Increasing short barrel velocity

Discussion in 'Reloading' started by elkfirst, Sep 21, 2005.

  1. elkfirst

    elkfirst Well-Known Member

    Messages:
    62
    Joined:
    Feb 22, 2005
    My favourite deer gun is my Ruger M77 compact in 7mm-08. The barrel is only 16.5" long, swings fast and very accurate shooter, but my velocities are about 150 fps slower than a friend's 7-08 with a 22" barrel. Understandably so, but does anyone have an idea as to how to optimize the short barrel's velocity. I shoot Hornady 139 gr. behind 45 grains of IMR4350 powder, the bullets are seated 0.025" back of the lands. Would going to a faster powder such as Varget and decreasing my spacing to say 0.015" be a viable solution?
     
  2. jb1000br

    jb1000br Well-Known Member

    Messages:
    1,307
    Joined:
    Jul 8, 2003
    [ QUOTE ]
    My favourite deer gun is my Ruger M77 compact in 7mm-08. The barrel is only 16.5" long, swings fast and very accurate shooter, but my velocities are about 150 fps slower than a friend's 7-08 with a 22" barrel. Understandably so, but does anyone have an idea as to how to optimize the short barrel's velocity. I shoot Hornady 139 gr. behind 45 grains of IMR4350 powder, the bullets are seated 0.025" back of the lands. Would going to a faster powder such as Varget and decreasing my spacing to say 0.015" be a viable solution?

    [/ QUOTE ]

    go faster than varget.

    try benchmark

    JB
     

  3. Festus

    Festus Well-Known Member

    Messages:
    213
    Joined:
    Jul 18, 2005
    You didn't mention what velocities you and your buddy are getting. Obviously powder that is burning outside the barrel is not contributing to additional velocity and sometimes you can gain a bit by going with a faster powder. Take a look at www.reloadersnest.com - there are a couple of loads listed there for the 139 gr. bullet with the 16.5" barrel, one using RL-15 and the other Varget. You could try H4895 or IMR 4064 or you could even try H-322. I think your friend might have you by 100 fps or so but you might close the gap a bit.
    Good Luck, Festus
     
  4. elkfirst

    elkfirst Well-Known Member

    Messages:
    62
    Joined:
    Feb 22, 2005
    Festus, my 7-08 is averaging 2480 fps, my "friend's" is 2678 fps. That is actually 200 fps slower. Same powder and only 0.2 grain difference in load. Our barrel lenght differs by 5.5", this then accounts for a 36 fps velocity loss per inch of barrel. That is quite a bit, however the short barrel 7-08 will still be a very effective deer gun to 200 yds, maybe even 250. My "friend" by the way is in fact my daughter. This young lady out to 210 yards consistently puts rounds inside of a 4" circle with no resting aids other that her packsack. Just thought I'd throw that in, I'm pretty proud of her shooting abilities. Back to our topic, I'll work up a load with a powder that you guys were kind enough to recommend, I'll probably go with one of the faster ones. I'll give you feedback on how it all works out.
     
  5. LB

    LB Well-Known Member

    Messages:
    423
    Joined:
    Jul 22, 2004
    I have a 6mm with an 18" barrel, 4350 and 4831 works, but there is a muzzle flash indicating unburnt powder, at least inside the bore where it does some good.

    Is your daughter using the same powder? In any case, it is a solution to use a somewhat faster powder. Which one? Hard to say, you need to do a little bench work, maybe more than a little. To start, look at comparable pistol loads, in some manuals. Seems like there are a few silouette cartridges that are close to the 7/'08? That should give you some idea of what to try.

    Good luck, LB
     
  6. Festus

    Festus Well-Known Member

    Messages:
    213
    Joined:
    Jul 18, 2005
    Your daughter is an accomplished shooter. You have reason to be proud. /ubbthreads/images/graemlins/smile.gif Let us know how your testing progresses.
    Festus