I would be very reluctant to recommend a lead sled..using this too much will damage your stock..no where for that energy to go and it will be transmitted to the stock.
Your mostly correct...only you forgot one other option...The energy also is delivered to your scope and mounts.[
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In fact I have a personal friend that shoots a .376 Steyr...(admittedly a stout recoiler). Heblew through
three scope while using the "Lead Sled"....And not exactly cheap ones either...Two Conquests and one Burris Euro Diamond.
Not exactly "proof" that the lead sled is a scope killer....but certainly very likely to be "supporting evidence".
Speaking for myself...I will never use one...The reason is, the more likely you are to need to use one, (higher recoiling guns),the more likely you should not be using it, (highest recoiling guns on the lead sled are clearly the most likely to get damaged.)