Daniel, you'll get best results using high velocity ammo rated 1300fps or higher. The SDS Bullpup has trouble cycling lower powered rounds. Video here >>> youtube.com/watch?v=yWubkcizxNA .....Have a great day!

Daniel, for self defense the following Buckshot and Slug loads are recommended : (inside of the Home): budsgunshop.com/product_info.php/products_id/411559297/rio+royal+buck+12+ga+2-34+#4-buck+27+pellet+5rd+box ------------------ (Outside of the home) : budsgunshop.com/product_info.php/products_id/713073446/nobelsport+12ga+275+00-buck+10rd+box (Outside the home farther distance) : budsgunshop.com/product_info.php/products_id/15600/federal+vital+shok+12+ga+2+34+1+oz+lead+rifle+slug+5rd+box

This has a 3 inch chamber so 2-3/4 inch and 3 inch shells will work in this This will also shoot scatter, buck or slugs. When using 2-3/4 inch shells I'd use standard to high velocity rounds to make the bolt completely cycles for reliability. Hope this helps.