That looks like normal compression for a good bolt spring.
The only way to really know for sure if the spring is bad, is to measure the amount of force it takes to compress it a given difference. Since that if more difficult to do, we just use the simple look and see method. However, the best measure is if the gun is cycling properly. If you are getting bolt stick issues when all other parameters are set properly, then it is most likely a weak bolt spring. This was easy to determine on the level 7 mags, but is not so easy on the level 10 mags. The bolt spring is a consumable item. Every so often (usually around 30000 cycles) , you should just change it as a matter of doing your general maintenance.
Except for the Automag in front, its usually the man behind the equipment that counts.
I just had a curious thought. I work with valve spring components. if someone were to get me a measurment of the spring height in gun at rest and bolt forward I can get you a measurment of how much force the spring is actually putting out
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the machine I have measures spring for raccing
Without measuring the force and the distance, can't calculate the spring constant. Once the spring gets used a bit and is weakened, the spring constant will change. Ideally, the spring should last and be the same after 50000 cycles as it is when new. Due to the stress placed on it, that is not the case. The original value will only be valid when new.
Once you do know the spring constant, you can determine the force exerted by the spring at any given compression distance. The starting force of the spring in a mag can then be calculated by putting the valve into the back of the body until the front of the bolt spring makes contact with the body washer, then measuring the distance the valve is from the back of the body. This distance will be the compression distance when the bolt is at rest in the body, and given the known spring constant, the spring force at that position can be calculated. Knowing the distance that the bolt travels, you can also determine the force exerted by the spring at the far end of the cycle as well.
... I was just gonna put a spring on it and turn it on.