Testing out the new toy last night.  1 in 7 twist barrel, 14.5".  KAC 300m BUIS.  Shooting a bit high at 50 yards (using an 8x11 sheet of paper, I was about 3" high at this range).  Pretty much dead on at 25 yards.  Using the SA surplus ammo - I believe it is 55 grain.  I know, light for this twist, but good for plinking.

Move over to the 100 yard range.  Using a paper target approximately 1 foot by 2 foot, I'm not even hitting the paper.  Aim low, aim high, nothing.  

Move up to 25 yards and again I'm dead on.

So, I figure I'm looking at one (or more) of three possibilities:

1.  I suck.

2.  My sites are way off.

3.  (This is why I posted this in the ammo forum-) My 1 in 7 twist barrel is not stabalizing the 55 grain bullet to the point that, at 100 yards, it is waaay outa the target path or is spinning the bullet apart before impact.

I should note that at 50 yards I believe I could detect tumble in the bullet; i.e., the hole in the paper was elongated rather than a clean circle.

Any ideas?

I plan on using BH 77 grain SMK once the funds come around.

Since I can not see you while you are shooting it is hard for me to offer much advice about option 1.  I assume that you are shooting fom a rest?

If you are hitting dead on a 25 yards you should still be hitting 2' x 2' targets at 100yards.  I suggest a larger target so you can see where those rounds are going.

I have shoot XM193, Q3131, Q3131A, SAM193, and Guatamalean  all of which shoot 55gr bullets.  All of the above stated rounds worked perfect in 1/7" twist barrels that were 20" and 14.5".  Now this does not eliminate the possibility that your barrel is defective in some way.

The Azalin

Shooting from a rest at 50 and 100 yards.  I was alone, which kinda' sucked because its nice to have a spotter who can tell you where the bullet may be hitting.



Now this is not a pleasant thought.  Seems to me that if it's working consistently at 25 and 50 yards that it should be ok - ?

1) Zeroing at 25 yards will cause the rounds to be high at 100 yards (and still rising).  Rezero at 50 yards.  For more details and info see the Zeroing Methods section at MD-AR15.com to see charts explaining why zeroing at 25 yards is a bad idea.

2) if you are keyholing at 50 yards then YES you have a serious issue with your barrel.  A 1:7 twist barrel should not be keholing with 55gr ammo.  I'd see about replacing the barrel.