Which gas block do I use to replace my stock front sight? Will the 10" rail completly cover the gas block? Is there any other parts that I will need to install the ST 10" rail?

Spike's does not currently carry a full length low profile gas block, only micro gas blocks. A full length block would be required to cover the taper slots cut into the barrel for the pinned front sight base.

Since you said M4 LE, that is carbine length gas and a 9" or longer rail will cover the low profile gas block.

You will need the appropriate tools, vise, and vise block to take off your barrel and swap from handguards to a rail system.

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Would one of your ST micro gas blocks work on my M4 LE?

It will work, but it would leave the forward taper slot on the barrel exposed. If you are going to put a rail that is longer than the 9" on there it won't be visible, but I would suggest applying some cold blue to the exposed slot.

You need either a Larue low profile, or a Centurion Arms low profile. I think the Centurion is a copy of the Larue, but it get's pinned along as one set screw on the bottom,, were as the Larue just has two set screw's. They both cover up the bare barrel mark's left behind.


Here's a pic of the Centurion.

Where is the hole for the taper pin on that block?