Aderrall lasting only 30 minutes?!?

[AbusedTampon]

Earlier today I took 50 mg of Adderall XR beads (expired 4 years) and crushed them up into a very fine powder. Poured it into a square of toilet paper, twisted it, and parachuted it down.
Kicked in 40 minutes after, great euphoria, focus, stimulation etc. But... As soon as I started feeling it I marked the time, and EXACTLY 28 minutes after the marked time, I felt like I crashed.
I have taken this same expired Adderall XR, 4 or so, successful times prior, the same why, only being that I started at 30 mg then built my way up to 50 mg. I only took 45 mg yesterday however, but it lasted a good 2 hours.

So I really am bothered as to why it lasted barely even 30 minutes, is because it's expired? Or because I parachuted it? Just to add, I got enough sleep today and ate a good meal 2 hours or so before taking it, basically nothing was different from the other times I took it. And could it possibly be from taking such a high dose without a high tolereance for it?

Any input welcome, I'd love to hear from an experienced Adderall user haha.
Cheers!

 

[AlwaysClutch15]

The expiration could be a factor, but in my experience, a dose that low wouldn't last me too long either. But I'd still get a solid hour. I'd guess that the active ingredient has disintegrated due to age and has probably reached several half-lives.