Hahn Precision barrel light mount (w/temp test)

[lindertw]

following wichaka's post in another thread, I ordered a light mount from Hahn Precision. It weighs in at 2.6oz (6.4oz with X300 attached), and is marked that it will work with barrel diameters 0.720" - 0.750"



The mount doesn't work on my Noveske N4 basic upper - barrel diameter is too small and the mount flops around on the barrel when the halves are tightened. I emailed Hahn and to see if they could make a modified version to fit my N4 (fingers crossed ). They don't have any plans to make mounts for barrels that are smaller than .mil standard (I've got an idea on how to modify one to fit my N4 basic).

When mounted on my Colt 6920, there is a small gap due to the barrel diameter. The slight gap shown in the pics above is normal and desired; this ensures the mount is snug against the barrel and not bottomed out on itself. Here are a few pics with it temporarily mounted:











I plan to to tweak the mount a bit so that it fits the bayonet lug better (it just barely goes over the lug now). This should allow it to sit a little further back (closer to the FSB). I am planning to modify a Surefire DG X-series tailcap and attach a flexible tape switch. The parts are on backorder, but I'll post an update when I get the tailcap mod done.

...all I can say is wow! If you haven't used a 12 o'clock mount, you don't know what you're missing. The light is always where your sights are, with no shadows, and the light is equal everywhere.

Nothing I can add to wichaka's quote

===

I emailed Hahn with a few questions, and their response has been added in blue above

[markm]

That positions the light well. But the two things I don't like about it are...

1. It clamps directly to the barrel. It's just a personal thing. I've never liked anything that mounts that way. and,

2. You'd have to run a remote switch for the light. I will never run a remote on any of my guns. Another personal thing. If there's a wire, I'll snag it and break it when I need it most... guaranteed.

[RD62]

I didn't see on Hahn's web site what the mount is made from?

Also it seems that it would be subject to quite a bit of heat, wouldn't it?

-RD62

[lindertw]

it's aluminum (no clue as to the specific alloy). I'm curious to see how well it bleeds off heat too...

I plan to take my handheld IR thermometer to the range and record temps of the barrel/mount/light while I run several hundred rounds through it.

[M1A2_Tanker]

My bet is it works like a heatsink and you'll be out alot of money for a new light, if you put decent trigger time on it. If it were me I'de take it off at the range and only use it for self defense.

.02

[lindertw]

My bet is it works like a heatsink...

you might be right, we'll see! I'm planning to take temp readings at the following places (note "D" would actually be the back of the tailcap vice the selector switch as shown in the pic):





Open to inputs for this experiment, I'll check back before I head out to the range this evening.

[RD62]

Good luck!

I'm interested in seeing your results!


-RD62

[CLHC]

Looking forward to seeing the results you get.

[lindertw]

Testing occurred at the NRA indoor range in Fairfax, VA. Colt 6920 w/iron sights; magazines were a mix of PMAG/Colt/Bravo Company 30-rounders; ammo was Prvi Partizan M193 55gr BT FMJ - 300 rounds fired. I experienced one (1) failure to feed (round 27 of 28 in magazine #3).

Target was a 3"x5" card @ 25 yards, firing as soon as I could acquire the sights but slow enough to keep 'em on the card. Testing began at 7:00pm and concluded at 7:45pm.

Temp readings were taken with a Fluke mini 62 IR thermometer. I did the best I could to get good temp readings; if something seemed off I ran the temp again to verify - curved surfaces can be tricky The temp reading on the handgaurd was at the 2 o'clock area.

The light held up well. The bottom plate that snaps in the picatinny rail showed no signs of melting/deformation. The plastic side rails that screw into the bottom of the light seem soft. I can't remember if these were the same hard polymer as the bottom plate or not. I'm going to keep and eye on them, and order a replacement set from Surefire just to have on hand...

What's not readily apparent in the pics from my first post is that the mount only touches the barrel at point "A" shown; the rest of the mount is free float.

[CLHC]

That's interesting temperature readings you've got. C, D, and E can get "up" there in heat to say the least. Just curious if you've able to simply touch the switch at the recorded temperature? Obviously with gloves, it's no problem.

Thanks for posting!