Testing rifle ammunition in the short barrel [?]


for what purpose, in the development of a new rifle/carbine, or rather a barrel / cartridge assembly, in addition to tests of barrels of standard length, very short barrels were also made [for the same cartridge]?

For example: barrel length ~ 12cm = end of barrel in bullet positon (for ex. size of cartridge 12,7x99).

Maybe for the primer tests? Shooting to white paper and pollution assessment?
Or as on photo below - .22 flame size measurement, strenght of the primer.
But for this two types of test probably useds only a cut / shortened cases [not full size chamber].




According to Textbook of Small Arms of 1929, page 269 the British used an only 3 inch long .303 barrel (quote: the nose of the bullet sticks out of the barrel) to test for “set up” of the bullet. That is the expansion needed to fill out the grooves of the barrel.
Your device could be for a similar purpose.

Many thanks. It looks like it’s about forcing cone / origin of rifling.

exactly !