WHY is my first shot high?

Discussion in 'Handloading and Reloading' started by docsleepy, Apr 7, 2013.

Thread Status:
Not open for further replies.
  1. BluegrassDan

    BluegrassDan Member

    Joined:
    Oct 25, 2008
    Messages:
    213
    Location:
    Elizabethton, TN USA
    How long do you wait between shots?
     
  2. ball3006

    ball3006 Member

    Joined:
    Dec 26, 2002
    Messages:
    2,874
    Location:
    Texas
    Because you don't flinch on your first shot.....chris3
     
  3. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    Hi guys, I did not clean the bore before this round.

    Metal temperature is a possibility, although the data that I've gotten so far doesn't seem to support it. Not much difference between days of widely varying temperatures

    I don't really think that I have any Flinch. The gun is fully in a benchrest. My other guns are Mosin-Nagant's. With either, I can hit clay pigeons at 200 yards reliably. What is odd to me is that the Mosin-Nagant, highly modified, does not have the cold barrel effect at all. Nor does my 6PPC.

    I usually wait one or two minutes between shots. These rounds are each hand loaded into the chamber.
     
  4. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    I have two scopes on order, whenever they arrive I will switch the scope.
     
  5. chaser_2332

    chaser_2332 Member

    Joined:
    Mar 22, 2009
    Messages:
    516
    Your overthinking the problem, if its repeatable whats the issue. Compensate an go on with it.
     
  6. c.latrans

    c.latrans Member

    Joined:
    Oct 19, 2007
    Messages:
    290
    Location:
    Big Sky Country
    Not that this helps your cause, but I am watching this thread like a hawk because I have a rifle that has done the same thing for 15 years. I love the gun so I have kept it and have tried every trick you have mentioned plus a few and NOTHING makes a difference. First shot of the day out of a cold/clean/fouled/dirty to the point of cruddy bbl.....every time that first shot is 4 inches straight high, then every time following shots drop right where desired and make pretty round groups. I have learned to cope with it, but it took me YEARS to trust the fact that I needed to adjust for the first shot. That is normally the one that counts, and it took a long time for me to be comfortable holding 12 inches low on a 300 yard shot. Its counter intuitive, but it works for me. Good luck, let us know if you figure it out!
     
  7. BCRider

    BCRider Member

    Joined:
    Nov 15, 2008
    Messages:
    7,844
    Location:
    Pacific North"Wet" Coast of Canada
    I worked with a fella that was on a SWAT team at one point in his police career. The scopes on their long distance precision guns were always set for that all important cold bore first shot. It was the followup shot where they relied on the mil dots or "Kentucky elevation" to adjust.
     
  8. DRYHUMOR

    DRYHUMOR Member

    Joined:
    Jul 6, 2008
    Messages:
    1,971
    I have some rifles that put cold bore shots where I aim, a couple that don't, depending on ammunition charge, bullet, clean barrel etc.

    As a primer ignites and fires the bullet it creates a harmonic through the steel of the barrel. The cold steel or clean cold steel will react differently than after the first shot.

    Like some had said, if your rifle puts the first round consistently high, but centered, you can either compensate for it or ignore it. Most of my first shots through a clean cold bore, I aim off target as to me it is a fouler. Unless in a hunting situation, in which case I compensate by holding where I expect the cold bore shot to go.
     
  9. benEzra

    benEzra Moderator Emeritus

    Joined:
    Dec 25, 2002
    Messages:
    9,467
    Location:
    Down East in NC
    If you have a chrono, you might try seeing if the velocity is consistent between the first shot and subsequent shots, too, just to rule that out as a factor.
     
  10. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    I might be able to Chrono it. What I need to know, is how many hours have to pass, before the shot will move back up. That would be important in an all day hunting trip.
     
  11. Eyesac

    Eyesac Member

    Joined:
    Sep 28, 2006
    Messages:
    1,393
    Location:
    Reno, NV
    Try pouring cold water on it to get it back to cold bore temps (something I've wanted to try for a while but haven't gotten around to). And if it works, let me know, cause you could get some cold bore work done in an hurry...
     
  12. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    New Scope Trial

    OK, here is the first, second and third shots after changing out scope to identical 4-16X scope. These are done at 50 yards (the farthest I dared attempting boresighted shots). Visually boresighted and let 'er rip.

    New scope with ring screws loctited.
    Front rest identical Rock BR.
    Used some of remaining batch of annealed, full length sized, handloaded rounds.
    Rear Rest identical
    Position held steady well within 1/4", firm hold as usual for this firearm.
    Barrel dirty, not cleaned since last shots, outside temp approx 80 F or hotter, done in shade as usual.
    Didn't think to chrono (sorry!)

    First shot is obviously high (remember this is 50 yards not 100 as previous).
    2nd and Third shots are right on each other.

    So I'm beginning to wonder if the threads on the barrel are shifting or something with the first shot. This is a stock standard Savage receiver, never blueprinted.
     

    Attached Files:

  13. Abel

    Abel Member

    Joined:
    Jan 30, 2010
    Messages:
    2,005
    Location:
    Eastern CONUS
    A candidate for rebarrel!
     
    Joe fonuki likes this.
  14. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    Yes, I think a shilen.

    Today ill try to chrono first and following shots. Wonder if the rifling has a bend or something else odd.
     
  15. Orkan

    Orkan Member

    Joined:
    May 21, 2010
    Messages:
    308
    Location:
    South Dakota
    It's unusual for a rifle that doesn't need a gunsmith's attention.
     
  16. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    Orkan -- did you have any suggestions?

    I've ordered a Shilen, Chrome-moly match, blued
    7m08 standard chamber (I neck down .308 cases so I'll have about .004" total clearance, which will be reasonable for a hunting rifle/target rifle)
    22" total length (selected to maximize stiffness, and the sporter was 22")
    S8 Bull Barrel (just like my 6PPC). 1.05 all the way
    9" twist (which will allow for heavier bullets or slower speeds)
    Standard Shank.

    The last Shilen I got went onto my 6PPC and although it is not a world-beater, it was absolutely reliable.

    I'll try to chrono today, dunno if it will work, because I have to get the FIRST SHOT.
     
  17. ford8nr

    ford8nr Member

    Joined:
    Jun 23, 2011
    Messages:
    1,990
    Location:
    Wisconsin
    You say the rifle is shot out of a rest front and rear. Does it do the same if you shoulder the gun and shoot it off a front bag? I'm thinking the rest might shift on the first shot then settle in for the test. Repeatability word be odd though.
     
  18. jerkface11

    jerkface11 Member

    Joined:
    Oct 27, 2005
    Messages:
    5,500
    Location:
    Arkansas
    Wait 5 minutes between shots. With the rifle kept upright with the bolt open.
     
  19. Float Pilot

    Float Pilot Member

    Joined:
    Jul 27, 2007
    Messages:
    3,154
    Location:
    Kachemak Bay Alaska
    My featherweight M-70 did that... Eventually I glass bedded the entire action and barrel channel. Now it does the first three shots into one hole and then they start to wander due to barrel heating.
     
  20. U.S.SFC_RET

    U.S.SFC_RET Member

    Joined:
    Dec 5, 2005
    Messages:
    1,897
    Location:
    The Old Dominion State
    Whenever I qualified with a Rifle in the Army the first round was always off. It's not unusual.
     
  21. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    fordnr -- It will be more difficult to spot if shouldered, as overall accuracy declines somewhat.

    As you can see from some of the groups, firing every 2 minutes gives touching shots....so barrel heating is a minimal effect.

    This rifle was bedded, and I rechecked it recently.
     
  22. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    Here's my data from today.
    Much hotter in Florida, 85 deg F. GNATS!!!!


    As you can see, once again the first shot of high, this case by 1 inch.
    The 3rd shot is the low one, I can't explain that.
    There are nine shots total and as you can see, the rifle groups pretty well when it is not the 1st shot. The 2nd shot is somewhere in that glob of holes.

    VELOCITIES: I dont' have the diffusers, so my chrony is very picky. It malfunctioned on most shots.

    1st shot was 2914 fps
    4th shot was 2902 fps (in the glob)
    8th shot was 2992 (in the glob)
    9th shot was 3023 (not sure where it went)

    So yes, the first shot is somewhat slower. If that held up, I might could have some rounds with 1 extra grain of powder?

    But the shilen barrel is on order now. 9" twist, bull barrel, 22" (short, thick), chrome-moly.

    Oh -- one commenter wondered if my rifle "settles" in the rear bag after the first shot. I would consider that a possibilty -- except I do NOT see this with my 6PPC in the exact same front/rear rest.
     

    Attached Files:

  23. Orkan

    Orkan Member

    Joined:
    May 21, 2010
    Messages:
    308
    Location:
    South Dakota
    Sorry for the abrupt answer. It was more to combat the idea that it's perfectly acceptable for the "cold bore" shot to be outside of the group. I don't believe it to be acceptable at all, and every rifle that I've owned which exhibited that behavior was rectified by handing it to a qualified gunsmith and working the problem together.

    The important thing to do is log this behavior, if you aren't already. Then subsequently log any action applied to rectify it. By this method you can close in on the problem through the process of elimination. It helps to have other highly qualified shooters at your disposal during this process in order to eliminate yourself as a variable.

    Personally, I would pop the barrel off and true up the action. If I'm removing the barrel and truing the action, then it also holds true that I'm putting a new barrel on. If those two things are happening, then it might warrant a new bedding job as well. Any rifle I've had which was exhibiting the symptoms you have documented here, was wearing a factory barrel. Upon rebarreling/truing/bedding... the problem no longer existed. As a result, it's very difficult for me to be able to point at a single root cause. I rarely expend any effort "forcing" a factory tube to shoot. If it doesn't shoot, it gets ripped off and I don't think for a second about it.

    I'm sorry if that's not much help, but you may find it to be a reality of your situation. I am thankful that you're documenting your experiences here though... because I believe that when you solve it, you will have effectively proven that no one should be forced to live with a cold bore shot that drops any differently than the rest. :)
     
  24. docsleepy

    docsleepy Member

    Joined:
    Mar 10, 2009
    Messages:
    1,023
    Orkan -- I suspect strongly that you're right.

    Since I'm not made of money, I go at things a little bit on a smaller scale. The only action that I've ever had trued, was a Savage action that shot well before it was trued, and did about the same after. That particular action got oodles better when a Shilen bull barrel went on it, and even a bit more when the trigger was changed out. It shoots the same first, last and middle.

    I have records on this gun since I put it together about a year ago. It got significantly smaller groups with I made one improvement a month or so back (that I haven't revealed yet in these writings). It had always seemed to have something "wrong" with the zero wandering or cold shot or something but I couldn't put my finger on it with so many other variables enlarging the groups. Learning how to do repeatable neck annealings removed a very obvious zero-drops-each-reload issue, and then my undisclosed improvement took the groups down to "touching" shots. This sporter 7mm08 barrel had never done that before. At was then that the cold-shot-error became blatantly obvious and since I couldn't figure it out, after several weeks I went to THR for advice. Thus the scope change, bedding check, etc etc. Still no fix. So now, will change the barrel. That I can do myself (as I did the 6PPC, and this 7mm08 as well) since it is a Savage.

    I also have a Mosin Nagant that I've been working on and now have it shooting groups <1" ("touching") at 100 yards. What got me going was that it has NO cold-bore difference, and I wondered why a 74 year-old gun was outperforming a modern hunting rifle....
     
  25. Orkan

    Orkan Member

    Joined:
    May 21, 2010
    Messages:
    308
    Location:
    South Dakota
    I don't understand. Why would you shoot a mosin at 100yds when the target is still well within bayonet range?
     
Thread Status:
Not open for further replies.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice