AR Front Sight Removal/Installation help


January 25, 2012, 09:42 PM
I've got an M&P sport that I really like. It came with a fixed front sight, magpul flip rear sight, and a plastic handguard. I'd like to remove the front sight and install a magpul flip front sight so I can install a scope that's on it's way to me.

I assume I'll need to remove the plastic handguard and install some sort of picatinny rail system as well.

Can anyone walk me through the process?

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January 25, 2012, 09:56 PM
If the tower is utilizing standard pins - they will be driven out from left to right oriented to the firer. Be sure to save the pins and the sight tower for the particular barrel should you want to go back to it some day.

If you can't get a concavely cupped pin punch, a nail set punch (can't remember the #) will work well in not mushrooming the protruding portion which sometimes causes things to go south real fast.

January 25, 2012, 10:30 PM
I've read some things about gas tubes in the AR front that something I have to worry about here?

January 25, 2012, 10:31 PM
You won't see the fixed front sight through the scope, so leaving it on is not an issue. If you must remove the current gas block / front you'll need a new gas block as well. S&W mushrooms both sides of the FSB pins, so it's going to be a gunsmith removal in most cases. If you're dead set on a flip up front sight I'd just cut the current FSB down to a low profile, and get a handguard that covers it.

January 25, 2012, 10:53 PM
You might just want to consider a rail riser to bring the scope above the sight. You would need to replace the sight with a gas block if you remove it.

January 25, 2012, 11:22 PM
You will never notice the FSB through a scope.

January 26, 2012, 12:02 AM
front tower replaced with an integral flip up front sight gas block made just for this kind of thing? They are out there, not terribly expensive IIRC

January 26, 2012, 09:41 AM
Do NOT drive out the pins of a front sight base with a standard flat punch. There is a good chance they will mushroom and become extremely difficult to remove. There are special types of punches with a concave tip to prevent this.

January 26, 2012, 09:43 AM
You basically have to drive the tapered pins out the correct way. The gas tube is pinned in, and that roll pin needs to be removed also. Plus the flash hider removed to slip the various gas blocks on and off.

The new block should match the barrel diameter at the port, .750 is typical. Once done, a metal BUIS can be clamped on, and overall, likely won't be any lighter, but will be $75 to $150. This will not increase the value or accuracy of the rifle one whit, and have been known to loosen up and fall off when least expected. The flip up function will also be another additional task to perform precisely when you are wanting to take a shot and the defective optic is still in the way.

While some specialty rifles have a niche need for this, on the whole, it's a lot of money spent for very little actual return - the FSB is usually a small blur in the lower portion of the scope and doesn't affect its use anyway.

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