Hey there guys...

I currently have
Ibanez SZ320 + Metal Muff + randall amp (rg75D)

The randall doesnt provide enough gain for me, i need that, parkway drive, as blood runs black, diablo kunda gain... heavy, deep gain...

I have .53 or .52 strings, so i have heavey gauge... What else can i do (besides getting a better amp) can i do to obtain a more metal sound?

tuning is in Drop B

KInd regards

Ibanez SZ320
Randall RD75
Mesa boogie single recto series 2
Line 6 Toneport
Mesa boogie single recto series 1
Digitech GNX4
slap an EMG 81 on ur guitar if ur needing a good metal sound
PRS Single Cut Trem
Ibanez PGM-301
Rickenbacker 650D
Jackson RR5
Taylor 12 String acoustic
Yamaha RBX 5string bass
Hughes And Kettner Trilogy w/ 4x12 HnK cab
surely the metal muff can provide adequate gain....
Youtube covers

get a proper high gain valve amp, thats a necessity for metal rivera do gd ones. if nt get a pod a pocket pod is gd enuff u can create prrety heavy sounds from there. also on tone on guitar mess aroung with knobs , knock off treble keep bass up use treble pick up. these little things count
Put your penis in a blender, nothing is more metal than that. Once you've done that it won't matter what your guitar sounds like, you'll be more metal than anyone can handle.

But to actually answer your question, all of those bands, get those chuggin tones, by overdriving the tits off high gain valve amps. 5150s, Diezels, H&K, Rectifiers etc. There's unfortunately no other way to get that tone convincingly without that sort of sexy gear.