I just purchased a new REVO MGX-SHS 7.9:1, love the reel, I use mostly 15 lb big game line. I seem to get a lot more over-run on the spool ,than I do on my chronarch mg100 , is it the reel or the line?

or even worse, is it ME ,
I have only been using a baitcaster 40 years ....

you should have a adjustment for that

I do not have revos but if it has a setting on the side set it high like 10 . Then loosen the spool tension and you should be able to dial it in

probably just need to slow your speed down some....

Flourocarbon...

Use Suffix Siege 17#
set it at 0 brake, loosen until your lure begins to drop
dial it back to 50% brake
cast and make "minor" adjustments until you get what you want.
That is my main set up on a 6'6" St Croix and I can throw it as far as I want with no issues.
just my 2 cents & MHO

Revo's seem to be very sensitive to overfilling the spool with line. Might try pulling some off. I usually have about a 1/16th inch of spool visible when I respool. Mono usually doesn't backlash as much as flouro.

Yes it's you...but just you not used to a new reel! :-) As mentioned above, don't over fill, loosen mechanical brake till lure falls and put other brake about 1/2 setting. Then fine tune as you get used to it. That MGX is a sweet reel especially with lighter lures. You will get used to it.

This happens to me when I use a lighter lure.

Sounds like I overfilled ,when grow up fishing a 1973 5000c, you learn adjustment real quick.

now that's a backlash...........