This is a naturally overgassed 16" Carbine M&P15 SPORT (Original Version with 1/8 5R Barrel) overgassed as all are.

I'm on a mission to tune it with added mass with Buffers and "possibly" a stronger spring as I ordered a JP- Tuned and Polished Chrome Silicon Buffer Spring with 7% extra power!
(sorry for the lengthy post in advance).

I already added an H buffer awhile back and it made it much smoother, being still want to smooth it out more, but do not want to put it on the border of risking malfunctions, just want it less gassy than from the factory and maybe like 1 step below as far as it could be pushed and to where PMC .223 55gr can still be reliably fired reliably, and not risk malfunctions once a little dirty as these Carbines are known to push on and on in factory configuration, so just want to make it smoother and have less recoil/ muzzle dip, and parts wear.

Just put in a Chrome Silicone "Damage Industries" Buffer Spring (normal strength, 100x longer life expectancy and less Twangy) and haven't used it yet, but ordered a "JP enhanced spring" that is 7% stronger as an add on to an online order to get a discount.
The JP's power is HALFWAY between a White (normal power) Sprinco and a Blue (+17%) Sprinco.

So its either add the new JP buffer spring with my current H buffer,

VS

Keep in the Normal strength Damage Industries CS spring and add an H2 buffer!

Which pair would add the most reliable resistance and is that 7% extra spring power MORE, or LESS than what an extra Tungsten weight would add if I went from an H to H2 buffer with normal spring???

I still want to be able to run PMC 223 55gr, although I have more PMC Xtac 556 on hand but don't want to tune it too far.

I've read archives here of many having great success upgrading to an H2 Buffer, M16 Carrier, and Factory Spring.

So even though the Sport came with a SA BCG and I have a spare ToolCraft Nitirde M16 BCG on hand, the factory SPORT BCG is said to be terrific quality as "Microbest" makes M&P BCGs supposedly...

Any suggestions from those who have done this process??