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  #51  
Old 07-01-2016, 11:01 AM
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Quote:
Originally Posted by Riverpigusmc View Post
Try this. ..fire a 3 shot group. If low, aim at the exact same point you aimed when firing, then, holding your rifle steady, adjust the crosshairs down to meet the center of the group. That should zero it at that range. If the next group is low, the scope is suspect imho
Bingo, easy peasy....
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  #52  
Old 07-01-2016, 11:04 AM
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Quote:
Originally Posted by Riverpigusmc View Post
Try this. ..fire a 3 shot group. If low, aim at the exact same point you aimed when firing, then, holding your rifle steady, adjust the crosshairs down to meet the center of the group. That should zero it at that range. If the next group is low, the scope is suspect imho
Fair enough!

Thanks!
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  #53  
Old 07-01-2016, 03:58 PM
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The charging handle is very easy to replace, and might as well be removed for cleaning/lube any time the BCG is removed for cleaning/lube. Simply place some downward pressure (with the upper upright) on the handle as it's pulled to the rear. The handle should readily slip through the dismount notch.

I wasn't sure what was meant by your "slightly low, no matter what adjustments" statement. I presumed you were surprised at how the POI is with it zeroed at 100 yards.


FYI, the SS109 bullet has a ballistic coefficient very close to the 69 grain SMK, so that's what I used in Sierra Infinity. At 2900 fps with the scope (in P.E.P.R mount) zeroed at 25 yards, the impact is 1.3" high at 50, 3" high at 100, 3.5" high at 150, 2.6" high at 200, zeroed again at 250 yards, and 4.4" low at 300 yards. This allows for hits within + or - 4.5" from POA from the muzzle out to 300 yards.

With a couple exceptions, I run either irons or Aimpoints on all semi-auto rifles....especially carbines. Magnified scopes are only used when developing handloads for them.
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  #54  
Old 07-01-2016, 04:29 PM
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Originally Posted by Grizzman View Post
The charging handle is very easy to replace, and might as well be removed for cleaning/lube any time the BCG is removed for cleaning/lube. Simply place some downward pressure (with the upper upright) on the handle as it's pulled to the rear. The handle should readily slip through the dismount notch.
Excellent! Thanks! I'll check that out.

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Originally Posted by Grizzman View Post
I wasn't sure what was meant by your "slightly low, no matter what adjustments" statement. I presumed you were surprised at how the POI is with it zeroed at 100 yards.
They were placing 1-2 rings below the bullseye center dot on a standard AP-1 tombstone target at 100 yds. But, due to my total "noviceness" about sighting in, I'm not ready to declare it's a malfunction of the scope. It's more likely something I'm doing wrong... be it not keeping the rifle level/steady when adjusting, or ensure the scope is mounted properly, or anchoring the front bag directly on the barrel (thanks Pig), or something of that nature. I will figure it out, and I'll get assistance when I run into a brick wall.

Quote:
Originally Posted by Grizzman View Post
FYI, the SS109 bullet has a ballistic coefficient very close to the 69 grain SMK, so that's what I used in Sierra Infinity. At 2900 fps with the scope (in P.E.P.R mount) zeroed at 25 yards, the impact is 1.3" high at 50, 3" high at 100, 3.5" high at 150, 2.6" high at 200, zeroed again at 250 yards, and 4.4" low at 300 yards. This allows for hits within + or - 4.5" from POA from the muzzle out to 300 yards.
I forgot to mention that my XM855 is the standard 62grain green tip variety (Muzzle velocity: 3104 fps Muzzle energy: 1326 ft/lbs). Now, I'll be trying to figure out the exact same graph for the XM855. Again, more of my "noviceness" in re: ballistics, etc. I hope to learn a lot here.

Quote:
Originally Posted by Grizzman View Post
With a couple exceptions, I run either irons or Aimpoints on all semi-auto rifles....especially carbines. Magnified scopes are only used when developing handloads for them.
I'm beginning to think that's what I should have done on this. Just install and sight in a good BUIS. Which I might eventually do, but I'd like to figure this out (with the scope) and learn from it. After that, maybe I will switch to the BUIS an preserve the scope for a longer range rifle.

Thanks very much! Happy 4th!
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  #55  
Old 07-01-2016, 05:33 PM
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Slip back to 50 or, if necessary, 25 yards. If you get consistent but low groups there, there is something wrong with the sights or the nut behind the rifle.
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  #56  
Old 07-01-2016, 05:42 PM
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Originally Posted by TLE2 View Post
Slip back to 50 or, if necessary, 25 yards. If you get consistent but low groups there, there is something wrong with the sights or the nut behind the rifle.

OK, thanks!
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