From downstairs where I was CL’d, blessed be her memory:

re: #159 BeenHereAwhile

The Army Said Tank Blasts Don’t Harm Troops. His Case Raises Doubts.
Researchers say troops’ brains may be injured by blasts from firing M1 Abrams tank guns and other weapons, even if they measure below the Pentagon’s ceiling for safe exposure.

… Mr. Beyer joined the Army right after high school and had an unusually long career spent entirely around tanks, including six overseas deployments, three of them to Iraq. His final assignment was as a tank instructor at one of the Army’s busiest training posts, Fort Irwin in California.

A typical tank crewman fires about 120 rounds a year, and works around tanks only for a few years before leaving the military or moving on to other assignments. Mr. Beyer never moved on.

A spokesman for Fort Irwin said that while most training was done with lasers instead of live rounds, a typical tank instructor would be exposed to the firing of 120 to 240 rounds a year. Other tank soldiers estimated that in Mr. Beyer’s career, he could easily have experienced more than 3,000 blasts.

He also was hit by a roadside bomb in 2008 that left him temporarily dazed.

(no paywall)

nytimes.com

As a former tanker, I’d bet that the IED was 90% of the problem if he followed training and protocols. Now, I will admit that his total numbers are high but I’ve know Master Gunners (the guys who set up every tank in the divisions and had to test fire them all and train all the gunners) who had similarly high round counts back during the 80s ~ 90s during the time of the M-60A3 to M1 transition and none of them had issues leading me to believe an undiagnosed TBI from the IED explosion is far more likely a cause in this case.