My 16” mws mars H is really over gassed. It’s not terrible without a suppressor but once I put my sandman S on the recoil is substantial and the ejection is very violent. The rifle exhibited a couple malfunctions while suppressed as well.

It is stock from LMT with H3 buffer, is the slash XH buffer/spring  going to solve my problems?

I don’t want to throw $140 away if it’s not going to work.

Went with the brt 50/50 suppressed/un suppressed. Ran 100% with various handloads and factory ball.

Recoil was much softer and my brass wasn’t launched to the next county and dented like before.

I have a MARS H CQB as well as an older MWS.
Slash's buffers will help.

This guy did exactly what you are contemplating and it worked well for him.
https://www.youtube.com/watch?v=WX1kNtalmFw

The route I went was to install a PWS H4 buffer along with with swapping out the SA bolt carrier with a FA bolt carrier.

Those 2 changes really mellowed out the recoil and the brass ejects at about 4 o'clock about 6 feet away.

I haven't messed with the spring but I hear getting one of those Sprinco springs will tame things as well.

Mine started as a mars cqb and I ended up trading the pinned 13.5 barrel for a 16”.

I decided to go with a brt gas tube. I picked the 50/50 suppressed/ un suppressed.

If it’s still too gassy I’ll try out a springco spring and then a heavier buffer if need be.

From Snipers Hide:

BRT EZTune Gas Tube.