A firearm is provided comprising a body which defines a magazine well. The well has a rear wall and a first side wall integrated with the body. A front wall is detachable from the body and in part defining the well. Further a second side wall is detachable from the body and in part defining the well.

An adapter for coupling ammunition magazines together comprises a structure formed to include a first interior pocket having an opening facing in a first direction, and a second interior pocket having an opening facing in a second direction opposite the first direction. The first interior pocket is configured to receive a base of a first magazine, while the second interior pocket is configured to receive a base of a second magazine. To enable receipt of a magazine base by a pocket and a tight, secure fit within the pocket, the first interior pocket has an interior dimension slightly less than a corresponding exterior dimension of the base of the first magazine, and the second interior pocket has an interior dimension slightly less than a corresponding exterior dimension of the base of the second magazine.

An adapter for coupling ammunition magazines together comprises a structure formed to include a first interior pocket having an opening facing in a first direction, and a second interior pocket having an opening facing in a second direction opposite the first direction. The first interior pocket is configured to receive a base of a first magazine, while the second interior pocket is configured to receive a base of a second magazine. To enable receipt of a magazine base by a pocket and a tight, secure fit within the pocket, the first interior pocket has an interior dimension slightly less than a corresponding exterior dimension of the base of the first magazine, and the second interior pocket has an interior dimension slightly less than a corresponding exterior dimension of the base of the second magazine.

A spring comprises a continuous wire member formed into a plurality of coils along a central axis. Each of the plurality of coils comprises a plurality of straight portions extending between bend portions each extending from one of the straight portions. The plurality of coils form a first spring body and a second spring body, each spring body comprising at least three coils and having a first end and a second end with the first end of the second spring body connected to the second end of the first spring body. In an unloaded state the first spring body has a first unique pitch distance between bend portions of each pair of adjacent coils and the first unique pitch distance decreases from the first end of the first spring body to the second end of the first spring body, and the second spring body has a second unique pitch distance between bend portions of each pair of adjacent coils and the second unique pitch distance increases from the first end of the second spring body to the second end of the second spring body.

A firearm is provided comprising a body which defines a magazine well. The well has a rear wall and a first side wall integrated with the body. A front wall is detachable from the body and in part defining the well. Further a second side wall is detachable from the body and in part defining the well.

A firearm is provided comprising a body which defines a magazine well. The well has a rear wall and a first side wall integrated with the body. A front wall is detachable from the body and in part defining the well. Further a second side wall is detachable from the body and in part defining the well.

A gas turbine engine comprises a main compressor section having a high pressure compressor with a downstream discharge, and more upstream locations. A turbine section has a high pressure turbine. A tap taps air from at least one of the more upstream locations in the compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses air downstream of the heat exchanger, and delivers air into the high pressure turbine. An intercooling system for a gas turbine engine is also disclosed.

The present disclosure provides apparatus for coupling an item to another item. The apparatus comprises a coupler mounted on the item and comprising a mating face having a plurality of catches thereon, the plurality of catches comprising at least one complementary pair of catches positioned and shaped to be engaged with corresponding catches of another coupler having an identical mating face when mating faces of two couplers are facewise engaged with and rotated relative to each other to align with each other. The coupler may be implemented as a floor plate of a magazine, as a clip, or in other forms.

The present disclosure provides apparatus for coupling an item to another item. The apparatus comprises a coupler mounted on the item and comprising a mating face having a plurality of catches thereon, the plurality of catches comprising at least one complementary pair of catches positioned and shaped to be engaged with corresponding catches of another coupler having an identical mating face when mating faces of two couplers are facewise engaged with and rotated relative to each other to align with each other. The coupler may be implemented as a floor plate of a magazine, as a clip, or in other forms.

Magazine release button interference pin assembly and AR-style lower receiver functions to prevent the depression of the magazine release button on an AR-style rifle while the upper receiver is closed or locked onto the lower receiver. Magazine release button interference pin assembly and AR-style lower receiver prevents magazine release and reloading while the upper receiver is closed or locked onto the lower receiver. Magazine release button interference pin assembly and AR-style lower receiver is a magazine release button interference pin assembly as well as a specially machined lower receiver to accept the magazine release button interference pin assembly. Magazine release button interference pin assembly includes a special magazine release button interference pin with at least two protrusions, a spring, and a retaining pin.