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Benelli M4 -- Weapon light mounting Options Suck!


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Okay, as many of you know, I've tried pretty much every option out there to get a decent weapon light mounting solution. For the past few years, I've settled for running a Surefire M600c Scout Light on a Surefire M80 rail. I used a GearSector offset mount to put the light in a decent location. While this works, there are several significant points I dislike;


1. Weight. The M80, rail covers and the GearSector mount add approximately eight ounces of weight over the factory forearm.

2. Comfort. Even with low profile LaRue Index Clips, the thing is the size of a one liter soda. The factory forearm is perfect.

3. Barrel Shadow. The current setup sits too far to the rear.


Now, I can fix problem 3 mostly by dumping the GearSector mount and moving to a Thorn Tail. This would push the light forward off of the handguard and would be much more comfortable.


However, problems 1 and 2 are my primary concerns. I've tried the Blam4, and couldn't make it stable enough for rough use. I refuse to use barrel/mag clamps that require tools to disassemble the weapon. I've tried the SideArmor rail, it's a fail.


So I've come to the conclusion that I'm going to have to make something myself. I just ordered a set of FFT reproduction handguards to chop up. Next, I ordered this mount:



this is a Mount-n-Slot SMC mount made to attach to a Magpul MOE handguard. My plan is to modify the FFT left side forearm to fit this mount. I plan to mount the attachment point of the mount just ahead of where the piston sits. I'm going to have to get creative and remove some material from the forearm so the mount will hold the light parallel to the barrel. If you look at your forearm, this area is angled inward towards the barrel. Countersinking the base of the mount will also reduce sharp edges to catch my thumb on during recoil. I may use some sort of black epoxy to seat the mount to the forearm.


I may need to 'fine tune' the mount in a vice with a hammer to change the angle of the dangle.


I may need to source some longer fasteners due to the thickness of the forearm.


I believe the forearm is plenty strong enough to support the weapon light. They are significantly thicker and better supported than the ar15 plastic handguards.


If this works as I hope, I should be able to address all three of my outlined issues.



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I like the look of the Gear sector mount. Now to find something comparable to the Streamlight TLR2s that uses a 18650 rechargeable battery, offers 600+ lumens and a laser that carries like the Crimson trace. I know we won't be looking at 200yd targets so why have a light/laser carry that far? Because we can.

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I received my FFT forearm yesterday. Still waiting on the mount though. I did some testing and came up with a better game plan. I'm going to fill in the handguard with epoxy ahead of the left piston. Once it dries, I'm going to carve the inside face of the forearm out to allow the mount to seat flush. Only the mount's arms will be visible as they protrude out if the top of the forearm. I'll cut the mount some if needed to relieve the area up against the barrel.


The hardest part will be making the fasteners work. I'll need longer screws and maybe a washer on the outside of the forearm to spread the load bearing surface. I might cut a countersink into the forearm for the washers depending on how much material I have.


I'll probably epoxy everything into place afterwards for an added level of stability. I figure the forearm will be chopped up, no real need to have it serviceable.


I have some experience carving plastic and milling aluminum. I think if I take my time, this will end up being the perfect weapon light mount, balancing weight and comfort issues.


I'll take pictures along the way so others can copy the install if they so choose.

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Check out my post here for a recent review on the BLAM4 mount. It works perfectly for me with no movement whatsoever. I don't know if I got lucky and received a mount that was machined perfectly for my M4, or if some changes have been made to address the movement issue described in the OP. Either way, I'm very pleased with the purchase.

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Alright... Parts came in on Wednesday. What a pain in the ass this was. It took me seven hours of filing, grinding, bending, gluing, drilling, praying, cussing, bleeding and so forth; but it is done, and it works! I nearly gave up at least half a dozen times. There is so much interference fitting going on in the inside of the forend, it isn't even funny. I had to reprofile the entire bottom of the mount with a ******* file to get as much clearance as I could get around the magazine tube and the ARGO.


I had to use a three pound sledge and my vice to tweak the angle of the mount to align it with the barrel and to get the clearance I needed. Basically, I hammered the mount over about 30 degrees to the left, then tweaked the angled of the mounting arm.


As expected, the mounting fasteners were an epic pain in the ass. If you cranked the fasteners down too much, it would deform the forend and cause them to bow away from the barrel. So I had to go with a lesser amount of torque, red locktite on the fasteners, then I epoxied the entire assembly together to prevent anything from backing out.


If someone said they'd give me 200 dollars to do a set for them, I'd turn it down. It's that big of a pain in the ass.


The sling mount worked out well. That was the first thing I tackled, and I only swore at the little lock ring that holes the device in place. I really like how flush mounted it is. I think anyone could install it without much risk of junking their forend. There are few places within the forend that have the clearance to install the sling mount unfortunately.


Overall, I'm mostly pleased with the way it turned out. The fasteners on the outside are ugly, but I don't care. It dumped half a pound of weight off my M4. The light activation button is in the perfect spot. Barrel shadowing is about the same as what I had with the M80 rail.


I'm not sure about the strength of the mount I made. I think a solid blow might knock the handguard off. The length of the light leverages against the forend. When squeezing the front of the light towards the barrel hard, it pushes inward, and you can see the forend bend in the middle and flex. That was before I sealed everything in epoxy, so hopefully that will add to some rigidity.


The light is certainly low profile. The way I bent the mount pretty much tucked it flush with the barrel.


If I was doing it again, I'd probably just live with the mount being on the outside of the forend. I'd then bend the mount to adjust for the inward angle. The mount bends pretty easy with a vice and three pivot points of force.


I'm glad it's done, I never want to do that again!





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Here's all the assembled crap. Freedom Fighter Tactical OEM Reproduction handguards. Impact Weapons Components SMC Scout Light Mount, MOE Carbine 4 slot top model. QD Micro Flush Sling Mount.



Find the location inside the handguard that has enough clearance to not interfere with the magazine tube or the pistons. Once you've found your location, use a sharp punch to mark a center.

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