Conversely, the more spherical firing pin nose tends to more fully close off the firing pin hole in the breech face at full impact and during peak breech pressure
. Whereas the oval or more pointed firing pin nose would tend to allow the primer wall to extrude more along the firing pin nose and along the inner wall of the firing pin hole in the breech face.
Built on a Howa or Remington 700 centerfire action, the BP Xpress Hunter is designed for long-range muzzleloading performance and engineered to withstand a breech pressure
of 125,000 psi.
The 213-grain, roundnose, jacketed bullet had a velocity of 1,968 fps and a breech pressure
of 37,000 psi.
It can be said that the history of progress in powders from black powder days has been a story of development of slower and slower gunpowders, producing higher and higher velocities within the standard limitations of case capacity, rifle strength, breech pressure
, and recoil.
The approach to this point in a series of progressively heavier and heavier charges can be observed on a chronograph, when each heavier load produces a smaller increment of velocity, until a point is reached at which another half-grain of propellant delivers little or no more muzzle velocity but a possibly-disastrous increase in breech pressure
The 1971-72 edition lists 82 grains max for 2,670 fps and 52,000 CUP breech pressure
, but the 1975-76 edition shows a top charge of only 78 grains, for 2,620 fps and 52,700 CUP!
Long before the breechblock has started rearward from the recoil the bullet has left the 4-1/2-inch barrel and breech pressure
has dropped to zero.
The 1895 was Winchester's response to the appearance of smokeless powders and cartridges with pointed bullets and high breech pressures
. It was initially offered in.30-40 Krag, .38-72-275 and.40-72-330.