how can I get cold barrel shot to fall within group?

Discussion in 'Reloading' started by kweidner, Aug 10, 2008.

  1. kweidner

    kweidner Well-Known Member

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    I have noticed a trend in one of my barrels. The bbl is a .280 remington prohunter. This has perplexed me for quite some time. I have never experienced this phenomenon to this degree. The first shot out of either a clean cold or fouled cold barrel is a consistent 1.5 higher than the group. If I let the barrel cool for 15 minutes after the first shot to ambient temps., I can group with the 1.5" high shot all printing less than 1MOA. After the first shot, if I shoot a string, it will shoot a little less than 1 MOA 1.5 lower than the first cold shot. I have noticed it does not matter whether the barrel is clean or fouled. The results are the same with both. It is not a terrible issue as I have the cold shot zeroed 1" high at 100 and I hope not to take too many follow up shots. I do find it interesting, and was wondering if any of you have experience and maybe a solution for this. That particular load is a 140 grain sierra game king over 56.5 gr of reloader 22 seated 7 thousandths off the lands. It is probably important to note that It does the same with all loads I have tried even including factory ammo. Cold barrel=1.5 higher than group. What is up with this?
     
  2. J E Custom

    J E Custom Well-Known Member

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    Kweidner

    I have several rifles that do the same thing and this is how I deal
    with it.

    The first shot is considered a fouling shot because it removes any
    oil left from cleaning.(Even though you dry patch there is still some left).

    A lot of people clean and oil there rifle and shoot one shot for the zero
    (The second and third shots are normaly not used on game) so they
    are not as important as the first.

    I like to shoot a fouling shot and then just pull a bore snake through the
    barrel to remove the carbon then shoot for zero.

    After a session at the range I have my zero so I solvent clean the barrel,
    shoot a fowling shot (Making note of where it went just in case) pull the
    bore snake through the barrel and I'm ready to go hunting.

    If I do make a shot while hunting I pull a bore snake through and I'm ready
    to go again.

    So ether use your fouling shot to hunt with or clean in this way and shoot
    a dry,carbon free barrel

    J E CUSTOM
     
  3. kweidner

    kweidner Well-Known Member

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    J.E.,

    I'm with you. The only thing though is it seems to be a barrel temp issue. I have tried your method with this barrel as I too thought it was a fouling issue. The interesting thing about this is the cold barrel is the one that's high whether it's fouled or clean, if the bbl is ambient temperature, it is going high. I have multiple rifles that will do this on the fouling shot then settle in, however this one does it only when the barrel is ambient temp. I agree with you on the first shot zero. This one is the most important. Do you think the bbl. might be stressed?
     
  4. Mikecr

    Mikecr Well-Known Member

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    It sounds like you have it zero'd based on this CB POI.
    It sounds like your CB POI is consistant.
    This is normal with some barrels and is not a 'problem' at all.
     
  5. Bravo 4

    Bravo 4 Well-Known Member

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    It sounds like you have it figured out. You have identified your rifle shoots a cold bore round to a different point of impact from follow up shots. It kinda sucks when a rifle has this tendency, at least if you need a quick follow up but then that should make you want to make the first round count even more. Go into ever hunting situation thinking you only have one shot.
     
  6. kweidner

    kweidner Well-Known Member

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    I read a post this afternoon at another site dealing with this issue. The post suggests shooting a group over a 5 day period at the same target for group. 1 shot at target per trip. Although this sounds intriguing, it sounds like the author is almost doing an agg instead of a group because of the conditions from day to day. I hate this bbl. does this. Cold barrel will group if I wait at least 15 min per shot. I can also send a (warm up shot ) and then proceed to the group. It makes me wonder what are the characteristics that make a rifle do this.....Is it the bbl stress, maybe tooling marks in the bbl? I am perfectly satisfied with the cold shot. I rarely have to make a follow up shot. However, when I do, I doubt I will have the luxury of a 15 minute cooling period. Granted for true distance shooting I will be using my cooper 6.5X.284. My cooper doesn't care hot, cold, dirty, clean, 30 degrees or 100 degrees, it puts them under .3 MOA if I do my part. This .280 is a great walking gun as well as easy to take through the dense cover areas I encounter here. My cooper, I have a tendency to baby. Has anybody experimented with the technique described above?
     
  7. boomtube

    boomtube Well-Known Member

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    If any part of the barrel, especially the chamber section, is tightly fitted or glassed, remove that contact.

    Most barrels are, at least in the first few inches, somewhat cone shaped. When the chamber heats and expands it pushs out and stretches forward. Both actions place an upward force on the barrel and it dorsn't take much to move the line of bore 1 1/2".
     
  8. Mikecr

    Mikecr Well-Known Member

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    I do cold barrel load development with each hunting barrel. Even lower stress cut rifled barrels.
    It can take months. It is completely different than BR group shooting.
    But you've implied that this is a hunting gun, and so your focus SHOULD be on cold barrel ACCURACY
    (not grouping).

    It was suggested that you might accept a low potential for followup shooting. I suggest you make it a rule..
    Say this:
    IF I MISS, IT LIVES ANOTHER DAY.
    There, it's simple, sporting, and will help you accept your true capability.

    Don't hate a hunting barrel until you truly define it's accuracy potential. I mean for all you know, it could be fantastic.
    I had a Browning Eclipse in 223 with BOSS. It would never group consistantly under 1/2moa. But I managed to get it to a point where I could pick it from a case, and place a single shot within 1/4moa of my mark. I could do it five times, on five different days, as mentioned.
    Best woodchuck gun I ever had.
    Nothing I have today is this accurate, even though all GROUP better than 1/2moa. It's funny you mention Cooper, as my best accuracy right now comes from one, again in 223. And again, the cheapest gun in my safe!

    A couple tips here;
    -One thing that helps for cold CLEAN barrel shots is Tungsten coating the bullets, and a pre-burnishing the bore after cleaning.
    -One thing that screws up cold barrel accuracy, is oil in the bore. Even a trace is bad until burned completely out. So always wash solvents out with the best alcohol you can buy.
    Either way, that bore needs to be dry for consistant cold barrel shooting.
     
  9. mattj

    mattj Well-Known Member

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    Some folks think that the "cold bore" changed point of impact has nothing to do with the rifle and everything to do with the shooter... might give the above link a read for some ideas. YMMV.

    PS: That whole thread has really good discussion on different potential factors, etc. Good read.
     
    Last edited: Aug 10, 2008