WHY IS SEATING DEPTH IMPORTANT?

Why is seating depth important when it comes to the size of your groups??

Seating depth determines how far a bullet has to "jump" through the freebore of your chamber before engaging the lands/rifling. 

Gavin from Ultimate Reloader was kind enough to allow us to use this beautiful sectioned barrel to illustrate how a cartridge interacts with a modern chamber. 

The further your bullet jumps, the higher it's velocity is when it engages the lands and begins rotating. In order to maintain a consistent pressure vs. time curve propelling the bullet down the barrel, and ensure the bullet's concentricity within the bore and grooves of your barrel, we must create a consistent seating depth that holds the bullet at an optimal distance from the lands. The only way to know what this optimal distance is for YOUR system, is to test it. 

The Type 1 Designs Seating Depth Tool provides you the ability to quickly and easily adjust the seating depth of loaded cartridges to perform this test, and "fine tune" those loads specifically to your rifle's optimal jump distance. 

Gavin explains this beautifully in his video "The Perfect Seat - How to Get Consistent Seating Depth Every Time!" which you can find on YouTube along with other in-depth explanations on seating depth from experts and high level precision competitors. I highly recommend watching their content if you care to dive down the rabbit hole...