nov 2, 2003
    Run it over a chrono. I bought 100 rds of .40 S&W DT ammo with the 200g Hornady XTP rated at 1050fps with a 4" barrel. My barrel is 4 1/4" and is shot on average nearly 100 fps slower than advertised.