https://www.dnatactical.com/products/surefire-g2-nitrolon.htm

I have the above light mounted in a Daniel Defense M-lok mount on my rifle and want to get an LED upgrade kit.  Does anyone know what kit is appropriate for this light?

Malkoff m61. Although with the plastic bezel you’ll probably need the “L” model for lower heat buildup.

Thanks Grizzley.  I thought about buying a Surefire kx4 head on Ebay.  I've read where it's compatible with the G2

Your light has a temp push only on or twist constant on tail cap and a polymer bezel which won’t work with a high output head. You would be better off buying a Surefire G2X Tactical for around $80 if you want to stick with the round handheld type light.

That KX4 head is only 120 lumens.  The G2X tactical is 600 lumens.

Thank you Sir

For an LED upgrade, Malkoff is the way to go.  Different power levels, different color temps (cool, neutral, warm) available. But as others have noted, if your G2 has a plastic head, then the full-power M61 may not be advisable.  The neutral version with the Luminous SST-20, 4000K 95 CRI is the best looking LED light I’ve ever seen, and I’ve tried a bunch.  Even if you decide to go another way for a weapon light, the G2 + Makloff M61NL would make a really nice handheld.

The modern G2X costs not much more than a Malkoff drop-in.  But lately they seem to come with a click-on / click-off type switch, and I’m not keen on that for a weapon light. I’d rather have something where if I let go, the light goes out.  Your old G2 is like that.

ETA:  the kx4 is pretty lame by modern standards. I have a few and don’t use them.

Thank you for the input.  I just ordered the Malkoff M61NL

As someone who's been down this road with the 1" flashlights, all I can say is that I eventually discovered that there's really no substitute for the 600DF/300DF style bodies. They're smaller, but throw a TON more light down range with the right head. At least for my current shooting needs, I find high candela lights to be much more useful than high lumen lights. I guess I'm saying... keep your expectations reasonable.

That said, the Malkoff is a not a bad interim solution.

My order came in today and I can say without hesitation, that Malkoff makes a quality product.  Exceeds my expectations.

I upgraded several of my old Incan surefires with various Malkoff m61s. They are a huge improvement and offer long run times, but I’m think I you would be happy upgrading to a modern scout based design from Modlite or a new 640 Turbo. Even my old 600U seemed to leave the Malkoff 6v stuff in the dust.

If you never shoot in the dark and it’s a just in case thing, that G2 is fine I suppose. It will definitely do the job, the new lights just do it a WHOLE LOT BETTER.

@doom1430

Any issues with overheating?  Also, have you tried using 18650 instead of CR123?

Pretty sure you can't fit an 18650 in a G2.

Yup. The G2 body's inside diameter is too narrow by 2 mm, and can't be bored out larger.

I'm using a single 16650 in my G2 (as well as in my 6P, C2, M2, etc.) or I can run two 16340 batteries for more voltage with less amperage stored.

Thank you, gents.  I noticed that earlier today on the Malkoff site: "This battery will fit Malkoff MD Series bodies.  It will not fit stock Surefire bodies."

GunnyG, are you finding the run time with 16650 reasonably close to two CR123As?

I would say better: I use Malkoff's 100 lumen M61LLs in mine, and I get many more hours out that with a 16650 (3.7 volts dc rated at 2100mah), than I would from a pair of CR123 (Malkoff cites 10+ hours of runtime for a M61LL on 2 CR123s (making at most 6.4 volts, still at 1500mah)).

Bottom line up front: I am sorry to say that I am remarkably underwhelmed by M61NL.  Too much spill; not enough throw.  

Perhaps my expectations were too high, but I may actually prefer the original incandescent unit to the M61NL.  I will most likely return the latter after I give them one more chance tonight.

I compared them to different lights in the following conditions:

1. Indoors, low-light.  M61NL vs.
    a. Incandescent G2.  Both have their pros and cons, but neither seemed to have a significant edge over the other.
    b. Surefire X200B.  The X200, which I don't believe exceeds 120 lumens, outperformed it in just about every way.
    c. Surefire G2X Pro (older model with 200 lumen in high).  No match.  I don't even know how they can both be rated at 200 lumen with that much of a visible difference in both throw and spill.
    d. Streamfire Microlight USB in high mode.  This did better too.  

2. Indoors, no light, large room.  
    a. Incandescent G2.  The M61NL did much better in this setting.  Probably the only setting that it outperformed the incandescent G2 by significant perceptible margin.
    b. Surefire X200B.  The X200, which I don't believe exceeds 120 lumens,  did better.
    c. Surefire G2X Pro (older model with 200 lumen in high).  No match.  I don't even know how they can both be rated at 200 lumen with that much of a visible difference in both throw and spill.
    d. Streamfire Microlight USB in high mode.  This did better too.  

3. Indoors, no light, hallway and transitioning from room to room.
    a. Incandescent G2.  Both have their pros and cons, but I would give the edge to the incandescent because it did not overexpose the threshold while underexposing what's behind it.  The M61NL overexposed the threshold enough to be bothersome.
    b. Surefire X200B.  The X200, which I don't believe exceeds 120 lumens,  outperformed it in just about every way.
    c. Surefire G2X Pro (older model with 200 lumen in high).  No match.  I don't even know how they can both be rated at 200 lumen with that much of a visible difference in both throw and spill.
    d. Streamfire Microlight USB in high mode.  This did better too.

4. Outdoors, low light.
    a. Incandescent G2.  The latter was better hands down.  I could point it between objects and see as well as can be expected.  The M61NL overexposed the nearest objects leaving a black, invisible space between them.
    b. Surefire X200B.  The X200, which I don't believe exceeds 120 lumens, did better, but not by as large of a margin as indoors.
    c. Surefire G2X Pro (older model with 200 lumen in high).  No match.  I don't even know how they can both be rated at 200 lumen with that much of a visible difference in both throw and spill.
    d. Streamfire Microlight USB in high mode.  This did better too.

In summary, perhaps my expectations were too high, but I'm really disappointed with the M61NL.  If the G2X Pro at 200 lumens outperforms it by leaps and bounds, I cannot imagine how much better the new one would do at 600 lumens.  All things considered, I will try the G2X Tactical and if I don't return the M61NLs, it will only be for their longevity and durability for emergency lights to keep in my vehicles.

Thank you, sir.