From the author's README on Thunderstore

3 Halo sniper rifles for Master Chief.

Halo 2 Sniper
Halo 3 Sniper
Halo Reach Sniper

Dependencies

You must install Skaterize for this mod to work correctly.

Install

Install through the ReSkate launcher and enable Skaterize and Halo Sniper Pack.
Equip a rifle under Apparel → Miscellaneous 2 or Miscellaneous 3.

Slot compatibility

Use slot 2 or 3 for the rifle to be visible with Master Chief.

Changelog

1.0: Initial release.
1.0.1: ReadMe updates

Known Issues

Some scopes have a gap if closely inspected.
Some barrels have an odd bend to them if closely inspected.

Credits

Sniper rifle model on Sketchfab.

Install Halo Sniper Pack

You need ReSkate and your own copy of skate. on Steam.

Open ReSkateLauncher.exe and go to MODS.
Search for Halo Sniper Pack and click install. The launcher also installs anything it depends on.
Press PLAY. In game, the MODS tab of the ReSkate menu (Insert) turns it on and off.

Or install it by hand: download the .zip and drop it on the launcher window, or unzip it into its own folder in Mods\ beside Skate.exe.

It needs

Skaterize by Kori_ReSkate

Maps show up in the ReSkate menu's level list. To join a server running a custom map, you need the same map installed. If the game won't load after installing, see known issues.

skatemods doesn't host or review this mod. The download comes straight from Thunderstore. Only install mods you trust, because scripts can run code.