User blog comment:InfinitysCross/I had a question.../@comment-188.61.41.2-20110731201208

Thermal clips are based on Geth Technology, supposedly. They prevent the overheating problem that soldiers were having (assumption based on in-game info), as well as enabling a higher rate of fire. Ultimately, they're just more efficient.

Also, if anyone can answer this, how is the ammo infinite in ME1 in the first place?