I do not know much about Magtech except that they manufacture magazines for semiautos, never heared they made ammo.
I think you're confusing "MagTech" with "MecGar."
MecGar makes magazines.
Magtech ammo is pretty decent stuff for inexpensive manufactured ammo, IMO. It became my retail .44 magnum load of choice due to cost and the feel of the recoil. I tailored a reload to feel as similar as possible and it is my favorite reload now. The brass gives good longevity and I've never had a squib or a bullet back out of the case under recoil from the factory loaded ammo.
I've used their 44magnum, 44special, 45acp, 9mm, 357 magnum and 38 special. In rifles, I have used their .308 winchester. Their .308 even had annealed case necks... something lacking on remington, federal and other non-NATO brass.