I have often wondered where the HOUSTON ARSENAL got the idea to put multiple flame grooves in some of their small caliber field artillery ammunition. It was expressly forbidden in correspondence from the Richmond Arsenal, as seen below. The regulation arrangement was a single flame groove cut into the sabot and bottom bourrelet. The Richmond foundry of Snyder & Walker added 3 flame grooves by mistake at the end of 1862. When the first of their Sept. 1862 output arrived at the Arsenal in early Nov. 1862, they were included in the shipment to the Western Theater later that month. The first item pictured below was among those shipped west and somehow ended up at Houston instead of Vicksburg. How could the Houston founders know that this use of multiple flame grooves was a screw-up? Apparently, they copied this latest design from 'almighty' Virginia. Snyder & Walker had later govt. contracts for 3 inch ammunition which they produced without flame grooves. When you see a Mullane or 3 inch Read with a single flame groove, you can be fairly certain that it dates from the summer or fall of 1862. Adoption of McEvoy's fuze igniter at the start of 1863 made the grooves unnecessary.
The full color shell pictured on the first page below is currently for sale on Mike's and Carl's "Bullet & Shell" web site. I lifted their pictures to present this analysis. I have purchased from them the $285 3-inch Read from VA seen on the site which I am certain was made by Samson & Pae during the end of 1862. I will write it up for the site after it arrives. I think you'll find it interesting.
Woodenhead
