JP Enterprises Silent Capture Spring

[explorecaves]

I'm always sceptical of those huge numbers of rounds. There is no way they shot 500,000 rounds to test them, because the cost of doing so outweighs possible profits so much.

Better yes, 490,000 rounds better? Doubt it.

Easy to set up an automated machine to repeatedly compress a spring similar to the environment the spring would see in the rifle. Run the test through an environmental chamber at the same time to simulate temperature variations (seasons) throughout the year and you have a reasonable test that is repeatable giving you the data to average out the 500k round claim. This is a standard industry practice to extrapolate expected lifetime of any product.