Which of the two do you recommend and why? I've had good luck with both on firearms but never had an optic done.

I'm not interested in rattlecanning it and don't care for Duracote.

I honestly do not see a difference other than Cerakote gives instructions on using their product at low heat so common sense says 2 hours at 160-180* works on Glocks so it will work on optics while KG just says 325* (I think that is what I remember) for an hour. I do KG exactly like cerakote and have good results.

I would not heat up optics at all.  Too much to go wrong.  If you don't like Duracoat, then try the new air-cure KG Gunkote stuff.

If you try and make heat cured coatings work on optics at low temps, it might not be very durable.  I know guys have experimented with this on polymers, like Glock frames and so forth, but with optics you are talking about nitro purged containers, sealed with lubricants and O-rings, not to mentioned any electronics, such as red dots or illuminated reticles.  All of which are in danger of being fucked up with excessive heat.  I'm not sure why you'd want to risk it.

At least with the new series KG stuff, you have the durability of KG Gunkote, without the heat cure.  So it's tailor-made for optics and so forth.

I have no idea how many optics ( Nightforce, Vortex, Aimpoint, ACOG's etc... ) I have done but have never had any issues baking at 140* for an hour. If you ever leave your rifle in your truck in the summer it gets up too 120*-180* sitting parked in the sun so they are built to handle some degree of heat. I am not a fan of the air dry stuff, it takes weeks to fully cure and is not as durable but I have not tried the KG air dry stuff, just the 2400 series.

Each to his own; I realize there are many techniques and people that make them work.  I am old school and pretty conservative on this stuff.  Others push boundaries.

The KG air cure stuff is a decent alternative to Dura coat.  And since you don't have to mix hardener, you end up using less per job.  I hate having to throw out good Duracoat when you mix up too much.

I’ve heated my Leupold scope up to 150 degrees.

No issues.

150 is enough to heat cure cerakote.

I’m talking the H series.

Just be sure, double sure your oven or toaster is at 150 and not set at 150 but actual temp is 192.

I've used KG Gunkote for many years and if you call KG and ask the owner who I am they will tell you about me.  My stuff is in the booth at shot show every single year, period.  I also have stuff in various other booth's at shot and do quite a bit of OEM work with larger companies.

Yes you can get KG down to 180, you will need the low temp additive.  It's added 2-3% by volume.  Using the low temp you will bake it 180

KG cures at the following without low temp
325 for 1 hour
250 for 2 hours

KG cures at the following with low temp
180 for 1 hour

With optics I use the low temp addative.  I don't trust blasting the part in the blast cabinet and hand sand it with 480 grit sand paper lightly around all the surface area.  I also mask the hell out of it with high temp tape so it can stay on during the bake cycle.

I've yet to have issues with any decent glass such as vortex, leupold, nightforce, us optics, burris (higher end stuff).  Cheaper stuff like barska and similar i'd stay away from.

How about heat curing optics on an oven that the lowest temp possible is 170 degrees?

My concern is basically the nitrogen purge... NIC says they do scopes all the time in training at 150. I just don't want to Guinea pig a $3k optic....

you could make your own oven, make shift insulation box/crucible use a heat gun as the heat source and control the power to the gun with a digital thermostat. A raspberry pi could probably be used to make a more complicated set-up.