I went through a recoil assy replacement on an ATI 3" bull barreled gun. The original recoil assy looked way more flimsy then yours, especially the guide rod head was thin as a Coke can. Yours looks more like one from a Colt Defender, where the head is thicker. The springs are not replaceable, at least not the inner one. There are replacement outer springs but non I could find for the gun I had was fitting in regard to coil amount and length which developed into a nightmare. The dual spring setups are also not very reliable and need replacement after only 500 to 1000 rounds.
To make the story short, I used a EGW reverse plug that would fit a Para P10 and had to make the ledge of the plug fit on the gun. Was quite easy to do that. That might not be the case for you but you need to check. The P10 guide rod, even when made for the P10 3" barrel was little bit too short due to different dust cover length on the ATI so I got one for a 3.5" gun from EGW and cut it to length. The guide rod head needed to be fit with an angle to accommodate the cutting corners of what ATI did with the lower barrel lugs.
I use the EGW ISMI springs for longer lasting use. Would never go back to round springs for anything shorter then 4 1/4" barrels.
I would start looking at the reverse plug at EGW and get a longer guide rod and fit it. The plug on your gun won't work with EGW since they require 0.25" hole diameter, your should be 0.28-0.31" depending on that spring assy. Throw that whole assy away, they are not very good.
I love the gun but the shorties are a hassel to get them run well. Mostly the extractor setup is critical but once that is done they are great.