You need to get yourself a chronograph. Simple, reliable and accurate units can be purchased for around $75. Published reloading data will give you a good idea of what speeds you can get at acceptable pressure levels with a particular powder/bullet combination. Extensive testing has shown that working up to published velocity levels is a better indicator of pressure than powder charge weight.

John Barsnes did a great article on this subject in handloader magazine awhile back. He used actual laboratory pressure data and compared it to "traditional" pressure signs. He found that good quality rifles and brass will often tolerate extreme overloads with no stiff bolt lift or cratered primers. The chronograph showed the overpressure everytime.