I read your added notes to the discredited letter from the returning Marine’s father and I can add one more detail. The Iraqis did have 155mm artillery in inventory and we found several South African 155 rounds in country. The South Africans had a very well developed arms industry and they made some of the best artillery and rounds available. They have some advanced 155 rounds that have a greater lethality due to the pre-formed fragments included in their design and some of these have been used/recovered in Iraq.
One of the strengths of the Army National Guard (ARNG ) and U.S. Army Reserve (USAR ) over active duty is that we bring a greater skill set with us when we deploy, both civilian skills and more MOS  schools under our belt. I have several to include more than one Intelligence MOS. [JWR adds: I concur wholeheartedly! The USAR and ARNG soldiers tend to be several years older–sometimes decades older–than their active duty counterparts. Those extra years almost always equate to greater depth and breadth of knowledge/experience/common sense. Many of the military intelligence soldiers that I commanded in the USAR spoke multiple languages and had earned Master’s degrees. The enlisted ranks in the active duty M.I.  units just didn’t compare. BTW, I should mention that this was a humbling experience, as a young M.I. officer with just a Bachelor’s degree.]
If you have any direct contact with soldiers in country please recommend to them that they have their intel people take a look at the NGIC  (National Ground Intelligence Center) website regularly. Any soldier with access to the SIPRNET  [U.S. military data network for handling classified traffic] can find it and it allowed us to stay weeks ahead of emerging Tactics, Techniques, and Procedures (TTP) s. It was not uncommon to find things through NGIC weeks before higher command got the info to us through regular channels. I also found it useful to look at areas (on the NGIC site) that were outside Iraq but were dealing with Islamic fundamentalists. – Anonymous