If we are talking about loads listed as maximum or even 70 percent of maximum I would agree with Squid Boy and Ric.
However, if we are talking about 5 grains in your Howa in 223 or 22-250 with a 70 grain cast bullet as I think you are, the short answer is yes.
Powders with similar burn rates as published by Hodgdon, Western, etc can be safely substituted at the very low pressure levels caused by five grains of powder in a modern rifle in those chambering. The load may be unsatisfactory because of poor ignition, unburned powder or fouling problems but shouldn't be a safety problem.
At the very low level of 5 grain for these calibers I believe you will may have better luck with burn rates faster than WC 296 and closer to Bullseye, TiteGroup, 231 etc.
I have been doing such things in 222s and 223s for about 60 years and have never seen any indication of excessive pressure. My match cases used for such loads are on their 55th reload.