Colt Front Sight Posts Colt has produced at least four different front sight posts for use on their AR-15/M16/M4 series of weapons. The front sight posts can be roughly categorized according to their basic shape, (square or round) their profile, (straight or tapered) and their height, (short or tall.) The height of the posts are measured from the top of the sight post down to the top of the “flange” of the sight post.
The sight post with the part number SP64507 has a short, square and straight configuration. This post has a measured nominal height of approximately 0.270”
SP64507
Part number SP64665 also has a short and square post, but differs from the above sight post in that it has a tapered shape to it; broader at the base and narrowing at the top. The measured nominal height of this post is also approximately 0.270”.
SP64665
Shown below are the square, short/straight and short/tapered sight posts side by side for comparison.
The sight post associated with the M16/M16A1 series of rifles has a round shape and is also short and tapered. The part number for this post is SP61706. It is slightly shorter than the two posts described above with a measured nominal height of approximately 0.260”.
SP61706
The last sight post is Colt’s tall sight post which has a measured nominal height of approximately 0.300”. It has a square and straight configuration. Its part number is SP62447.
SP62447
Here is a pic with the round sight post and the tall sight post side by side for comparison.
The original round sight post has five equally spaced notches around the sight post flange for elevation adjustment. Each notch corresponds to approximately 1 MOA of elevation (when used with a rifle length sight radius). The other three sight posts all have four elevation notches on their flanges corresponding to approximately 1.25 MOA of evlevation (with the rifle length sight radius).
Bushmaster makes a front sight post that has a nominal height of 0.310”.
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