I can tell you, even if your doing everything right, those little compressors can and do move around a lot, and like in my case, i had a compressed 2006 ford f150 front spring, i noticed once had moved "so both compressors were not directly across from each other on the spring anymore", well i went to losen the tighter one to start releaving pressure, the spring cocked sideways like a bullet and shot the spring compressor "IE Bolt with threads and two hook arms" into my face.
I had glasses on but it put a permanent dent into my forhead above my right eye. I never blacked out "or went to the hospital" which was stupid at the time because i obviously had a concussion from it. Its about 5x worse than getting hit in the face by an ultimate cage fighter on steroids lol.
A month later the swelling went down fully and realized that there was a dent... the minor swelling that lasted a couple weeks fooled me into thinking it was all better, when really it hadn't gone down all the way, and when it did, you can see right where i got hit.
I'm sure getting hit "by the spring" would surely kill you.