What you're looking for is about impossible to find, VERY occasionally you might run across one on Fleabay, but you'd literally have to check on a daily basis, cause it wouldn't last long unless it was priced out of this world.
A 1200/1300 pump barrel is much easier to find in slug persuasion, and is identical to a 1400/1500 barrel except the 1400/1500 has a gas port drilled into the barrel at the barrel lug. You can actually use a 1200/1300 barrel on a 1400/1500 and it will work untouched, but as a single shot cause without the gas port in barrel the guns action can't function.
Check with any competent gunsmith in your area, he should be aware of it and should be able to drill the correct size gas port in a 1200/1300 barrel for you if you find one.
