Thread: Is it Pressure or Powder Capacity?

Originally Posted by veitnamcam

No but search the internet for even one case of a 22-243 barrel lasting 5-10 thousand rounds accurately.

Anecdotally we know that chamberings running the same pressure the smallest bore size will wear first, which makes perfect sense as for the same volume and the same preasure to get threw a smaller hole takes more time.
Another way to look at it is for a same amount of powder/gas to get threw a smaller hole then the surface of that hole is subjected to more contact/abrasion/heat in order to flow the same amount.

Maybe think of it in terms of total volume of barrel + cartridge case. By the time the bullet is about to exit the muzzle it is at least evenly distributed, probably pressure slightly higher in the case itself. Come the point when the bullet leaves the muzzle, all that pressure now gets vented forwards unhindered, except for barrel resistance. In the case of a magnum size cartridge behind a .22 barrel, that will be quite a rush of fast gases hitting the throat area of the barrel and they will be at a relatively high pressure for longer due to the small diameter (=more resistance to gas flow) of the barrel.