Adjustable Volume Piston System

Abstract

An adjustable volume gas piston system for a pneumatic reloading firearm includes a gas block having an anchoring portion for anchoring along the barrel. The gas block also includes a chamber portion in pneumatic connection with the barrel. The chamber portion has one end pointing toward the muzzle and another end pointing away from the muzzle. A plug having a bore is affixed to the chamber portion at the forward end. The second end has an opening to allow travel of a gas pin but retains a gas pin head in the chamber portion, biasing it toward the first end. Upon firing the firearm, the volume of the bore causes a pressure delay on the gas pin head, thereby delaying the timing of pneumatic reloading.

What is claimed is: 
     
         1 . An adjustable volume gas piston system for a pneumatic reloading firearm having a barrel with a muzzle, comprising:
 a gas block having an anchoring portion for anchoring along the barrel;   a chamber portion in pneumatic connection with the barrel, the chamber portion having a first end proximal the muzzle and a second end distal from the muzzle;   a removable plug having a bore, the plug affixed to the chamber portion at the first end; and   the second end having an opening to receive a gas pin, wherein the gas pin comprises a gas pin head retained in the chamber portion and biased toward the first end, and wherein upon firing the firearm, the volume of the bore causes a pressure delay on the gas pin head, thereby delaying the timing of pneumatic reloading.   
     
     
         2 . The gas piston system of  claim 1  wherein the plug moves relative to the chamber portion. 
     
     
         3 . The gas piston system of  claim 1  wherein the plug comprises a threaded member that rotatably engages the chamber portion. 
     
     
         4 . The gas piston system of  claim 1  wherein adjusting the position of the plug changes the volume inside the chamber portion. 
     
     
         5 . The gas piston system of  claim 1  wherein the plug comprises a biased stop mechanism that preserves the volume of the chamber portion at a predetermined volume. 
     
     
         6 . The gas piston system of  claim 5  wherein the biased stop mechanism comprises a bearing in a biased position on the plug and a complimentary seat on the gas block. 
     
     
         7 . The gas piston system of  claim 6  wherein the gas block comprises multiple seats capable of anchoring the plug in multiple positions. 
     
     
         8 . The gas piston system of  claim 1  wherein prior to firing the gas pin head is biased to a position abutting the plug. 
     
     
         9 . The gas piston system of  claim 1  wherein the gas pin head comprises a concave surface facing the bore. 
     
     
         10 . The gas piston system of  claim 1  wherein the gas pin head comprises circumferential channels that introduce turbulence into gases passing between the gas pin head and the chamber portion. 
     
     
         11 . The gas piston system of  claim 1  wherein the second end comprises a cut-out that allows gasses passing between the gas pin head and the chamber portion to exit through the second end. 
     
     
         12 . The gas piston system of  claim 1  wherein the chamber portion comprises an exhaust port obscured by the gas piston head in a biased position. 
     
     
         13 . The gas piston system of  claim 12  wherein the exhaust port is obscured by the gas pin head prior to firing the firearm and is cleared by the gas pin head when the gas pin head is pushed toward the second end. 
     
     
         14 . The gas piston system of  claim 1  further comprising an impinging screw between the barrel and the chamber portion for closing the pneumatic connection. 
     
     
         15 . An adjustable volume gas block for a firearm having a barrel and a gas pin, comprising:
 a plug having a bore;   the plug inserted into the gas block bringing the bore in pneumatic communication with the barrel;   the gas pin biased against the bore forming an enclosed chamber; and   wherein when the firearm is fired, gas enters the enclosed chamber, forcing the gas pin away from the bore; and   wherein as the gas pin moves away from the bore a port is exposed allowing the gas to exit the gas block.   
     
     
         16 . The gas block of  claim 15  wherein the plug comprises a threaded member for rotatably engaging the chamber portion. 
     
     
         17 . The gas block of  claim 15  wherein the plug comprises a biased stop mechanism for preserving the volume of the chamber portion at a predetermined volume. 
     
     
         18 . The gas block of  claim 17  wherein the biased stop mechanism comprises a bearing on the plug and a seat on the gas block. 
     
     
         19 . The gas block of  claim 18  wherein the gas block comprises multiple seats for anchoring the plug in multiple positions. 
     
     
         20 . A method of adjusting the timing of an automatic reloading firearm having a gas pin and a barrel, comprising the steps of:
 providing a gas block having a chamber;   installing a gas block on the barrel;   providing a pneumatic communication in the gas block between the chamber and the barrel;   providing a plug having a bore;   inserting the plug into the chamber;   inserting the gas pin into the chamber opposite the plug; and   firing the firearm, thereby causing a delay in the automatic reloading action of the gas pin.