Consider this... the tapered section will fit inside the coils as it compresses. The symmetrical spring will have a tendency to actually bind as the coils compress.
Yes I feel it was just a bad batch of springs but I also feel that if a man is not 100% comfortable in his gear, he needs to make the needed changes...
I have considered this...but as a benefit to capacity only. Once the spring is compressed/uncompressed, it seems as if this design leaves a bit more room for binding/loss in tolerance(s). I have experienced this firsthand. Im not making this stuff up.
As a "for instance," I noticed, upon cleaning the weapon prior to shooting it for the first time, the tapered spring tended to "slide" around a bit more when mated to the follower (as well as the spring retention cap) vs. the more "traditional" springs used in other shotguns I own. It just seemed to me, at the time, that this "slipping" was a possible invitation to binding/misfeed issues.
Sure, in theory it may be a nice idea, but in reality, isnt it possible that this design just may not be ideal? I could be wrong here and will admit it if I am. But, if this tapered design was the "stuff" then Im assuming others would adopt it as well, no? Now, I will always stand by my belief that Mossberg has implemented many useful "against the norm" features within their shotguns. In fact, it is some of these very features that continue to draw me to their guns...the 590 line in particular. But, even the best miss the mark from time to time.
BTW- I am now 200% comfortable with my 590 (upon going with a Wolff spring and Vang Comp follower) as I now have over 500 rounds through this gun without one failure. With the stock setup I experienced 3 failures within one hour. Later on, when I brought the gun home and stripped it for cleaning, I discovered that the factory spring had literally bent back into itself. Crazy yes, but true.
Either way, Im not suggesting the OP run right out and replace this stuff right away. If his gun works as is, then thats a good thing indeed. After all, "if it aint broke, dont fix it"...as the saying goes. However, making him aware of such issues, should they rear their ugly head, is something I just felt inclined to do.