Notice it specifies this is a 3 Dram Equivalent load, which is what 82 grains of Black Powder would be. You use black powder. 6. Bullet exit time 8. Maximum Pressure ( in PSI Unless Noted) Recommended By SAAMI: T he S porting A rms and A mmunition M anufacturers ' I nstitute: H andgun: PSI: R ifle: PSI: R ifle (Cont.) More pressure with smokeless powder so just lightening and load is still unsafe. The pressure will then remain constant until all the liquid is gone and this is why a CO2 powered gun will not lose velocity until all the liquid is gone to the point it is running solely on gas. Seating the bullet deeper to allow more travel before it takes the rifling, as in these next two illustrations, permits the bullet to get a … I have a handsome custom rifle on the Krag action built by Griffin & Howe during the 1930s, and it is chambered to .22 Hornet, which is commonly loaded to 47,000 c.u.p. Rifles can encounter pressure problems for a wide number of reasons. You get a different pressure curve a lot. Reloaders Corner: Pressure Curves for Semi-Automatic and Bolt-Action Rifles Pressure remains safe throughout the powder burning period [Fig. Now that's that's that's the beauty of. 30], and the velocity obtained—3,500 feet per second (fps)—is "normal" for this load in this rifle. pressure curve rise times are independent of the pressure levels.” Smokeless powders are generally progressive burning powders, meaning that as the pressure increases the burn rate increases. Gravity of 386 in/sec^2 Note: Not only is the muzzle exit angle changing in time, but the muzzle is also moving in the vertical direction while the bullet is traveling down the barrel. Excessive fouling, extremely hot environmental conditions, uniformity problems with components, lubrication finding its way into your chamber, or even a surprise rain storm can all lead to a condition which will produce unsafe pressures. The impulse is the integral or the area under that curve. The graph represents the pressure curves of two charges of powder used in a 12 gauge shotgun to accelerate 1 1/8 ounces of shot to 1200 fps. Most rifle cartridges have a high load density with the appropriate powders. Magnum pistol cartridges reverse this power/accuracy tradeoff by using lower-density, slower-burning powders that give high load density and a broad pressure curve. In the U.S., voluntary pressure standards for rifle cartridges are set by SAAMI, a member of ANSI.Most other countries in the world follow the standards of Europe's CIP (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives or Permanent International Commission for the Proof of Small-arms, sometimes referred to as the International Proof Commission). Maximum recommended chamber pressure for the Model 1898 Krag in .30-40 caliber is 40,000 c.u.p. That okay alright black powder good old … Or black powder substitute. Pressure curve scaled for the correct Muzzle Velocity 7. So the ... rifle and are loaded to attain the same velocity (key point), the area This maybe not so messy okay. The force would be the gas pressure multiplied by the area of the piston face, so the impulse or momentum transfer is proportional to the area under the above gas pressure curve. The downside is the increased recoil and muzzle blast from the high powder mass, and high muzzle pressure.