Can we make a thread that gives the maximum effective range of various length uppers? I’m building an SBR and that has prompted me to ponder this. We’ll define maximum effective range as distance at which you can expect reliable fragmentation.
I’m sure as a forum we can come up with some adequate figures for the M193 round.
I’m sure this would be helpful to many. I know I’d like to know
Lengths:
20"
18"
16"
12.5"
11.5"
10.5"
7.5"
Thanks to those who can be of help.
I’ll try and up date this post with the info as we go.
First of all, you need to define what you mean by “effective” range. That’s going to mean different things to different people. For example, for some people it refers to the distance at which you can expect reliable fragmentation from a particular load. The chart below gives you that range from three different barrels for the 75 grain TAP loads.
As for M193, the distance would be approximately 135 yards for a 20" barrel, 105 yards for a 16" barrel and 75 yards for a 14.5" barrel.
Molon, did you explain elsewhere how you determine the maximum range of fragmentation for various loads? I’d like to duplicate something like this for my own loads.
Determine the fragmentation threshold for the bullet being used (the velocity above which you can reliably expect fragmentation to occur.) I use 2,250 fps for the Hornady 75 grain BTHP. The generally accepted figure for the 55 grain FMJ bullet used in M193 is 2700 fps.
Determine the muzzle velocity of the load being used from your particular barrel, for example 2820 fps for 75 grain 5.56 TAP from a 20" Colt barrel.
Using a quality external ballistics program, find the maximum distance to which the bullet stays above the fragmentation threshold. Again using the 5.56 TAP load as an example, the distance would be 230 yards.
