So I'm trying to develop a reference table for buffer weights, bcg weight and gas system length. I have quickload to get pressure at the gas port with each gas system, max chamber pressure and case capacity.
It will all be calculated with max loads for each caliber with a .093" gas port. I will be calculating gas volumes, bore volumes and the volume of the gas system.
For reference of a properly gassed system I am using a .093" gas port, carbine buffer, standard weight bcg rifle length gas system 223 with a max charge of h4895 (25.8 gr)and a 55 gr bullet making 55000 psi chamber pressure, 3157 fps and 15875 psi at the gas port. A total volume of gas created at 93.41% of propellant burnt is 1561cc or 95.26 cubic inches of gas. (All smokeless powder makes 1 liter of gas per gram of powder burnt. Doesnt matter what powder it is as all double base smokeless powders are the same base and create the same amount of gas. It's the retardant coating on the powder that dictates burn rate.) Burn rate dictates how much powder will be burnt in the duration of the projectile traveling down the barrel. That's why the 93.41% is there. Bullet weights will also change the amount of propellant burnt
So my question is for you fine folks is, is there anything else I should consider in my calculations other than case capacity, max pressure, gas system length, gas port diameter, gas volume, pressure at gas port, pressure at muzzle, barrel length, bullet weight charge weight, bcg weight and gas system volume assuming that a standard spring rate buffer spring is being used.
So far in my preliminary calculations I have noticed the 204 ruger makes 20626 psi at the port and the 30 Remington AR makes 11865 psi with the 7.62x39 making only 9894 psi which is only 888 psi more than a 223 has at the muzzle on a 20 inch barrel.
I understand that every rifle is different and I just want to create a base line people can reference for new builds on non mainstream cartridges like the 30Rem Ar and others.
For those who have built a 7.62x39 or 30 rem ar or 450 bushmaster where is the gas port? Rifle, mid, carbine or pistol. My numbers are saying a 450 BM should have a pistol length gas system. Is this right?
It will all be calculated with max loads for each caliber with a .093" gas port. I will be calculating gas volumes, bore volumes and the volume of the gas system.
For reference of a properly gassed system I am using a .093" gas port, carbine buffer, standard weight bcg rifle length gas system 223 with a max charge of h4895 (25.8 gr)and a 55 gr bullet making 55000 psi chamber pressure, 3157 fps and 15875 psi at the gas port. A total volume of gas created at 93.41% of propellant burnt is 1561cc or 95.26 cubic inches of gas. (All smokeless powder makes 1 liter of gas per gram of powder burnt. Doesnt matter what powder it is as all double base smokeless powders are the same base and create the same amount of gas. It's the retardant coating on the powder that dictates burn rate.) Burn rate dictates how much powder will be burnt in the duration of the projectile traveling down the barrel. That's why the 93.41% is there. Bullet weights will also change the amount of propellant burnt
So my question is for you fine folks is, is there anything else I should consider in my calculations other than case capacity, max pressure, gas system length, gas port diameter, gas volume, pressure at gas port, pressure at muzzle, barrel length, bullet weight charge weight, bcg weight and gas system volume assuming that a standard spring rate buffer spring is being used.
So far in my preliminary calculations I have noticed the 204 ruger makes 20626 psi at the port and the 30 Remington AR makes 11865 psi with the 7.62x39 making only 9894 psi which is only 888 psi more than a 223 has at the muzzle on a 20 inch barrel.
I understand that every rifle is different and I just want to create a base line people can reference for new builds on non mainstream cartridges like the 30Rem Ar and others.
For those who have built a 7.62x39 or 30 rem ar or 450 bushmaster where is the gas port? Rifle, mid, carbine or pistol. My numbers are saying a 450 BM should have a pistol length gas system. Is this right?
