Correct front sight post for M4

[Djstorm100]

I need to order one as I broke mind (I have to be the most unlucky bastard, freak accident)

Looking at brownells Colt has 2. Doesn't give much description in which one is right or wrong. I'm thinking the 2nd one is right but wanted to confirm.

http://www.brownells.com/rifle-parts/sights/front-sights/ar15a4-front-sight-post-prod4770.aspx?avs|Make_3=AR-15%2fM4

http://www.brownells.com/rifle-parts/sights/front-sights/sight-post-front-16-barrel-prod4769.aspx?avs|Make_3=AR-15%2fM4

[_Stormin_]

If this is for a carbine, the second one SP64665. That said, IIRC both will fit.

[556Cliff]

I tried to order the FSP in your second link from Brownells a couple of years ago. They sent me the standard FSP from your first link in a bag with the part number for the tapered carbine FSP.

I went and ordered the tapered carbine FSP from SAW and received the correct part.

Either FSP should work, what rifle do you have exactly?

[Djstorm100]

I tried to order the FSP in your second link from Brownells a couple years ago. They sent me the standard FSP from your first link in a bag with the part number for the tapered carbine FSP.

I went and ordered the tapered carbine FSP from SAW and received the correct part.

Either FSP should work, what rifle do you have exactly?

DD m4v9 16" barrel
SAW?

[Molon]

Colt Front Sight Post Primer


Colt currently offers four different front sight posts for use on their AR-15/M16 family of weapons. The front sight posts can be 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 nominal height of 0.270”

SP64507
http://www.box.net/shared/static/sfemup3tje.jpg


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 height of this post is also 0.270”.

SP64665
http://www.box.net/shared/static/3ixso44u8q.jpg


Shown below are the square, short/straight and short/tapered sight posts side by side for comparison.

http://www.box.net/shared/static/ym1n1ar5e5.jpg

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 height of 0.260”.

SP61706
http://www.box.net/shared/static/9fzjm5e8tq.jpg


The last sight post is Colt’s tall sight post which has a nominal height of 0.300”. It has a square and straight configuration. Its part number is SP62447.

SP62447
http://www.box.net/shared/static/sqgsbhvqc6.jpg


Here is a pic with the round sight post and the tall sight post side by side for comparison.

http://www.box.net/shared/static/fplxodhst6.jpg


The original round sight post has five equally spaced notches around the sight post flange for elevation adjustment. Each notch corresponds to 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 1.25 MOA of evlevation.

http://www.box.net/shared/static/d2t6yoj8as.jpg



Bushmaster makes a front sight post that has a nominal height of 0.310”.

http://www.box.net/shared/static/tsdaq4fnkw.jpg





"F" Marked Front Sight Base


There is no difference in the overall height of an “F” marked front sight base and a standard front sight base. The only difference between the two front sight bases is the height of the sight “shelf” above the top of the barrel.


http://www.box.net/shared/static/uei1uar8kw.jpg



http://www.box.net/shared/static/2d520zm04w.jpg



The front sight post on a standard Colt front sight base will bottom-out in the sight well at approximately 24 clicks below flush. On an “F” marked front sight base the sight “shelf” is a whopping 0.040” higher than on a standard front sight base. That means you might have to turn your front sight post down approximately 6 clicks further with an “F” marked front sight base than on a standard front sight base. (6 whole clicks difference. Oh, the inhumanity!) So unless your front sight post is set at 18 clicks below flush with a standard front sight base, using an “F” marked front sight base on a 20" barrel will be a non-issue.





.....

[556Cliff]

DD m4v9 16" barrel
SAW?

Specialized Armament Warehouse.

Either the standard rifle FSP or the tapered carbine FSP will work for you. The tapered carbine FSP will give you a slightly narrower at the tip "rifle like" sight picture though.

The FSP you had before (the one that broke) was a standard rifle FSP.

If you try and order the tapered carbine FSP from Brownells you might just end up with the standard rifle FSP anyway... Good luck to you.

[Djstorm100]

Specialized Armament Warehouse.

Either the standard rifle FSP or the tapered carbine FSP will work for you. The tapered carbine FSP will give you a slightly narrower at the tip "rifle like" sight picture though.

The FSP you had before (the one that broke) was a standard rifle FSP.

If you try and order the tapered carbine FSP from Brownells you might just end up with the standard rifle FSP anyway... Good luck to you.


The front sight is a pic mount from DD. looking at the sight it apperas to be just what you stated a rifle. Sadly I didn't know there was a difference because (apparently) I've been shooting rifle irons for so long.

[556Cliff]

The front sight is a pic mount from DD. looking at the sight it apperas to be just what you stated a rifle. Sadly I didn't know there was a difference because (apparently) I've been shooting rifle irons for so long.

A little info on the tapered carbine FSP from the Specialized Armament website.

"Designed by Colt Engineering to create the same sight picture between rifles and carbines.

Used on many Colt export model carbines - not officially used by the US Military.

Center drilled at base for identification purposes."