I've extracted bridgesii a couple times already. Usually have your standard 12 inch cuttings about 3 inches in diameter; but this time I bought 62 inches of cacti with fluctuating diameters none being 3 inches wide.
My question is I had 4.5 lbs of the achuma on average how many doses would that yield by its fresh weight?

Based on the experience of others and chats about this topic, i would guess between 4-6 mild to medium doses depending on your sensitivity, tolerance and the strength of the cacti.

4.5 lbs you say...

2.25 ego flattering doses i say...

each lb can be estimated 700 mg, but that could be totally off if your specimens genetics are not as i anticipate