Tell you how I establish burning rate. I have a Handi that has been rechambered to .357 Max, but a .357 mag would do. The rifle is good to about 55k psi. I loaded a batch of .357 Mag ammo using AA 9 data, and chronied it. Velocity I got was a close match to book velocity. Tried it again with Max cases and Max data, and got another match. Good enough for me.
Had I gotten significantly lower velocity, I would have tried the same process with H 110 data. I've done much the same with other powders in other rifles. Seems to be safe enough as long as you use a rifle(s) a lot stronger than your expected results, cases that are small enough to be nearly full, and work up slowly. Once worked all the way through .38 Special, .357 Max, .223, .308, to .25-06 to establish that a completely unknown lot was close to IMR 4831.