I have in hand, two 'factory loaded' OLD rolled crimp cartridges:
1/ 20ga., RED HEAD-RELIANCE, length is 1 5/16" base to roll
2/ 16ga., WESTERN-XPERT, length is 1 5/16" base to roll

I take it these would be about 2 1/2" when fired; so they are 2 1/2" cartridges!
I can check the 20ga., but don't have a 16ga. gun at the moment.

Just got my RST 12 Ga 2 1/2" Maxilites with 1 oz of #9's for my 1891 GH. If I'm measuring right, base to crimp is 2 1/8". Fired, it should be 2 1/2". Can't wait to light them off in my "new" Damascus barrels brought back to life by Buck Hamlin.