Here is a link that a gentleman ran in Hank's Forum conducting a test with recorded results. He cut off a 25-inch barrel 1 inch at a time till it was 17 inches firing multiple shots with a chronograph. The results were interesting...
I failed to remove my ramrod from my Savage 10ml2 before shooting. 65 grains of IMR4198, orange mmp sabot and a .458 300 gr Remington JHP. Recoil was very harsh. It was my first shot and thought I did not shoulder rifle correctly. New powder load down the barrel, started sabot and bullet and...
I have burned thru almost 3 lbs of IMR4198 in my savage with a vent liner. Never had any issues as long as I kept an eye on the flame channel diameter. .035 is as big as I will let it get then I change to new one. Have fun.