Front sight posts

[rmeyer]

Ok I built 2 M16a1 clones. The first is about 90+% original Colt parts from the late 60s to early 70s. the 2nd about 45%. They both have the same FSB and posts but my first gun I have the post all the way down at 100 yards. Was there a difference in length in sight post used in the early guns. Both have the 5 slots for adjusting. Any Help?

[ClassIIIGunsmith]

Seems you need to bring it up to 300 yds so the long range flip is correct at 600 yds. I have a legal Colt SP1 converted to f/a in 1980 (3 years after I bought it) and I have not touched the sights on it. The rifle should be shooting 3" high at 100 yds in semi. As long as you are using the A1 circle post instead of the A2 square post there is no difference because as I recall the A2 post is taller or its the other way around (I don't absolutely remember). Hope this helps

[rmeyer]

Both rifles have the same front sight post. This is what has me confused..

[ClassIIIGunsmith]

Both rifles have the same front sight post. This is what has me confused..

The rifles were never meant to be dead on at 100 yds I went to the range the other day and for the first time I touched the front sight brought it down to the lowest point and it was shooting 1" high. your issue is the depth that the post can go down is too short to be hitting dead on at 100 yds as for the rifle was intended to be shooting 3" high at 100 yds which is dead on at 300 yds. So I would recommend that you bring the sight up to hit dead on at 300 yds so the whole issue is resolved and both rifles shoot the same. That is what I recommend you do to solve your issue. Just remember to aim 3' lower to hit dead on at 100 yds.

[rmeyer]

I decided to remove the front sight post and detent for inspection. I dropped cleaning solution into the hole and it didn't flow through the hole on the bottom. I use a tooth pick and removed a lot of sludge then used a pipe cleaner to give it a good cleaning. I put it back together and headed back to the range. Final results I was able to adjust the sight and now I'm hitting around 3" high at 100 yds. I believe the different heights of the sight post is due to manufacturers, This rifle has a early Colt FSB and a Colt a1 receiver. The rifle I was comparing it to has an early Colt FSB and an aftermarket receiver. Difference in manufacturing specs. Like comparing apples to oranges.

[JasonB1]

I believe the different heights of the sight post is due to manufacturers, .

Colt has made different post heights:


https://www.m4carbine.net/showthread...ont-sight-post