I recently purchased my Shield 40 cal and attempted to load the magazines... The spring tension is so strong I couldn't insert more than one round...
After over an hour I did get bullet number two inserted
How can I adjust that tension?

Sign me "Weakling"

Get a Universal Pistol LULA.(UPLULA). Walmart and others sell them.

+1 on the Uplula. As was said, many places have them (including your LGS) but here's a link to one (so you're sure on what to get, there are loaders and then there is the Uplula, world of difference) Maglula UpLULA Pistol Mag Loader Unloader Polymer Black

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Minimize the variables

My local Gun Shop had just what you mentioned.
Got one and works great.

Thanks

Thanks, LGS had just exactly what was needed.. The Sweet Young Thing who waited on me knew exactly what was needed, since she uses one also.

Congrats on the new Shield, and being able to get it loaded. I was at Walmart today, and had one in my hand, and put it back. After loading a bunch of mags this evening, I'm wishing I would've bought it.

I found my shield 40 had quite the break in. it was tight at first but after some shooting it smoothed out

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Casey

The trick to loading the mags is to set it on a table and insert the cartridges using your strong hand with your thumb over the back rim to push the cartridge first down, then back.

On the other hand, the Uplula is a very good tool.

BTW, having a magazine sit with a full load does not "break-in" the spring. A spring gets worn down by being cycled so you need to load/unload to get it to soften a bit. The best way to do this is to shoot a lot.