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Posted: 11/21/2009 2:43:57 AM EDT
| I have a bushmaster xm15. The twist rate on the barrel is 1:9. The ammo that I am using is federal 55 grain. The optic that I have is a Vortex Strikefire mounted on the upper receiver not the carrying handle. What kind of shot group at 100 yards can I expect with this kind of set up? I know that there are alot of other factors involved, but just on average. |
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Quoted: Quoted: Benched, I would expect 2-3 MOA, with ammo being the limiting factor. What type of ammo you think might tighten it up a little? I shoot Hornady 55-grain TAP and got 1" groups at 100 yards from my 16" 1:9 barrel. Unfrtunately, TAP is pretty pricey stuff, and is kind of hard to come by... The thing to do is shoot a box each of a bunch of different ammo. I have several thousand rounds of PRVI M855, which shoots 2 MOA out of my gun. I'm happy with that price/performance ratio. I also have some TAP ammo because I enjoy seeing small groups on paper. I know I could get smaller groups by handloading, but I'm not on that bus yet - sadly. |
| One thing you guys have to remember is the dot on the strikefire is 4moa. Sure you can get a group but if you cant see what your shooting at why bother. Its like any other red dot to me, sure you can shoot well with it but you'll never get a great group at a 100 with it. |
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Quoted:
Its like any other red dot to me, sure you can shoot well with it but you'll never get a great group at a 100 with it. There are those who claim that when using an Aimpoint (or other red dot sight) with a four minute of angle dot, that it is not possible to shoot groups that are smaller than four minutes of angle in extreme spread. One such person has gone so far as to claim that groups shot from 100 yards using an Aimpoint with a 4 MOA dot will be “greater than 4 inches. Usually much greater.” As we shall soon see, such statements are completely false. To determine the level of precision obtainable when using an Aimpoint sight with a 4 MOA dot, I mounted an Aimpoint ML2 with a 4 MOA dot on one of my Krieger barreled AR-15s. This AR-15 is easily capable of producing consistent sub-MOA 10-shot groups at 100 yards when using a high magnification scope. Shooting with the Aimpoint sight was done from a bench-rest at a distance of 100 yards using NRA 200 yard High Power type targets that I scaled-down for 100 yards. (The aiming black is approximately the same width as a human head.) Sighting was done using the whole dot centered on the bullseye. Three 10-shot groups were fired in a row for evaluation. 
Zeroing the Aimpoint sight at 100 yards was conducted during a down-pour with 20-25 mph winds. The first two 10-shot groups were also fired under these conditions. The first 10-shot group had an extreme spread of 1.41”. 
With another couple clicks of windage and elevation adjustment, the second 10-shot group had all shots going into the X-ring. The extreme spread for this group was 1.19”. 
Just as quickly as the down-pour had started, the rain stopped, the winds died down and the sun began shining again. I posted a new and dry target on the 100 yard backer and continued shooting. The third 10-shot group had an extreme spread of 1.14”. The average extreme spread for all three of the 10-shot groups was 1.25”. 
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