Gas Line Size

[mhild]

I have a 1/2" gas line stubbed out from an outside wall on my patio. I am going to to extend it to a fire pit that's about 20' away, using MDPE pipe. If I use a 1/2" TO 3/4" 90* EL AT THE HOUSE AND THEN RUN 3/4" MDPE pipe to the fire pit, will that hurt anything? Will it increase my BTU rating by doing this? The main reason I need to do this is, I can't find a 1/2" meter riser anywhere. Hopefully this makes sense.