Abstract: Disclosed herein is a modified upper receiver assembly and method of assembly, which in one form is operatively configured to be fitted to a conventional lower receiver of a rifle so the user can use their normal lower receiver having a pistol grip, trigger assembly and butt stock. The upper receiver is configured to provide a blowback bolt assembly of larger mass than would be possible with similar density materials of a bolt fitted within an upper receiver conventionally made for said lower receiver.

Abstract: Disclosed herein is a modified upper receiver assembly, which in one form is operatively configured to be fitted to a conventional lower receiver of a rifle so the user can use their normal lower receiver having a pistol grip, trigger assembly and butt stock. The upper receiver is configured to provide a blowback bolt assembly of larger mass than would be possible with similar density materials of a bolt fitted within an upper receiver conventionally made for said lower receiver.

Abstract: A method for adjusting the static attitude of a head suspension by scanning a region of the head suspension with a laser. A head suspension having a gimbal region is provided that permits a head slider attached thereto to gimbal about pitch and roll axes in response to fluctuations in an air bearing over which the head slider flies. One or more predetermined regions of the head suspension are irradiated by a laser beam by scanning the laser beam across the head suspension regions to affect the static attitude of the head suspension. In a preferred embodiment, a plurality of parallel spaced apart lines are scanned on the leaf spring arms of a flexure with the laser to correct pitch errors in static attitude, and a plurality of parallel spaced apart lines are scanned with the laser in the cross section attached to the leaf spring arms to correct roll errors in static attitude. One or both sides of the head suspension can be scanned to create a desired pitch and/or roll correction.