please give me an idea for penetration, expansion and weight retention for 357 magnum 125 to158 grain jhps fired from a 4 inch barrell.

Not enough information in your question to even try to answer. What are you trying to compare?

Given same bullet profile and construction, light ones get there faster than heavy ones.

Heavy ones tend to penetrate farther than lighter ones.

Weight retention depends on bullet design/construction and "what" it must penetrate.

Iowaloha. Nice to meet ya,

Cheezywan

This has been talked about here several times before. You might try the search function and see what that brings up for you. Like Cheezy said a little more info would help us give you a better answer.

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Bob from Idaho