How can you make a Remington 1187 Sportsman shoot low brass ammo?

To make a Remington 1187 Sportsman shoot low brass ammo reliably, you will need to increase the spring pressure in the magazine tube. This is done by replacing the factory mainspring with a heavier one. Wolff Gunsprings offers several different spring weights for the 1187, and you may need to experiment to find the one that works best for your gun with low brass ammo.

In addition to replacing the mainspring, you may also need to adjust the gas system. The 1187 Sportsman has a two-position gas system, and you will want to ensure it's set to the "light load" setting for low brass ammo. If your gun still doesn't cycle low brass ammo reliably after these adjustments, you may need to have the gunsmith look at it to ensure there are no other issues preventing it from functioning correctly.