The Bomb Damage Assessment of the Murrah Building run by the range at Eglin AFB was as convincing to me as any of the other factors.
Two or three tons of ANFO in a Ryder van did not bring that building down.
http://911blogger.com/news/2008-04-24/blast-effects-study-does-not-support-single-anfo-bomb-okc
https://www.constitution.org/ocbpt/ocbpt_01.htm
Was not an ANFO bomb - was amononia nitrate mixed with nitromethane - made it much more powerful.