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Author Topic: Ruger Gunsite Scout/Hunting Rifle Project.  (Read 6755 times)

cpaspr

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Re: Ruger Gunsite Scout/Hunting Rifle Project.
« Reply #25 on: August 07, 2016, 05:04:48 pm »
I have some rifle newb questions. The 168 federal match rounds seemed to impact higher than the 150 grain rounds. Does this mean that the bullet's arc is more pronounced on the heavier rounds?

Assuming these are all factory rounds in your picture, your vertical point of impact will vary for up to three/four reasons (all at the same time):
1) different bullet shape/configuration with the same weight of bullets will have a different ballistic coefficient, thereby changing the wind drag factor.
2) different weight bullets of varying ballistic coefficients will fly differently due to simple physics.  Think about you throwing a tennis ball vs softball as hard as you can.  Same amount of muscle behind each throw, ball held the same, thrown the same. 
3) amount of pressure behind the bullet, and the speed of that pressure wave.  I.e. different powders will launch the same bullet differently.  Add in different bullets with different ballistic coefficients, and voila! further change of POI.  Using the tennis ball vs softball analogy, you throw one and your 12 year old kid brother throws the other.
4) and this one is mostly only for handloaders and is an example of Mattitude's explanation in action: changing the amount of powder behind the bullet, all other factors being the same, means the bullet has more or less time in the barrel.  Recoil starts at the instant of ignition.  Example:  I had a 262gr bullet I was shooting from a .45 Colt that shot low with the rear sight as high as it would go.  I dropped the powder charge 2gr and it started shooting to point of aim.  The bullet was in the barrel just enough longer that the rise in the recoil pulse put the round right where I was aiming.
 
And these are all in addition to and/or explanation of your bullet arc hypothesis.

_________________

Bottom line, find a proper bullet (weight/construction) for the game you will be hunting, and then find a factory round that your gun likes for that load. Don't bother with the match type bullets if you're going to be hunting.  Those are for punching paper, and won't shoot the same as hunting ammo.

As an example, for 100 yard shots, my .30-06 really likes 165gr Remington Cor-Lokt bullets ahead of 57.0 grains of IMR 4350, with the bullets loaded out long.  I can cover a three shot group with a nickel.   For 150gr bullets I worked up a load where I can cover three shots with a quarter.  180gr bullets?  Best I could get was 2" groups.  Those are all hand loads, but the principle is the same.  Find what the gun likes, and practice, practice, practice.
Oregon

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