Sounds like Franzite. Along with Jay Scott, probably the two most prolific makers of faux stag and ivory grips from that time period. Not particularly bad but not very good either.
If this is plastic from the 50's certainly better then current plastic.
Absolutely not. These days we actually have some really good ivory substitutes made of superior materials. Like paper micarta, bonded ivory, Eagle's UltraIvory and BarS TruIvory. That old stuff is "just plastic".