Adjustable gas block for firearm
An adjustable gas block for a firearm comprises a housing adapted to be attached to a barrel of the firearm. The housing has a first passageway adapted to be aligned with a gas port in a barrel of the firearm and a second passageway adapted to receive a gas tube of the firearm, such that a bore of the barrel, the gas port of the barrel, the first passageway, and the gas tube are in fluid communication. A valve member is mounted in the housing for forward and rearward sliding movement and has a first portion and a second portion. The first portion has an upwardly facing surface having a radius of curvature that closely approximates a radius of curvature of an outer diameter of the gas tube, and the second portion has threads. A nut is carried by the housing for rotational movement and has threads mating with the threads on the second portion of the valve. Rotating the nut in a first direction translates the valve member forwardly and rotating the nut in a second opposite direction translates the valve member rearwardly. The axial position of the first portion of the valve member controls the amount of gas passing from the first passageway to the gas tube by completely opening, partially opening, or completely closing the first passageway.
1. An adjustable gas block for a firearm, comprising:
a housing adapted to be attached to a barrel of the firearm,
the housing having a first passageway adapted to be aligned with a gas port in a barrel of the firearm and a second passageway adapted to receive a gas tube of the firearm, such that a bore of the barrel, the gas port of the barrel, the first passageway, and the gas tube are in fluid communication,
a valve member mounted in the housing for forward and rearward sliding movement and having a first portion and a second portion, the first portion having an upwardly facing surface having a radius of curvature that closely approximates a radius of curvature of an outer diameter of the gas tube, the second portion having threads, and
a nut mounted to the housing for rotational movement and having threads mating with the threads on the second portion of the valve member,
whereby rotating the nut in a first direction translates the valve member forwardly and rotating the nut in a second opposite direction translates the valve member rearwardly, the axial position of the first portion of the valve member controlling the amount of gas passing from the first passageway to the gas tube by completely opening, partially opening, or completely closing the first passageway.
2. The adjustable gas block of claim 1 , further including a resilient detent carried by the housing that cooperates with the nut to provide positive engagement of the nut at a plurality of rotational positions of the nut.
3. The adjustable gas block of claim 1 , wherein:
the nut includes a forward portion, a rearward portion, and a central portion, the central portion having an outer diameter less than an outer diameter of the rearward portion, and
the housing has a recess forward of the first passageway, the recess having a forward shoulder and a rearward shoulder,
the recess receiving the rearward portion of the nut, a rearward surface of the rearward portion of the nut abutting the rearward shoulder of the recess to prevent rearward translation of the nut, a forward surface of the rearward portion of the nut abutting the forward shoulder to prevent forward translation of the nut.
4. The adjustable gas block of claim 3 , wherein the forward and rearward portions of the nut each include a plurality of longitudinally extending grooves circumferentially spaced therearound.
5. The adjustable gas block of claim 1 , wherein an axis of rotation of the nut is positioned below a longitudinal axis of the gas tube.
6. The adjustable gas block of claim 5 , wherein the axis of rotation of the nut and the longitudinal axis of the gas tube are spaced apart by an amount less than one half of the sum of the outer diameter of the gas tube and an outer diameter of the forward portion of the valve member.
7. A firearm, comprising:
an action,
a barrel having a bore and a gas port,
a gas tube for receiving gas from the bore via the gas port and directing the gas to the action to cycle the action,
an adjustable gas block having a housing attachable to the barrel,
the housing having a first passageway aligned with the gas port and a second passageway receiving the gas tube, such that the bore, the gas port, the first passageway, and the gas tube are in fluid communication,
a valve member mounted in the housing for forward and rearward sliding movement and having a first portion and a second portion, the first portion having an upwardly facing surface having a radius of curvature that closely approximates a radius of curvature of an outer diameter of the gas tube, the second portion having threads, and
a nut mounted to the upper housing for rotational movement and having threads mating with the threads on the second portion of the valve member,
whereby rotating the nut in a first direction translates the valve member forwardly and rotating the nut in a second opposite direction translates the valve member rearwardly, the axial position of the first portion of the valve member controlling the amount of gas passing from the first passageway to the gas tube by completely opening, partially opening, or completely closing the first passageway.
8. The firearm of claim 7 , further including a resilient detent carried by the housing that cooperates with the nut to provide positive engagement of the nut at a plurality of rotational positions of the nut.
9. The firearm of claim 7 , wherein:
the nut includes a forward portion, a rearward portion, and a central portion, the central portion having an outer diameter less than an outer diameter of the rearward portion, and
the housing has a recess forward of the first passageway, the recess having a forward shoulder and a rearward shoulder,
the recess receiving the rearward portion of the nut, a rearward surface of the rearward portion of the nut abutting the rearward shoulder of the recess to prevent rearward translation of the nut, a forward surface of the rearward portion of the nut abutting the forward shoulder to prevent forward translation of the nut.
10. The firearm of claim 9 , wherein the forward and rearward portions of the nut each include a plurality of longitudinally extending grooves circumferentially spaced therearound.
11. The firearm of claim 7 , wherein an axis of rotation of the nut is positioned below a longitudinal axis of the gas tube.
12. The firearm of claim 11 , wherein the axis of rotation of the nut and the longitudinal axis of the gas tube are spaced apart by an amount less than one half of the sum of the outer diameter of the gas tube and an outer diameter of the forward portion of the valve member.
13. An adjustable gas block for a firearm, comprising:
a housing adapted to be attached to a barrel of the firearm,
the housing having a first passageway adapted to be aligned with a gas port in a barrel of the firearm and a second passageway adapted to receive a gas tube of the firearm, such that a bore of the barrel, the gas port of the barrel, the first passageway, and the gas tube are in fluid communication,
a valve member mounted in the housing for forward and rearward sliding movement and having a first portion and a second portion, the second portion having threads, and
a nut mounted to the housing for rotational movement and having threads mating with the threads on the second portion of the valve member,
whereby rotating the nut in a first direction translates the valve member forwardly and rotating the nut in a second opposite direction translates the valve member rearwardly, the axial position of the first portion of the valve member controlling the amount of gas passing from the first passageway to the gas tube by completely opening, partially opening, or completely closing the first passageway,
wherein the first portion of the valve member is configured such that an axis of rotation of the nut and a longitudinal axis of the gas tube are spaced apart by an amount less than one half of the sum of an outer diameter of the gas tube and an outer diameter of the forward portion of the valve member.
14. A firearm, comprising:
an action,
a barrel having a bore and a gas port,
a gas tube for receiving gas from the bore via the gas port and directing the gas to the action to cycle the action,
an adjustable gas block having a housing attachable to the barrel,
the housing having a first passageway aligned with the gas port and a second passageway receiving the gas tube, such that the bore, the gas port, the first passageway, and the gas tube are in fluid communication,
a valve member mounted in the housing for forward and rearward sliding movement and having a first portion and a second portion, the second portion having threads, and
a nut mounted to the housing for rotational movement and having threads mating with the threads on the second portion of the valve member,
whereby rotating the nut in a first direction translates the valve member forwardly and rotating the nut in a second opposite direction translates the valve member rearwardly, the axial position of the first portion of the valve member controlling the amount of gas passing from the first passageway to the gas tube by completely opening, partially opening, or completely closing the first passageway,
wherein the first portion of the valve member is configured such that an axis of rotation of the nut and a longitudinal axis of the gas tube are spaced apart by an amount less than one half of the sum of an outer diameter of the gas tube and an outer diameter of the second portion of the valve member.