You might find that it actually slows it down a bit. I was shocked when I built a 260 Rem and kept the barrel at 27". All my loads chrono'd over 150 fps slower than they should have. Later my wife wanted the barrel cut down so I cut and crowned it to 24". Now the velocity is up to normal.

Same thing happened when I built a 280 Rem and left the barrel at 26". I suspected it was that the publishedloads were worked up in 24" barrels and chamber pressure was dropping off before the bullet left the longer barrel. I contacted a couple of powder manufacturers and they concurred.

Instead of shortening that barrel, this timeI took Alliant's advice &experimented with powders that were slower than published powders. IMR 7828 and RL 25are working well with 120 & 140 gr bullets in that gun, with velocities a little faster than a normal 24" in that cartridge.
good luck