m14medic.ca
Expried Business Member
- Location
- Regina SK Canada
OP, sorry for the derailment of this thread...... I guess I opened a couple different cans of worms!
The big problem with Varget and the other new “super performance” powders is that they maintain max pressure in the barrel for a longer time period. This increases the port pressure, which can substantially increase the pressure in the gas system before the piston passes by the vent on the bottom of the gas cylinder or the bullet uncorks.
Conventional powders like 4895 tend to have a quick initial peak pressure but once the bullet is 10-15% of the way down the barrel pressure stops building and starts to subside. In a rifle that sees a 50K psi peak at the chamber will only be 10-12K psi at the port.
Varget and the other new “super duper” powders were designed to hold that peak pressure for much longer. Different coatings, burn rates etc. mean that the same rifle with 50Kpsi of peak pressure will still be at peak pressure for inches more than with conventional powders. This means that it is possible to see port pressures at 20K psi+. This equates to a much more vigorous reaction from the gas piston than the system was designed for.
There are several options/tweaks that can be done to an M-14’s gas system to mitigate these port pressures. Grooved pistons, adjustable gas plugs, drilling a small vent hole in a gas plug to name a few.
Using Varget is possible, but one must be cognizant of the hazards!
John
The big problem with Varget and the other new “super performance” powders is that they maintain max pressure in the barrel for a longer time period. This increases the port pressure, which can substantially increase the pressure in the gas system before the piston passes by the vent on the bottom of the gas cylinder or the bullet uncorks.
Conventional powders like 4895 tend to have a quick initial peak pressure but once the bullet is 10-15% of the way down the barrel pressure stops building and starts to subside. In a rifle that sees a 50K psi peak at the chamber will only be 10-12K psi at the port.
Varget and the other new “super duper” powders were designed to hold that peak pressure for much longer. Different coatings, burn rates etc. mean that the same rifle with 50Kpsi of peak pressure will still be at peak pressure for inches more than with conventional powders. This means that it is possible to see port pressures at 20K psi+. This equates to a much more vigorous reaction from the gas piston than the system was designed for.
There are several options/tweaks that can be done to an M-14’s gas system to mitigate these port pressures. Grooved pistons, adjustable gas plugs, drilling a small vent hole in a gas plug to name a few.
Using Varget is possible, but one must be cognizant of the hazards!
John




















































