first barrel length

for a normal sporting rifle with half stock I would allways prefer 60cm or 24 inch

a full stock stutzen with 50cm or 20 inch is maybe the best

for other rounds? the only factory cartridge today working in an unchanged magazine is the PRVI 8x56R Mannlicher I believe. 9,3x53R Finnish and 8,2x53R ( a 7,62x54R with an 8mm S bullet)are semi obsolet today made by Sako or Lapua from time to time. 8,2x53R goes in the magazin and 9,3x53R needs only a little bit of work.
the russian 9,3x53R which is a copy of the 9,3 finnish is not to buy outside of mother russia. 8x50R Mannlicher works without any hassle but is complete obsolete if you cant get the .315 India ammo.
this are two cartridges I looking for some time to get only a collector sample without success.

there is an 7x53R Finnish iirc, a 7,62x53R case necked down for the 7mm caliber and in the 7x57 mauser class. the finnish 6,3x53R is more a small game round but the russian 6,5x54R is similar to the 6,5x55.

of course there are cases like 45/70 but they need a rebuild of the original magazine.
if you looking for something very special I need a a new chamber reamer for the 10,75x52R Springers in the future. the basic case for this obsolete round is 8x56R PRVI. it fire a 350 grains bullet at 620 m/sec but will handle 400 grains bullets for the 404 Jef. also.