6.6m WRA Carbine build date?

[cpc]

I’m trying to figure out the approximate build date for a WRA carbine, 6.600xxx. I know the WRA polish room dates are available for Garand receivers and wondering if the records were also found for the Carbine? The books I have and charts on line indicate blocks of dates and are not very specific, for example this one would probably be Jan45. However, when I find a few close numbers on line the experts say early mid 45. Just trying to pin down a better date, my guesstimate based upon what I’ve found is Apr/May. Can anyone on the forum provide a more definitive or accurate timeframe? Regards