Hello there!

Like I said, I've been listening to djent stuff and writing some of my own for a while now, but I need a 7 or 8 string, ideally for that mega brutal drop tuned stuff. Since I'm skint, though, I can't afford a new guitar, so I thought that I'd try a different solution.

I'm not really going to be playing lead stuff on it, only chuggy djenty rhythm things, so I decided to restring it and tune it from B to B, rather than E to e, so I had the drop tuning thing of a 7 string, without losing a load of money.

The problem is, that it's pretty stubbornly refusing to stay in tune, and the intonation is so far out that I can't move the saddles far enough to correct it. I'm not sure what's causing the issue, whether it's the guitar, or this was just a ridiculous idea in the first place. It's probably worth pointing out that I'm already using super-heavy gauge strings, so I don't think the problem lies there...

Any pointers as to where I'm going wrong?
I am Rob Rideout! Wearer of Pants!
I was gonna recommend putting on some heavier strings, but it looks like you've already done that. Does your guitar have a floating tremelo?
for tuning- take a look into how you wrap your strings at the tuning posts. If you can't get tuning issues resolved there maybe look into better tuners? what kind of guitar are you playing?

for the intonation issues, were you trying to intonate with new strings? if not, try new strings and report back.. if they're new strings but still too far out, then that's a bit tougher. How far out are we talking?
I did the same thing to one of my guitars and never had a problem.... what kind of tuners do you have?
“More metal than your gran’s left hip.” - Paul Allender on his PRS signature guitar