In answer to your question,it would appear that General Van Dorn removed completly that machinery for manufacturing small arms in the Little Rock Arsenal East of the River.And that General Hindman ordered the manufacture of arms making machinery at Arkadelphia(later removed to Tyler in 1863)to be made from Scratch.. OR.I Vol.13 page 32.

The next Albaugh says we hear of the Little Rock Machinery is a letter from President Davis to Governor Flanagin dated July 15,1863(obviously after the loss of Vicksburg)in which Davis deeply regrets the removal from Arkansas of that machinery and that the last information he has of it was that on the 9th of July,63 it was at Jackson,Ms.And that the Ordnance Officer at that place said he should probably be compelled to send it back to Alabama...OR.Vol.22,Part II,page 932.

As you suggest,it would seem odd that this valuable machinery would have been at Jackson at this time and not having been destroyed earlier by Grant's Federals...

MWT