The 'F' Marked AR/MSR Front Sight

The 'F' Marked AR/MSR Front Sight

Gus Norcross, originally trained on National Match rifles and pistols by the National Guard Marksmanship Training Unit specializes in Garands, M14s and 1911s at his small shop on the coast of Maine. His website is www.angusarms.com. He will be offering gunsmithing tips and tricks on Fridays.

Here is a typical scenario: You get a killer deal on a used AR-style carbine at the local gun emporium and you rush to the range to test-fire and zero your new prize. Upon dialing in a typical 25-yard military zero with the detachable carry handle or a folding backup rear sight you notice the front sight post is screwed almost completely out of the front sight housing.

The problem here is that the manufacturer assembled the rifle with a standard early front sight assembly designed for rifles with integral carry handles rather than one meant for flat top receivers. This situation may not be a real issue as long as the rifle zeroes but it certainly looks funny and it isn't right.

When Colt designed the original flat top upper receivers for the M4 carbine they couldn't just hack off the carry handle and install a rail. The top of the receiver had to be strengthened to maintain structural integrity.


This means the detachable carry handle sat a bit higher than a normal integral carry handle and the front sight was a bit too low. As Patrick Sweeney points out in his book Gunsmithing The AR-15, Colt could have modified the carry handle for an easy fix, but instead they chose to alter the height of the front sight housing.


These new front sights were stamped with a letter "F" to differentiate them from the older models. Front sight deck height will undoubtedly vary slightly between commercial manufacturers but the difference between old and new runs in the .080"-.090" range.


Turning the front sight counterclockwise to raise it may cause the sight flange to rise above flush with the flat surface of the housing.

At this point, the sight post may only be retained by a few threads. Replacing a pinned front sight housing is possible but difficult without proper tooling. The easy fix here is to purchase a higher front sight post. Bushmaster Firearms sells one that is .040" higher than a standard A2 style, part number F1003228, available from their website for $5.50.

Next time a rifle manufacturer claims its M4 carbine clone is "mil-spec" and they don't use the higher front sight housing the military issues, you'll know there is a bit of BS involved in their advertising.


Front sights with \"F\"

Front sights with the proper deck height to match M4 upper receivers are marked with the letter "F". Earlier sights were made for the fixed-handle A1 or A2 versions

Front Site

You may find the front sight must be almost completely backed out when the front sight tower and upper receiver are mismatched.

Recommended for You

No one can restore receptivity to another Trump term with these disaffected gun owners but the president himself. 2nd Amendment

2020 is Trump's to Blow with Gun Owners

David Codrea - July 09, 2019

No one can restore receptivity to another Trump term with these disaffected gun owners but the...

CZ-USA's handy CZ 527 7.62x39mm bolt gun now accepts a sound suppressor. Rifles

Suppressor-Ready CZ 527 Review

David M. Fortier - July 22, 2019

CZ-USA's handy CZ 527 7.62x39mm bolt gun now accepts a sound suppressor.

Customers who purchase any new Mauser or J.P. Sauer and Sohn rifle from an authorized dealer's in-store inventory will receive a coupon code for 50% off the online purchase of one Minox optic. Industry

Blaser USA Announces Special Promotion in Partnership with Minox Optics

Blaser USA - July 19, 2019

Customers who purchase any new Mauser or J.P. Sauer and Sohn rifle from an authorized dealer's...

See More Recommendations

Popular Videos

M134 Mini-Gun

M134 Mini-Gun

While filming the 2018 season of Guns&AmmoTV we had the unique opportunity to fire the M134 Minigun.

New Bushnell Prime 1700 and Nitro 1800 Rangefinders

New Bushnell Prime 1700 and Nitro 1800 Rangefinders

Jake Edson of Bushnell Optics tells OSG's Lynn Burkhead about the brand new Prime 1700 and Nitro 1800 rangefinders.

Hornady

Hornady's New A-Tip Line of Match Bullets

Hornady Manufacturing, has developed a new line of match bullets. The A-Tip is designed for precision and long-range shooting.

See more Popular Videos

Trending Stories

This will be the first of many investigative reports about the NRA by Firearms News. 2nd Amendment

Firearms News Investigates the NRA: Part 1

Nedd Scott - July 18, 2019

This will be the first of many investigative reports about the NRA by Firearms News.

CRKT makes 17 different knife models exclusively for Ruger, from fixed hunting knives to tactical folders, and many of their models are offered in several different styles. Accessories

Ruger CRKT Knives Review

James Tarr - July 08, 2019

CRKT makes 17 different knife models exclusively for Ruger, from fixed hunting knives to...

Governor Northam is calling a special session of the General Assembly on Tuesday, July 9th, to do nothing but pass more gun control! 2nd Amendment

Virginia Governor Northam Declares War on Gun Owners

Virginia Citizens Defense League - July 09, 2019

Governor Northam is calling a special session of the General Assembly on Tuesday, July 9th, to...

See More Stories

More How-To

Sometimes an armorer may find it necessary to remove the front sight housing on an AR-15/M16 type How-To

How to Remove an AR Front Sight

Gus Norcross - March 20, 2013

Sometimes an armorer may find it necessary to remove the front sight housing on an AR-15/M16...

Bowling Pin Shooting began as a demonstration technique and quickly evolved into an annual shooting match. How-To

The Sport of Bowling Pin Shooting

Patrick Sweeney - March 20, 2019

Bowling Pin Shooting began as a demonstration technique and quickly evolved into an annual...

I am fortunate enough to live in a semi-rural area, and am one of the few on my road who doesn't How-To

Front-Yard Pistol Range: Bad Idea

Robert W. Hunnicutt - February 04, 2015

I am fortunate enough to live in a semi-rural area, and am one of the few on my road who...

See More How-To

GET THE MAGAZINE Subscribe & Save

Temporary Price Reduction.

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW OUR CURRENT ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.