Recently purchased a Glock 20sf, never shot a semi auto before. In fact this is my second and final gun purchase. My first is my Ruger GP100357. I am wanting to purchase a conversion barrel to shoot the cheaper 40sw, is this a drop in process or do i have to modify or alter anything in my gun? I will be trying this gun out in the range this monday with Magtech 180 grain 10mm, got it for $17.99 at Sportmanswarehouse in Milpitas CA. Thanks for the future respones.