sniper81,
The buffertech buffers are horrible. I tried one on my Mini-30, and it caused some major problems.
Ruger considers the linkage at the rear of the gas operating system, in front of the reciever a buffer.
If you decide to put a buffer on your Mini, I would suggest the thin 1911 buffers. Although, a far better use of your money is with a reduced diameter gas system bushing kit from Great West Gunsmithing.
Combine the correct bushing with a heavier weight recoil spring, and action will cycle perfectly. I also found that changing the bushing/spring decreased felt recoil, and decreased muzzle rise. Neither of those are benifits of buffers.
Charlie