Building a Fighting Rifle

The three accessories that every fighting rifle should have and what I chose for my build.

Written by rtfjr86
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From what I gather from all of my research, there are three necessary accessories to turn your AR-15 into a "fighting rifle". For me personally, that means making the rifle more useful and easier to use in situations that I may actually find myself in. Namely, home defense and civil unrest. Those necessary items are 1: a weapon mounted light, 2: a red dot optic, and 3: a sling. In this article, I’d like to share with you what products I added to my rifle and my reasoning behind my product decisions.

Check out the upper build here.
Check out the lower build here.

Parts List

  • Sig Sauer Romeo 5 - $160
  • T.Rex Arms Sling - $60
  • Fenix PD35 V2.0 flashlight - $60
  • Fenix AER-02 V2 pressure switch - $20
  • Fenix ALG-05 pressure switch mount - $15
  • Fenix ARBL18 18650 battery - $26
  • ODIN Works 1" M-LOK Flashlight Mount - $38

1. A Weapon Light

The first thing I added to my rifle was a weapon light. A light is a necessity because most violent crimes happen at night and since we are the good guys, we can’t shoot what we can’t see. I went with the Fenix PD35 v2.0. I have several Fenix lights that I alternate through as EDC lights and they have yet to fail me. The consensus among folks that shoot a lot more than me is that Surefire seems to make the best weapon lights. However they are just too far out of my price range. I also really like the Streamlight Protac HL-X which seems to be the default for almost everyone not running a Surefire. One thing that kind of turned me off of the Streamlight was the fact that the light is IPX7 water resistant with the tail cap but only IPX4 rated with the pressure switch. The Fenix is IP68 rated with or without the pressure switch. Water resistance is not hugely important to me, but it is something that I noticed. Another reason I went with the Fenix is the price. Out the door with shipping, I paid $104 for the light, pressure switch, pressure switch mount, and a rechargeable 18650 battery. The streamlight with the Cloud Defensive pressure pad mount and rechargeable battery is about $200. Finally, the last reason I chose the Fenix is because I want to try something different than what is mainstream. Fenix products also come with  a lifetime warranty, so no worries there.

I wanted a mount for the light that would keep the light close to the rail so that the light wouldn’t be bumping into everything and getting snagged on stuff. Fenix offers their own mounts, but I don’t like how far they hold the light off the rail. Plus, their mounts are picatinny only and my rail only has M-LOK slots. That means I would have to attach a piece of pic rail to the handguard and then the light mount which would push the light out really far. The Odin Works M-LOK FLM 1" mount is exactly what I was looking for. It directly mounts to the M-LOK rail and also holds the light extremely close. So close in fact that when I tried to mount the light in the 1 o’clock position, the mount would hit my iron sights. I ended up mounting my light in the 5 o’clock position. I also had to wrap the light with a few layers of gorilla tape in order to get the light really secure in the mount because the body of the light is just under 1" diameter of the mount.

Finally, the mount for the pressure switch is mostly great. It holds the pressure pad very securely in place without the “need” for velcro or zip ties. Hower, even though the mount is not going to come off, it does have a slight rattle to it when activating the pressure switch. So I threw some zip ties over it anyway and now it is silent and rock solid. The other quibble I have about the mount is that it is relatively thick, which means the pressure switch sits high above the rail. This means that when I use the pressure switch, my thumb comes into view through my optic and obscures the field of view a little bit. Not a huge deal, but other pressure pad mounts like the Cloud Defensive are much lower. This issue can easily be overcome with a higher optic mount, like a lower ⅓ co-witness mount. The mount that came with my optic has an absolute co-witness height.


Fenix PD35 V2.0 in ODIN Works Mount


Fenix Pressure Switch and Mount


2. An Optic

The next thing I added to my rifle was red dot optic. It is much faster and easier to put a dot on a target than to try to line up two sights with the target, particularly under stress. I was looking for something that had a lot of really good reviews, but would not break the bank. I narrowed my choices down to the Vortex Crossfire, Holosun HS403B, and the Sig Sauer Romeo 5. I ended up going with the Romeo 5, which is almost identical to the Holosun. Actually, the Romeo 5 is made by Holosun. The only difference is that the battery compartment on the Holosun is held in place with tiny screws whereas the Romeo 5’s battery compartment is under a cap that can be opened by hand. I didn’t want to be worried about having a tiny screwdriver on hand or worse yet, stripping out the screws or their sockets. I also like the Sig over the Vortex for its motion activation feature which shuts the optic off when not in use but then immediately turns it back on with slightest movement. This really helps to save battery life. Finally, the Sig has ½ MOA adjustments while the Vortex only has 1 MOA adjustments. Theoretically, I should be able to get a more accurate zero with the Sig.


Sig Sauer Romeo 5 Red Dot Optic


Sig Sauer Romeo 5 Right Side


3. A Sling

The last thing I added to my rifle is a Sling. A sling provides many functions. In my opinion, the most important reason for a sling is being able to go hands free while maintaining retention of the firearm. I do not want to have to set my weapon down to be able to draw a side arm or use my hands for anything. From what I gather, there are a vast number of good rifles slings out there. I narrowed my options down to the Ferro Concepts Slingster and the T.Rex Arms sling. I went with the T.Rex Arms sling because, for starters, they were in stock. Trying to buy anything gun related in an election year is an exercise in frustration. I also liked it over the Slingster because the Slingster has a spring loaded adjustment strap that could fail over time. The T.Rex Arms sling uses a simple tri-glide clip for tension adjustment. Also, I read that the metal pieces of the Ferro have been known to scuff receivers. Not a huge deal since guns are just tools to be used, but it’s not an issue at all with the T.Rex Arms sling because all of the tri-glides are plastic. As an added bonus, the T.Rex Arms sling comes with two bungees that can be used to stow the sling neatly when not in use. Finally, the T.Rex Arms sling in coyote brown just looks amazing, especially with the black stripes on the padded section. I ordered my quick detach (QD) swivel mounts and QD endplate from Bravo Company USA.


T.Rex Arms Sling Stored With Bungee


BCM QD Endplate



I now have what I feel is a fighting rifle. I’m ready for home defense and any training classes that I decide to take. I can’t wait to really put the gun through its paces to see how it holds up and find out what I can do to tweak and improve my setup. At this point, I’m saving my pennies for ammo, training, and a plate carrier. What do you think about my setup? Let me know in the comments. God bless.

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