AR-15 Heat Shield and CAA TM3 tri-rail mount

[harbl_the_cat]

I'm quite fond of the CAA TRM3 tri-rail

I was installing one on a new Norc CQA, but I overtightend one of the screws and had to use a washer to space it out, so I could back the screw off a bit without it sticking out into the bottom rail.

With the washer, there was no way to get the heat shield back in place, so I ended up having to drill holes over the position on the heatshield where 2 of the screws were.

Given the fact that the rail blocks 4 of the vent holes on the bottom handguard by way of 4 steel screws, I'm not overly concerned - but still it got me thinking about about the heat shield's function.

Obviously I don't plan on doing full auto, but I'd be interested to see the impact these rails would have (blocking the vent holes on the bottom handguard) with a substantial round count.

Worse case I can see is the screws heating up and maybe melting the polymer - but still anyone have I'm quite fond of these mounts since I can get a forward vertical grip at just the right position for me.

I've heard some models of AR handguards don't come with heat shields - any truth to this?

Thoughts?

 

[zupermann]

Yes, some didn't come with heat shields. But it's been some time since that's been the case. I saw no shields on some SGW and Eagle arms rifles back in the late 1980's/early 1990's.
I think DPMS also sold gaurds without shields called "glacier gaurds"as recent as a few years ago. I don't know if they're still being offered.