Noveske Rifleworks has released its switchblock. The information on the Noveske website is shown below, and should answer most questions.

http://www.noveskerifleworks.com/switchblock/




With the increased and often mandatory use of sound suppressors in today's Military and Law Enforcement, certain issues have arisen which require attention regarding the M16/M4 family of weapons. For over two years we have been working on a simple user friendly solution to mitigate the side effects of sound suppressor use on this weapon platform. The result is the Noveske Switchblock®. It is a light weight, simple and durable gas block designed to regulate the increased flow of gas caused by use of a sound suppressor.

COMMON EFFECTS OF SOUND SUPPRESSOR USE
The installation of a sound suppressor causes a few problems of varying importance on the M16/M4 family of weapons.
--Increased bolt speed/premature bolt unlock
--Increased chamber and receiver area fouling
--Increased cyclic rate on Auto
--Increased wear on weapon components
--Increased recoil due to increased bolt carrier group/buffer impact on the rear of the receiver extension
--Increased propellant gasses directed to to the shooter's face
--Premature weapon failure during suppressed use

Unsuppressed Cycle of Operation:
The expansion of the cartridge case neck against the chamber wall seals the propellant gases from leaking around the case. The propellant gasses expand, forcing the projectile through the bore, past the gas port and out the muzzle. The gasses passing through the barrel's gas port, travel rearward through the gas tube and expand in the bolt carrier group, ultimately resulting in the rearward movement of the carrier and the extraction of the spent cartridge case. During the weapon's cycle of operation in unsuppressed use, the bolt unlocks and extracts the spent cartridge case once the propellant gas pressure has been reduced to a level that allows for minimal carbon fouling on the chamber and receiver walls.

Suppressed Cycle of Operation:
With a sound suppressor in place, once the round exits the muzzle, the sound suppressor begins to collect the propellant gasses. Then the sound suppressor holds and delays the exit of the propellant gasses through the front of the sound suppressor. This action also delays the normal reduction of propellant gas pressures throughout the bore and chamber. Simultaneously, the gasses passing through the barrel's gas port, travel through the gas tube at a higher volume and expand in the bolt carrier group sooner than the weapon is designed to handle. The bolt carrier begins it's rearward movement prematurely which also extracts the spent cartridge case before the propellant gas pressure has been reduced to the safe level. Once the spent cartridge case is pulled out of the neck area of the chamber, the carbon rich high pressure propellant gasses escape to the rear around the case and coat the case and chamber walls with carbon. The carbon continues to move to the rear into the receiver area, continuing to coat the receiver walls, bolt carrier group, and the unfired cartridges loaded in the magazine with carbon. Continued use in this manor results in a layer of carbon that will cause a malfunction of the weapon by means of a stuck cartridge case in the chamber or a failure to feed or eject because of increased friction between the bolt carrier and the receiver walls. Lastly, the shooter experiences a blast of pungent propellant gasses directed at his/her face causing difficulty breathing and seeing.

RESULT--Premature weapon failure during suppressed use.


SOLUTION

With the use of the Switchblock and a sound suppressor, these problems are all addressed and corrected. The barrels gas port diameter is effectively reduced to a level that restricts the volume and pressure of propellant gasses flowing into the gas tube to a level that allows for the propellant gas pressure in the bore and chamber to be reduced to a safe level prior to spent cartridge case extraction. The spent cartridge casings are visibly cleaner, the bolt carrier and receiver are coated with carbon at a slower rate, (compared round for round with an unregulated suppressed weapon), and the chamber remains cleaner. Unfired cartridges in the magazine remain cleaner prior to their entry into the chamber.

Benefits include:
--Reduced Recoil
--Normal cyclic rate on Auto
--Faster target acquisition/reacquisition
--Increased round count through the weapon between cleanings
--Increased weapon performance with sound suppressor use
--Reduced wear on weapon components
--Reduced propellant gas exposure to the shooter's face

RESULT-The weapon stays in the fight longer with more rounds on target.

CONSTRUCTION:

The Switchblock is made entirely of 17-4 ph Stainless. It is extremely heat and corrosion resistant.