Thank you both for your responses, to me spears and pole arms are very different weapons. Now I agree that in 5th melee weapons are highly generic, making pole arm probably the closest fit. But in many other systems and I think previous editions fixed bayonets tend to be given the same stats as spears, however the line from R&G lacks an accuracy rating, making it's not really unusable, unless you're meant to assume it has the same accuracy as the attached gun, which I doubt, given the rifle butts don't.
I checked the R&G errata and it's not addressed there ether, after reading over the rest of R&G I think i'm inclined to use the Javelin rules. Though I have to admit that doing so probably overly generous given that its' accuracy is listed as Physical limit.
It'll do until greater clarification can be achieved. Is their a stated npc somewhere that uses a spear in 5th? I think I recall one. I'll go start on the adventure books.