MFI SIG 556 / 550/1/2 Front Flip Up Sight / Price Includes S&H via USPS 1st Class Mail.

The front sight's dove tail must slide somewhat freely in the dove tail of the gas block.

Meaning: You should NOT have to use a hammer to drift the sight side to side, but it should also NOT be so loose as to slide easily. The right amount of friction is so that the sight drifts sideways via a significant amount of force using your fingers... i.e. nearly all of your might using both hands(tightest) to as easy as half of your strength (loosest). The idea here is that the sight has enough friction in the dove tail not to move during firing.

Failure to do this WILL result in the stripping of the cross-over bolt or the shearing of the roll pin inside the donut / round nut.

Hand fitting is required as the dove tails in the gas blocks vary from production to production. Hand fitting can be done via a small hand file used on the slanted edges of the sight's dove tail.

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How to install the roll pin in the front sight.

It is easy to mess up the roll pin when you first try to install it. Read below to avoid the pitfalls. Not all SIG 556 series weapons come with a front sight installed. So issues like this arise most often when the user is NOT first removing a similar front sight from the weapon and thus is completely unfamiliar with the requirements.

There is a first time for everything and that is a part of any weapons system.

When SIG installs these at the factory they have a special fixture or a second person to hold the weapon. While a fixture or third person is NOT required it sure makes it a lot easier. All you need is someone to hold the weapon while you hold the punch and hammer.

Be sure that the hole in the donut and spline are clean / free of metal shavings.

The most common mistake that leads to messing up a roll pin is not having the hole in the spline / adjustment bolt and the hole in the round / donut wheel lined up. You will have to use a punch or something to be absolutely sure of the alignment. Use a 1/16” punch or 1/16” drill bit or 1.5mm allen key… or look around the house and shop for something that fits through both.

The number of turns to get the holes lined up is between 2.5 and 3 full rotations (you have to look down the hole). The windage bolt should NOT go past the point of being flush with the outside edge of the donut.

It is a lot easier to file or grind down the roll pin at one end and then gently collapse the same end with a vice grips of pliers so that it just fits / sits in the hole of the donut. This will free up one hand. This is almost a requirement.

Lube the hell out of the roll pin and hole of the donut and spline.

Always start with your 1/16” punch (or whatever) 3/4 the way through to assure alignment. As you drive the roll pin in the punch will move out the opposite side.

Good luck...

These roll pins are specially made for us so, if you mess up the roll pin you can buy a spare from us on this page:

CLICK HERE FOR SIG FRONT SIGHT ROLL PIN