At that time some of the original companies were going out of service, their twelve-month enlistments expiring. Many companies assigned to the regiment had been armed by the State of Georgia. Here's a reference from the O.R. dated before the end of 1861 --

The 4,000 cartridges in the ordnance store-room, to which you refer, were made by the Irish Jasper Greens, and are ball, without buck-shot. They will answer, perhaps, for the Washington Volunteers, but Captain McMahon prefers the cartridges with buck-shot. There are no caps with them.

Many of the state firearms available when Georgia left the Union would have been U.S. smoothbores converted to percussion. Companies like the "Irish Jasper Greens" already had arms purchased by the state in 1860 or even earlier. Just my guess, but I would expect these to have included the U.S. Model 1842 --

http://livingonthefield.blogspot.com/2007/10/us-model-1842-musket.html

That may be the firearm in this image --
http://www.framingfox.com/ircolcivwarh.html

All this aside, prior to 1864, many companies of this regiment were assigned to serve heavy artillery in coastal defenses. I'm sorry not to have more --