I am offering a chronograph service using the best chronograph on the market, the Lab Radar. This uses radar waves to measure the true speed of the bullet. It can measure at multiple distances up to about 50 yards. This will not impact your gun or bullet's trajectory in any way.
The rates will vary depending on where you want to shoot, but I am charging $25 for public ranges near DFW airport. I will meet you at the range, work with you for an hour and provide velocity for as many guns as you would like. I can point you in the direction of ballistic calculator that will give you specific data for various distances. I am open to groups and will travel as needed. So if your whole deer lease or buddies want there true velocity, message me and we can figure something out.