Why a springpack and not just a spring?

[BlackHalo]

No idea if there is a reason or not, but why did AGD decide to use a springpack instead of just a regular spring? Just something that struck me as strange.

I tried searching for an answer, but to no avail.

[Coralis]

probably because the life of spring pack is longer and its more precise at adjust velocity ... if i had to wager a guess

[SR_matt]

also more force in a smaller area

-matt