Melting Magpul MBUS?

[cfusionpm]

So I had a thought today after taking my piston-driven Ruger SR-556E AR out to zero my new Magpul BUIS... Since they are essentially made out of plastic, is there any issue of them sitting on what ends up being the hottest part of the gun? I could move them further back a few notches to the handguard part of the rail, but I'd rather not have a smaller sight radius. That front end gets pretty hot after just a few mags. Am I being overly paranoid, or could I genuinely damage the sights with the heat?

[tuna quesadilla]

Not sure about piston rifles, but it is documented and well-known that DI gas blocks put out enough heat to melt MBUS sights. I'd play it safe and get a metal front BUIS.

[djleisure]

Yep there is an issue. You are advised not to do it. They are meant to go on handguards, not gas blocks - a couple notches won't kill you OR get a full-metal front sight.

[Merc1138]

Pay the cash to get a metal front sight, or move it back onto the rail.

Doesn't magpul even say in their documentation not to put it on a gas block?

[tacticalcity]

For now just move it back a little bit onto your handguard where it won't get hot enough to be an issue.

Save up for a set of Troy sights.

[G-forceJunkie]

I hate to be an ***...but did you RTFM?

"NEW Features for GEN 2

* Reduced size for greater optics compatibility
* Spring-locking front sight post holds consistent elevation

NOTE: Cannot be mounted to a railed gas block due to excess heat issues.
Front MBUS must be mounted to a railed fore end on the same plane as the receiver rail. Because of this the sight is also not compatible with MOE Hand Guards."

[mlevans66]

Yeah man they are going to melt if you keep them on your gasblock. Even if it's a piston cause that part get the most heat I think.