[gradsusr] shift longitude range in grib2 file from 0->360 to -180->180

[P. R.M.]

I have a grib2 dataset (gfs winds) that spans 0-360 degrees longitude, in 0.5 degree increments.
I need to convert this dataset into the range from -180 to 180, so I need the grid to start at 180 degrees longitude instead of at 0 degrees longitude. (fyi, the 0-360 range simply doesnt work for a custom application that Im running).

how can I perform this conversion, and store back into grib2 format?
can this be achieved by simply using wgrib2, or would I need to convert the data in grads, and then export&convert back to grib2?

please help,
thanks,
p.r.
 		 	   		  
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