I have an older 45 full size, currently I'm using the Wolff uncaptured spring and guide rod. When I look into new springs for this excluding Wolff I find captured recoil spring assemblies. My question is do these fit my Gen 1?
Below is a link to S&W OEM assembly. It appears from the photo to be flat wound does anyone know if that is true? Also does anyone know how many lbs this is?

M&P(R)45 Full Size Recoil Guide Rod Assembly | Smith & Wesson

Thank you in advance for any help.

I have a 1.0 M&P 40 compact with 16,000 rounds through it. It has the factory flat wound captured recoil spring assembly, which works just fine. It makes sense that the full size uses the same design. I have no idea what weight it is. In my 40c, the RSA has lasted from 4,000 to 6,000 rounds before needing replacement. I was pushing it to make go 6,000 rounds, so I 'd recommend changing every 5,000 rounds at least, and every 4,000 rounds if you want to stay on the conservative side.

At one time, S&W would send you a new RSA free for the asking if you were real nice to the customer service person and could make a case for why you needed a new one. It wouldn't hurt to call.

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