Our load data is constructed in a very close and controlled environment. All of our “test” barrels are at the minimum specification. Most commercially produced rifle barrels tend to be a tiny bit larger in the bore, thus reducing pressure and velocity. This is the category where most of the off the shelf firearms fall into.
Even though your velocity doesn’t match ours in the book, caution still needs to be adhered to. Because of the controlled test environment and state of the art pressure testing equipment, the book maximum load is just that. DO NOT EXCEED the maximum load. Always start with the minimum load and work your way up to find the right load for your gun.