How is getting nothing better?
If there is a real chance you can get the whole enchilada, go for it.
If you have to give up something you currently have, or throw someone under the bus, in order to get this, you have a different problem to consider.
But to get part of what you want, while giving up nothing? Seems like a no-brainer to me.
I can only think of two possible exceptions:
1-If you really need some votes on pure bills to distinguish the sheep from the goats and you have the ability to retire the goats next election.
2-If you are worried that going part way makes it harder to advance to the final goal. For example, off-duty or retired cops get some special privilege. That sub-group no longer has personal reason to work for the rights of the whole group.
In most cases of reality, neither of these really exist and incrementalism is a very solid path to getting what you want.
I'd predict that if you can get the 30 round limit this year, you can probably get most LE agencies to go neutral or better on eliminating the ban entirely 3 or 4 years down the road. Are they really going to mess with prosecuting someone with a 100 round drum magazine for his 10-22 at that point?