I had a 18" IIRC 45acp barrel that was a tack driver. The same load that I shot in my 1911 gained 250fps or more in the longer tube.
Got to playing around with Rem 180?gr HP jacketed and Blue Dot. Won't list the load, but the charge was compressed. velocity was aver 1,600fps with no signs of pressure at all, no case expansion beyond normal, primers were still round on the edges.
Was going to try the Lee 300gr RFN but never got around to making a nose sizer so the bullet would enter the rifling, then sold the barrel.