The CS45C is the blue carbon steel frame CS45. The CS45D is the DAO variant and the CS45S is the stainless steel variant. They all use the same recoil spring.

Yes, a 4506 spring will work in all revisions of the 4506.

Any 39XX series recoil spring will work in a 3913TSW. For that matter so will any 69XX series spring. Because they all use the same recoil spring as well. Hope this helps. Regards 18DAI

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