Mk4 gp velocities

Discussion in 'General Airgun Chat' started by bigboab, Dec 20, 2010.

  1. bigboab

    bigboab New Member

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    Hi there,

    don't know if anyone can help - my gp only goes up to 785 fps (although it shows rite up to 999 on the info screen) I'm happy with the 785 for using 8.4gr pellets but when I was trying some various 7.9's it still won't let me up the fps to 815-820! Which means I'm only getting just over 10ftlbs! I no this is obviously a safety feature to stop heavy pellets a high velocities, but is there anything I can do to up it slightly for using the lighter pellet or is it just a case of having to stick to 8.4's if I want 11.5ftlbs???

    Any info would be gretly appreciated

    Regards Robert
     
  2. Scooby

    Scooby Pete Dutton

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    815-820 with 7.9gn pellets is 11.65-11.8
     
  3. bigboab

    bigboab New Member

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    Yes that is what I would like to get from using 7.9's but due the rifle being factory set with a maximum velocity of 785fps which is perfect for 8.4's but I would still like it a bit faster for the lighter pellet so I don't sacrifice any power?

    I thought 820 was the maximum allowed for ft, I appologise if that's to high, even if I could get it to 810, but 785 is just so low for the light pellet
     
    Last edited: Dec 20, 2010
  4. Ratinator

    Ratinator Well-Known Member

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    bfta comps

    bfta say your rifle should be 5 fps slower than legal limit.
    will be setting up my mk4 soon with 8.44,would be interested to here of your findings with the lighter pellets.
    atb simon
     
  5. Scooby

    Scooby Pete Dutton

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    Sorry misread your post, thought you were getting 815-820 already, if you are only getting 785fps with the 7.9gr pellets then give Daystate a ring and see if they can help
     
  6. raisedbybrocks

    raisedbybrocks New Member

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    I shoot mozzies at 780fps by choice. There is naff all difference in windage, infact I find them more predictable at this speed. Maybe less deflection.:)
     
  7. bigboab

    bigboab New Member

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    Thanks for the advise guys, I'll give daystate a call and see if there is anyway around this, if not I'll try the 7.9's against the 8.4's at 785fps and I'll post how I get on!!

    Thanks Boab
     
  8. Dave Ramshead

    Dave Ramshead England HFT Team squatter

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    It's running up against the power cap, if it was mapped enough to give 820fps with 7.9's you would be capable of going over 12fpe with 8.4's or heavier.
     
  9. bigboab

    bigboab New Member

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    Yip I understand that which is a bummer, but then if looking at it that way any irresponsible shooter could go and put 10.9gr bisley magnums or the likes through it at 785 which would still make the gun illegal at the capped velocity. So if that is the case its already is down to the shooter to make sure it is legal anyway?? I think a 10.9gr pellet at 785 capped level would still have more muzzel energy than an 8.4gr pellet at 815fps?? I don't want anything illegal I just like the flatter trajectory of the lighter pellet and would like to get the most out of the rifle with that weight of pellet.
     

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