Modular rail system and firearm with modular rail system

1. A method for providing a modular rail system for an upper receiver of a weapon, comprising:

slidably inserting a plurality modular rails within channels located on top of an exterior surface of the upper receiver in a first direction;

sliding the plurality modular rails within an elongated channel intersecting the channels in a second direction; and

securing each one of the plurality of modular rails to the elongated channel via a pair of securement features located on each one of the plurality of modular rails, wherein at least two of the plurality of modular rails are secured to the elongated channel such that a gap is located between the at least two of the plurality of modular rails.

2. The method as in claim 1 , wherein the pair of securement features cannot be removed from the elongated channel unless they are aligned with a pair of the plurality of channels.

3. The method as in claim 1 , wherein the first direction is perpendicular to the second direction.

4. The method as in claim 3 , wherein the plurality of first features comprise a flange of an upper ledge portion and a flange of a lower edge portion defining the elongated channel extending in the second direction.

5. The method as in claim 1 , wherein the plurality modular rails have varying lengths.

6. The method as in claim 1 , wherein the plurality modular rails slide in at least two of the channels prior to sliding in the elongated channel in the second direction.