George,

You hit the nail on the head! The Texas 1st Heavy Artillery, Cook's, (organized by the increase of the 3rd Artillery Battalion to a regiment on April 28,1862) manned the heavy coast type guns.

Company A,B,C,D,E,H,I,K and L - Battle of Galveston
Company F,(Davis Guards) - Battle of Galveston and Sabine Pass

The 4th Texas Artillery Battalion (Shea's) Company A and B - Battle of Lavaca, Oct.31, Nov. 1st.

I hope this helps,
Gary D. Bray