BCG and Spring questions
 

Is it better to run light weight bolt carriers and light springs to enhance the reliability of the 300 since the gas pressures are low with subsonics?

If you did this, would it cause issues with supersonics?

I'm working on a 10.5" upper and was wondering if these things might aid reliability.

get the gas port in the piston position and dont mess with carriers or springs. Adjustable block will allow you to optimize for both.

I have a 9.5", I find that I can not push supersonics as fast with the block set to subsonics.