Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is larger than that of a standard M16/M4. A bolt carrier can have a bolt that has a double cut cam having an unlocking cam surface that has sufficient dwell increase to delay a start of unlocking when the bolt carrier is used in an M4 carbine. A stepped extractor pin may be provided that prevents disengagement of the extractor pin. A tube can be configured to provide gas from a barrel of the firearm to the piston via the carrier key. The tube can have a heat radiator formed from triangular shaped threads on at least a portion of the tube. A piston on the bolt and can have a plurality of rings including pairs of mating rings that are formed and maintained as a matched pair.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is larger than that of a standard M16/M4. A bolt carrier can have a bolt that has a double cut cam having an unlocking cam surface that has sufficient dwell increase to delay a start of unlocking when the bolt carrier is used in an M4 carbine. A stepped extractor pin may be provided that prevents disengagement of the extractor pin. A tube can be configured to provide gas from a barrel of the firearm to the piston via the carrier key. The tube can have a heat radiator formed from triangular shaped threads on at least a portion of the tube. A piston on the bolt and can have a plurality of rings including pairs of mating rings that are formed and maintained as a matched pair.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is larger than that of a standard M16/M4. A bolt carrier can have a bolt that has a double cut cam having an unlocking cam surface that has sufficient dwell increase to delay a start of unlocking when the bolt carrier is used in an M4 carbine. A stepped extractor pin may be provided that prevents disengagement of the extractor pin. A tube can be configured to provide gas from a barrel of the firearm to the piston via the carrier key. The tube can have a heat radiator formed from triangular shaped threads on at least a portion of the tube. A piston on the bolt and can have a plurality of rings including pairs of mating rings that are formed and maintained as a matched pair.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is larger than that of a standard M16/M4. A bolt carrier can have a bolt that has a double cut cam having an unlocking cam surface that has sufficient dwell increase to delay a start of unlocking when the bolt carrier is used in an M4 carbine. A stepped extractor pin may be provided that prevents disengagement of the extractor pin. A tube can be configured to provide gas from a barrel of the firearm to the piston via the carrier key. The tube can have a heat radiator formed from triangular shaped threads on at least a portion of the tube. A piston on the bolt and can have a plurality of rings including pairs of mating rings that are formed and maintained as a matched pair.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is larger than that of a standard M16/M4. A bolt carrier can have a bolt that has a double cut cam having an unlocking cam surface that has sufficient dwell increase to delay a start of unlocking when the bolt carrier is used in an M4 carbine. A stepped extractor pin may be provided that prevents disengagement of the extractor pin. A tube can be configured to provide gas from a barrel of the firearm to the piston via the carrier key. The tube can have a heat radiator formed from triangular shaped threads on at least a portion of the tube. A piston on the bolt can have a plurality of rings including pairs of mating rings that are formed and maintained as a matched pair.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is larger than that of a standard M16/M4. A bolt carrier can have a bolt that has a double cut cam having an unlocking cam surface that has sufficient dwell increase to delay a start of unlocking when the bolt carrier is used in an M4 carbine. A stepped extractor pin may be provided that prevents disengagement of the extractor pin. A tube can be configured to provide gas from a barrel of the firearm to the piston via the carrier key. The tube can have a heat radiator formed from triangular shaped threads on at least a portion of the tube. A piston on the bolt and can have a plurality of rings including pairs of mating rings that are formed and maintained as a matched pair.

Abstract: A firearm can have a backbone, a barrel, a swinging wedge, and a barrel latch, in accordance with one or more embodiments. The barrel latch can be in mechanical communication with the swinging wedge. The barrel latch can have a first position and a second position and the swinging wedge can be configured to maintain attachment of the barrel to the backbone when the barrel latch is in the first position and is configured to release the barrel from the backbone when the barrel latch is in the second position. Thus, the firearm can provide quick barrel changes. Other features enhance the reliability and utility of the firearm.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is at least approximately 1.3 times that of a standard M16/M4. A piston can be formed on the bolt and can have a plurality of rings that are configured to cooperate with the piston to mitigate gas leakage past the piston. Each of the rings can have a key formed thereon and a gap formed therein such that the gap of one ring is configured to receive at least a portion of the key of another ring. The bolt carrier can have a double cut cam.

Abstract: An improved catheter is provided. The catheter may include a deflectable member located at a distal end of the catheter. The deflectable member may comprise an ultrasound transducer array. The catheter may include a lumen extending from a proximal end of the catheter to the distal end. The lumen may be used to deliver an interventional device to a point distal to the distal end of the catheter. The deflectable member may be selectively deflectable in a pivot-like manner through an arc of at least 90 degrees. In embodiments where the deflectable member includes an ultrasound transducer array, the ultrasound transducer array may be operable to image both when aligned with the catheter and when pivoted relative to the catheter. When pivoted relative to the catheter, the ultrasound transducer array may have a field of view distal to the distal end of the catheter.

Abstract: A firearm can have a backbone, a barrel, a swinging wedge, and a barrel latch, in accordance with one or more embodiments. The barrel latch can be in mechanical communication with the swinging wedge. The barrel latch can have a first position and a second position and the swinging wedge can be configured to maintain attachment of the barrel to the backbone when the barrel latch is in the first position and is configured to release the barrel from the backbone when the barrel latch is in the second position. Thus, the firearm can provide quick barrel changes. Other features enhance the reliability and utility of the firearm.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is at least approximately 1.3 times that of a standard M16/M4. A piston can be formed on the bolt and can have a plurality of rings that are configured to cooperate with the piston to mitigate gas leakage past the piston. Each of the rings can have a key formed thereon and a gap formed therein such that the gap of one ring is configured to receive at least a portion of the key of another ring. The bolt carrier can have a double cut cam.

Abstract: An improved catheter is provided. The catheter may include a deflectable member located at a distal end of the catheter. The deflectable member may comprise an ultrasound transducer array. The catheter may include a lumen extending from a proximal end of the catheter to the distal end. The lumen may be used to deliver an interventional device to a point distal to the distal end of the catheter. The deflectable member may be selectively deflectable in a pivot-like manner through an arc of at least 90 degrees. In embodiments where the deflectable member includes an ultrasound transducer array, the ultrasound transducer array may be operable to image both when aligned with the catheter and when pivoted relative to the catheter. When pivoted relative to the catheter, the ultrasound transducer array may have a field of view distal to the distal end of the catheter.

Abstract: An improvement setter and method of operation for maintaining and reconfigurating the shape of a malleable pattern used in molding of parts. The setter includes an arrangement for arranging the pattern against the setter using vacuum.

Abstract: An injection mold for forming a pattern for use in investment casting having mold sections carrying two pattern-forming surfaces and a translatable third pattern-forming element movable on a mold section. The mold also includes an inner core. Parting lines are located at inconspicuous locations by sizing and shaping the mold sections. The method of use of the injection mold includes employing an arrangement for facilitating lower mold section and for raising the inner core to facilitate its removal.

Abstract: An injection mold for forming a pattern for use in investment casting having mold sections carrying two pattern-forming surfaces and a translatable third pattern-forming element movable on a mold section. The mold also includes an inner core. Parting lines are located at inconspicuous locations by sizing and shaping the mold sections. The method of use of the injection mold includes employing an arrangement for facilitating lower mold section and for raising the inner core to facilitate its removal.