MSG90

The MSG90 is a militarized variant of the Heckler & Koch PSG1, that is both strengthened and lightened. The PSG1 and MSG90 share the same trigger group and adjustable trigger pull. The composite shoulder stock of the MSG90 is adjustable for height (cheek), length of pull (shoulder), and is smaller and lighter than that of the PSG1. Some MSG90s have a basic G3 barrel instead of the PSG1's heavy barrel, but remain free-floating. As a result, these particular MSG90s are capable of attaching a suppressor, which is an advantage over the PSG1.

The sighting system utilizes the multipurpose Weaver rail system rather than the STANAG 2324 claw mount for affixing sighting systems which can be purchased separately. This same rail mounting system is used on the HK21E, HK23E, and G41 (discontinued) series.

The barrel is weighted at the muzzle to aid harmonic stabilization of barrel whip to enhance accuracy. The addition of a flash suppressor adds to the overall length. Mexican produced MSG-90's feature a slightly longer barrel (1.1 inch) and the addition of a built in bipod, although it can be removed with the included tools.