Russian olive is very poor in tension and tends to have some pretty terrible set problems. Meaning, it will blow up or fail to keep its form and strength. I have tried it myself with zero luck, but I have seen some examples of it online. One man used the heart wood and the sap wood to make a very good looking, but very over-built looking bow. He heat treated the belly to reduce the set with success. That doesn't mean it is a good bow wood like Red Cedar and Osage, but it is still usable with the right skills. Go for the "Hedge apple" if you are new to bow making. The red cedar takes some additional skills to make a bow successfully out of.