i think mod have problem i tried another mod no problem like this,by the way i am using kanthal 28ga and i tried with nautilus2s 0.7 ohm coil problem still same
I really don't think it is a problem. If I'm understanding you properly, your .7 ohm coil is showing as .76. Then when you press fire, it jumps between .76 and .79. Is that correct?
Coils aren't entirely consistent when they're made, so it's not unusual for a coil with an official rating of 0.7 ohms to actually be 0.76 ohms. Mods aren't perfectly accurate either, so one mod might show it as .7 while another shows .76. Anything between about 0.6 to 0.8 isn't unusual and isn't usually a problem.
Then when you press fire it jumps up and down a little. Since it's kanthal, it's just a small variation you're seeing. If you were using a stainless steel coil, you might see a difference of 0.3 ohms or more.
The changes you're seeing are normal variations - as long as the vape seems normal. One other thing to mention is that a coil's resistance can increase over time. It would also be normal for a 0.7 ohm coil to creep up .1 or .2 ohms over a few weeks.
If your coil suddenly jumps to 0.95 ohms or down to 0.45, then I would think that something's going on. Right now, it sounds perfectly normal.