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Thread: Cold bore first shot. rifle/barrel or powder load caused?

  1. #1

    Cold bore first shot. rifle/barrel or powder load caused?

    Is the slightly out-of-subsequent-group cold bore first shot a function of the rifle and barrel or purely the load?

    Will there be one load/bullet combination for every barrel that will go to the same point whether the first or the fiftieth shot of a session? Or is it just a vain search?

    Most of the loads and factory rounds that I have found to group well in a range session...warm barrel...shoot 20mm-ish high from a cold barrel. Is this because that is what all rifles do, or because I have still not got the load right?

    Alan

  2. #2
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    When my brother did this sort of thing, being trained to shoot people, with a 'scoped rifle, as a job he zeroed twice.

    As below. He'd fire one shot, cold barrel, on one target and a second shot, warm barrel, on a second target. Allow to cool to stone cold. Repeat. Do this another three times and set zero as the mid-point of the two groups.

    So it's a function of the warm barrel and, usually, that said barrel is a standard lightweight or medium weight hunting rifle barrel rather than a bull barrel. How far out of the subsequent shot group is that cold barrel shot?

    In theory a stiff "bull" barrel should not string its groups as much as the heat being absorbed by more mass of metal has, initially, less immediate effect. For when a barrel gets hot it bends.

    It's a vain search if, if, you fire shots in quick succession. If you fire them one shot, wait five minutes, one shot and so on they they'll all group together.
    Last edited by enfieldspares; 09-05-2016 at 14:36.

  3. #3
    Quote Originally Posted by Alantoo View Post
    Is the slightly out-of-subsequent-group cold bore first shot a function of the rifle and barrel or purely the load?

    Will there be one load/bullet combination for every barrel that will go to the same point whether the first or the fiftieth shot of a session? Or is it just a vain search?

    Most of the loads and factory rounds that I have found to group well in a range session...warm barrel...shoot 20mm-ish high from a cold barrel. Is this because that is what all rifles do, or because I have still not got the load right?

    Alan
    what rifle, barrel and load?

    is this a recently cleaned barrel?

    not had this phenomenon in any of my own rifles or if I have I have either not noticed it die to the insignificant nature of the differing or haven't shot well enough to indicate that it was the rifle!

  4. #4
    In the past I always put it down to the jerk behind the trigger...and it is still more than likely just my erratic shooting...maybe I just do not get into position properly for the first shot.

    Most of my shooting and load development at targets has been from quad sticks rather than a bench and the elevation is the most variable with those.

    But the cold barrel shot has often been different from the subsequent ones...

    Since joining a tunnel range which removes the wind variable, some of my groups are getting a bit better, either through bench support, practice or better loads, but still the first cold barrel difference seems to be present.

    I know in the grand scheme of things 20mm is not a lot and the eccentric position seems to be consistent per load / round.

    Barrel cleaning seems to exacerbate it, but even with just a couple of bore snake pull throughs after each session it seems to pertain.

    Blaser R8 22" standard weight hunter barrel .308W.

    Just intrigued because I have read others refer to it, and was not sure if it was a rifle-and-barrel linked phenomena or just a load-linked thing.

    Alan

  5. #5
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    It's quite normal with that type of contour weight barrel. Fire ten shots and, with some rifles, it'll start to string after shot six or seven and the shots will climb high and usually to the right. It's an odd thing to watch as they go 1/2" to 3/4" up at each shot. Like a dot-to-dot puzzle.

    Sporting rifles that are made from military rifles...such as those based on the Mauser 98...or the Lee-Enfield if the replacement barrel is of similar contour exhibit the trait less. They are after all designed to be a able to provide rapid fire without loss of accuracy. A benefit of that old Parker Hale or BRNO. They don't do the "hot" "cold" thing and usually won't string for five shots at least.
    Last edited by enfieldspares; 09-05-2016 at 20:44.

  6. #6
    In our situation as hunters, I think that the point is moot. Just zero for a cold barrel as this is what you need to be your most accurate shot.
    Quid enim proderit Homini si lucretur Mundum totum et detrimentum faciat Animae suae?

  7. #7
    One US SWAT sniper team's policy was to finish a range session, clean the rifle, then put 3 (I think) rounds through it and then store the rifle. They found this maintained consistancy for the first shot, which for them was all that mattered.

  8. #8
    I'd love to know the answer to this one, ask 2 shooters & you'll get 3 different answers! My .243" Sako 85 Varmint regime is after 'brush cleaning' put 2 rounds through the barrel & lightly clean out powder residue for next 20 rds or until POI changes significantly & start again. Completely different for Sako TRG only light cleaning for 100 rds or so. One of life's mysteries to me.
    Last edited by Nick T; 10-05-2016 at 07:08. Reason: more info

  9. #9
    Quote Originally Posted by Alantoo View Post
    Barrel cleaning seems to exacerbate it, but even with just a couple of bore snake pull throughs after each session it seems to pertain.
    I don't clean a barrel unless it has seen a string of shots at a range or load development or has suffered in poor weather.
    i will give it a proper clean after its seen a number of shots on independent outings, not fixed but 20 seems about right
    other than maybe a dry patch and a lightly oiled patch to clean out condensation or debris

    I would say if a pull through or dry patch is affecting POI then there is more to it than heating the barrel up.
    If I clean my tikka 300wm it takes a LOT of rounds to get back on track. likely poor bore condition but I couldn't care less, precision and accuracy are the ONLY things that matter, clean barrels that shoot like crap are useless
    I have shot my 300wm until I could cook bacon on the moderator and it doesn't walk

    surprised that a Blaser will show that even with a light profile barrel
    not fluted is it?
    wonder if it might benefit from some stress relieving?

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