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Posted: 3/29/2006 10:22:20 PM EDT
MaverickMkii here on AR15.com calculated bullet trajectories for different AR rounds to assess fragmentation capabilities of the rounds in different length barrels. I took his M-193 Flight Path data for 16" barrels which assumes a 50yd 0, and plotted it. It was based upon the std iron sights which are 2.6" above the bore center-line. That data is the blue line below.

My handle mounted scope is an additional 1" above that and I was curious what the extra 1" in scope height did to the 'numbers'. I plotted his data starting it at 3.6" below the sight-line and again used 50yds as my zero point which canted the flight path of the bullets. That data is the red line below.

Note: I used a simple approach and just assumed that the flight paths would be the same for both sight elevations even though the scope's slightly elevated angle caused means that this data is only an approximation of the true ballistic flight path.

It does give me pause to think that for 25 - 325 yds, maybe the higher sight gives one a more desirable trajectory. The data looks to me like from 50yds - 275yds, the bullet is between sight-line and just over + 3" the whole way. That looks like minute of coffee cup to me. What do you all think?

(No wonder I couldn't miss at the range last weekend.)

Link Posted: 3/29/2006 10:26:59 PM EDT

Originally Posted By COSteve:
MaverickMkii here on AR15.com calculated bullet trajectories for different AR rounds to assess fragmentation capabilities of the rounds in different length barrels. I took his M-193 Flight Path data for 16" barrels which assumes a 50yd 0, and plotted it. It was based upon the std iron sights which are 2.6" above the bore center-line. That data is the blue line below.

My handle mounted scope is an additional 1" above that and I was curious what the extra 1" in scope height did to the 'numbers'. I plotted his data starting it at 3.6" below the sight-line and again used 50yds as my zero point which canted the flight path of the bullets. That data is the red line below.

Note: I used a simple approach and just assumed that the flight paths would be the same for both sight elevations even though the scope's slightly elevated angle caused means that this data is only an approximation of the true ballistic flight path.

It does give me pause to think that for 25 - 325 yds, maybe the higher sight gives one a more desirable trajectory. The data looks to me like from 50yds - 275yds, the bullet is between sight-line and just over + 3" the whole way. That looks like minute of coffee cup to me. What do you all think?

(No wonder I couldn't miss at the range last weekend.)

img.photobucket.com/albums/v726/Coloradoglocker/Five.jpg



Most would consider a FLATTER trajectory more desirable...
Link Posted: 3/29/2006 10:28:14 PM EDT
That's pretty interesting.
Link Posted: 3/30/2006 5:43:29 AM EDT
Having played with this, I'd like to help. Found one advantage and one disadvantage, theoretically, in using a scope atop the sight handle.

The two curves are actually the same shape, just tilted by lowering one end of the red curve (high-mounted scope trajectory), pivoting on the 50yd zero point, and raising the downrange end of it. If the comparison is redrawn using a 250yd zero as that pivot point, with both curves meeting only there, you can see that the red curve would be a little lower than the blue one (iron sights trajectory) anywhere short of 250, and a little higher anywhere beyond.

In other words, the impact with a high scope mount lies closer to the point of aim from 100 to 300 yds. That gives a longer point blank range, but places your soldier's noggin another inch above cover.
Link Posted: 3/30/2006 6:13:37 AM EDT

Originally Posted By Dave_A:

Most would consider a FLATTER trajectory more desirable...



Absorootry!

I want the flattest trajectery possible inside of 250 yards! I can hold over a little out past that.
Link Posted: 3/30/2006 10:20:16 AM EDT
The trajectory of a M-193 bullet fired from a 16" AR barrel is not the function of any particular aim-point but rather the results of the forces acting upon the bullet. I.e. mass, velocity, aerodynamic drag, gravity, and wind velocity and it's vector to the bullet's flight path.

There is no sighting method in this universe that changes the trajectory of the bullet, but rather, one tries to 'optimize' the zero point to reflect the characteristics of the bullet's trajectory within one's particular ranges of interest.

My chart simply shows that, with my scope mounted 3.6" above the bore center-line and the rifle sighted to '0' at 50 yds, the trajectory of the M-193 bullet will not be more than about 3.5" above or below the sight-line all the way from the muzzle out to approximately 325 yds.
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