Get one of the 4350s Accurate, Hodgdon or IMR and with 120 gr bullets work up to max of 46 grs and with 140s work up to 44 grs if using Hodgdon and 45 grs with the others and you should find what you are looking for.
With an 18" barrel you should concentrate on faster burning powders than 4831. 4350 should be a good spot to start varget would be worth a try. You can look at your data and pick the faster burn rates and try them. Slower burn rates and short barrels don't go together well.
Good luck and shoot straight
Bob
Faster burning powders will make no difference in a shorter barrel. Whatever powder is fastest in a 24" will be the fastest in an 18".
What are your thoughts on slower burn rate powders not burning completely prior to the bullet exiting the bbl?
Shoot straight
Bob
"The common notion that faster powders will work better in shorter rifle barrels is wrong, primarily because all the powder that's going to turn into gas does so inside the first few inches of a barrel. (Muzzle flash is not unburned powder kernels flying out of the muzzle, but hot powder gas re-igniting when it hits the oxygen of the atmosphere.)
The same powders that get the highest velocity in longer rifle barrels get the highest velocity in short barrels too. If you want some proof, look at various loading manuals that list the same cartridge data in both rifles and handguns. You'll find the same powders getting the top velocities in both, or at least powders in the same burning rate range--slow
for the cartridge and bullet.
The least amount of velocity loss in a shorter barrel is typically with heavier bullets and slow powders." ...John Barsness
Thanks for the response. I had an experience with a 270 win with a carbine length barrel that shot faster with 4895 than with 4831 which has been the opposite of my experience with a 24 accumark that I own.
I have since sold the carbine length rifle and kept the accumark. But the carbine length rifle shot significantly better with 4895 than with my old standby load of H4831. I had thought it associated with barrel length but perhaps it was only the powder rifle combo.
All in all I believe I would still try a faster burning powder in the swede. What are your thoughts? I owned a 270 win mountain rifle that really liked I4350 better than 4831 as well.
Good luck and shoot straight all
Bob