I used Acetone on all of mine to wipe them down.
The paint I used was Fusion paint by Krylon.
It did not hurt a thing.
I taped the lenses on my optic, wrapped some blue paint tape around the optic controls,stuffed a rag into the magazine well, and shoved a cleaning patch into the muzzle.
I used 2 base coats of khaki on the rifle, then let it sit for a couple of days.
Next I used a light coat of dark OD green, spraying through a screen or another piece of cloth with small holes to offset the base coat, then let that sit for a couple of days.
The last paint coat was dark earth brown in a light dusting over the while thing, again let it sit for a couple of days.
The final coats were clear flat clear coat, then let it hang in a heated box for three days.
The last thing I did was take "00" steel wool and buff any shine off of it.
I've done at least 20 rifles for locals and myself in totally different paint patterns and haven't had a single complaint yet.