Our products are engineered and manufactured with tighter tolerances than their factory counterparts. These improved tolerances are what enable us to pull additional performance and accuracy out of our barrels and improved cyclic rate out of our slides.
However, there is no such thing as a free lunch. By tightening up tolerances, you often sacrifice a bit of "forgiveness". Factory pistols are designed with an intentional amount of forgiveness which allows people to run a wide variety of ammunition in a plethora of environmental conditions right out of the box. The cost of this forgiveness, however, is accuracy and consistency.
Performance can be improved by tightening things up, but it often means that some break-in will be required to get all of the friction surfaces worn in and playing nicely together. Break-in is typically completed after a few magazines worth of live fire.
If you're experiencing a bit of sticking or "hanging-up" with your brand new slide, barrel, or both, try giving the back of the slide a little "love tap" to make sure it goes into battery. If it rides forward and goes into battery with a tap, then we recommend putting a few magazines through it and see how it feels afterward. That sticking should be gone and your parts should be mated up perfectly, providing 100% function and reliability.
It's important to note that "hand-racking" alone is often insufficient to properly break in new components. The forces exerted on the pistol during live fire are significantly stronger than anything that can be imparted during hand-racking. They say a picture is worth a thousand words, but we prefer the saying: "A mag of live fire is worth a thousand hand-racks."