If it's recommended I guess it works then. Problem solved.
I've seen more people bitching about how to fix problems with an A5 setup who refuse to listen to reason because the a5 system "fixes" a problem they never had with bolt bounce. The whole a5 system is managing a problem that is not worth the effort, ESPECIALLY for people not shooting full auto. It makes troubleshooting stuff like this a pain in the ass.
If it's the mag, you have basically have one choice. When the bcg/buffer bottom out, the shock is causing a bullet to pop up out of the feed lips. Odds are if the feed lips are this messed up, your bolt over base failure will not involve just one round and will look like a double feed. Odds are that this will be limited to specific mags. This is probably not your problem.
If it's not the mag, you have two choices.
1) the whole BCG/buffer combo isn't getting enough oomf and the bolt isn't clearing the mag and it is dragging the bullet halfway out of the mag from friction with the side of the bullet rather than things pushing on the case rim from behind. This will seldom look like a double feed.
2) The whole BCG/buffer combo is getting WAY too much gas and returning to battery REALLY fast before most in spec magazines can pop a bullet up to the top. In the free world this is a bit easier to troubleshoot because you try it with a full 30 round mag and that slows down the mag and generally causes a failure to feed with the bolt slamming home on an empty chamber. This usually doesn't look like a double feed, but due to the vigrous movement can sometimes make your mag do weird things. It also is more likely to really bend the crap out of the bullet caught by the bolt.
You are running a full weight m-16 style bolt.
With a +15% spring rate spring.
With a H2 buffer.
With a carbine length gas system (7.5")
With an 11.3" barrel.
So you have a ton of port pressure, but you have a whopping 4" of barrel for dwell time (~4ms), and an unknown size gas port.
You know what has issues with too little dwell time and reliability? rifle length gas systems on a 16" barrels. That have a similar 4"/4ms of dwell time. That's why you don't see people with 18" barrel and rifle length gas and 6" of barrel for dwell time beefing everything up. That's why the stretch 16 barrel cuts it back to an intermediate length gas system, and those who want to sell a reliable gun with a standard gas system either use a mid length on 16, or a rifle length on a 17.X" barrel with some math done on the gas port.
Here's a nice article on the subject
Your heavy BCG buffer set up delays unlocking, which reduces battering, but without enough dwell time, you won't impart enough momentum to cycle it correctly.
If you swapped the super 42 spring for a sprinco green or red, you really didn't do anything.
Having a heavy buffer and heavy BCG in theory makes it take longer to unlock. You don't have the time to wait before running out of gas is my guess. To keep it from battering things, I'd decrease the mass of your BCG/buffer stack and not dick with reduced power springs until last resort.