POI Drift 300grain Matchkings 338LM?

Discussion in 'The Basics, Starting Out' started by Perkules, Oct 17, 2003.

  1. Perkules

    Perkules Well-Known Member

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    Made my first 300 MK loads yesterday, got some nice groups but also some flyers every now and then. I thought it was bad shooting because it was getting dark but today the thing was still there,in a good light. I used only one load today.

    I have a stock Sako TRG-S. Shot a bunch of 250 Scenar moly factory rounds with less than half an inch groups and never noticed this drift. So:

    With the MK:s the first shot from a cold barrel is there. Right where it´s supposed to be,yesterday and today. Vertically the same as Scenars. The temp is arond 30F now so I let the barrel cool down for only five minutes between the shots.

    What happened was that the POI drifted to the left again, just like last night but now it actually stayed there,I got the best groups at more than an inch to the left. This is only 100 yds shooting here, testing.

    After a few rounds it started to drift back to center, got 1/2" groups again but closer to the "starting" POI,verticalwise. ???????

    Is this just bad shooting or what? Any experience appreciated,I used a decent bench, maybe the rear support could be better. I also had the bipod attached but folded to "carry" position for some real world weight.

    Here you can see what is going on. The first one is there,then the 1/2+ inch group is somewhere else. After some groups it moves back towards the center and yesterday I got two 3/8" groups as well -but in a wrong place. I have shot only moly 250 factory Scenars before and this is something new.

    [​IMG]

    The load was only 2595fps because of the 26" barrel but it is fine for my hunting purposes. 85 grains of VV N165,standard COL, CCI 250 Magnum primers. SD for ten rounds was 16.

    Any ideas? I´d be quite happy with this for 500 yds moose with 1/2" grouping but the drift is no good. The scope is fine,Scenars shoot where they are supposed to. Plus,the twist is 10", not 12". Is it just the heat? If so,why does it drift back? [​IMG]
     
  2. jb1000br

    jb1000br Well-Known Member

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    I dont know if it could be causing it, but i would scrub the hell out of the moly that you laid down and shoot some naked rounds and scrub the hell out of it again. The residual moly needs to be shot out before you try to find a load for a naked bullet. Things will be inconsistant with the moly left in there.

    if that is not the problem you could try a cryo treatment to relieve stresses in the barrel maybe??

    JB--o yea, i hope you dont mind i borrowed your signature.

    [ 10-17-2003: Message edited by: jb1000br ]
     

  3. Perkules

    Perkules Well-Known Member

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    Yhanks for the reply JB,

    moly... sheesh,I´ve heard about this. Just another thing to learn by trial and error. I did some careful "breaking in" with the moly stuff,later I heard that it may not be the best idea. That was all I was able to get, moly Scenars.

    Dang,can I just shoot the moly out or does it need mucho manual scrubbing? Or... what if I molycoat the Matchkings? [​IMG]

    Kinda makes sense now. Anyway,I will see the 300 grain MK story till the end, moly is a minor nuisance here,I will get rid of it one way or another.
     
  4. Len Backus

    Len Backus Administrator Staff Member

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    The TRGS has a very inadequate recoil lug, especially for such a robust cartridge. Could be shifting the point of impact.
     
  5. Perkules

    Perkules Well-Known Member

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    Thanks Len. Maybe it needs to be worked on, gotta call Sako folks and see about that. It should be a warranty job in this case.

    Still wondering why this does not happen with Scenars...??? And why the first round is always right in the spot?

    Well, moose time, 45-70 dog guide fun. More comments welcome.
     
  6. Perkules

    Perkules Well-Known Member

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    It´s the recoil lug / bedding thing. [​IMG]

    Something "gives" a little, this sideways drift is a known problem,I talked to some people who had heard about that too.

    What should I do now? Take half an hour breaks between the shots? A bedding job? I can live with the stock otherwise.

    Ideas,please? Re- stocking is not an option now although it would fix the problem. I´ll see if I can fix it with the existing stock.
     
  7. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Check the stock for fit and make sure the barrel channel is not touching the barrel at all.

    Recoil lug would be suspect to.

    Later
    DC
     
  8. Len Backus

    Len Backus Administrator Staff Member

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    The fix that MPI Stocks did on my TRG-S was to add an after-market recoil lug just where the barrel meets the action. The stock is inletted to allow the new lug to fit snugly down into the stock.

    Not a big job but the barrel threads have to be adjusted so headspace is correct.
     
  9. Perkules

    Perkules Well-Known Member

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    Thank you very much,Len!

    That makes sense. Everything looks fine otherwise, the lug must be it. But heck, if this is how Sako / Benelli /Beretta whoever do things these days ... very bad for them.

    Officially ,the problem has been fixed. In practise,nope. Grr... [​IMG]

    [ 11-12-2003: Message edited by: Petander ]
     
  10. Mark_in_utah

    Mark_in_utah Well-Known Member

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    I had a rifle that was grouping poorly. Pillar bedded and floated barrel. The lug had been bedded with the customary tape on the front of the lug to aid in the easy removal of the action from the stock. This also allowed the action to move front to back if the action screws were loose. He suggested that I re-bed the recoil lug with ZERO clearance. Now the action must be gently pried out of the stock, but the pattern has tightened up.

    Mark in Utah
     
  11. James D.

    James D. Well-Known Member

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    The newer Tikka has a bedding similar to the Sako series.
     
  12. Perkules

    Perkules Well-Known Member

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    Man,busy tracking hit-by-car moose etc... anyway, next tuesday I will know more, the Sako factory rifle service guy (notice: only one!!!) will be back at work then.

    Meanwhile I keep on hunting. Because the first round -clean barrel or not- is where it´s supposed to be I´m doing fine with the deer. Hope they come tonight.

    Time to go again, one shot,one kill. [​IMG]
     
  13. Dave King

    Dave King Well-Known Member

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    Petander

    Sorry, I haven't gotten the other box of MK's shipped yet... just finished a week long inspection. I'll box those critters up first part of next week and airmail them.

    Good luck with the moose and deer.
     
  14. Perkules

    Perkules Well-Known Member

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    Dave,no problem at all!

    I won´t waste them for any testing now, the load is nice and I got it done quite fast. [​IMG]

    And... my package for you is still here as well, sorry. Maybe I´ll get it in the mail on Tuesday. Lost the car accident moose by the way,it is not badly hurt. The car got wrecked,moose fine... [​IMG] Then we had a hunting dog competition in our area on Saturday... lot´s of things going on!

    The deer are hiding really well now. But they will come one day,they have to. [​IMG]