Building the Ultimate Ultralight, Long Range, Semi-Auto

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Custom Magnesium Roam Rifle Build.
You won’t believe what this rifle weighs!

Ultralight Rifle Build Goal

My goal for this rifle build was to build an ultralight semi-auto long-range rifle that was capable of multiple precision shots out to 1000 yards and weighed less than 7 lbs. Multiple precision shots at 1000 yards isn’t a difficult goal at all in today’s world and there are lots of off-the-shelf $1500 rifles that can do it. However, most of them weigh a lot more than 7lbs or have sacrificed in the barrel department with short pencil profile barrels that aren’t capable of long-range precision. I wanted repeatable precision and excellent ballistics. 

Why 6.5 Creedmoor in an Ultralight Long-Range Rifle?

In this build, I chose to use 6.5 Creedmoor because I felt like it was a good combination of downrange energy, decent velocity, and excellent bullet selection. Heavier bullets than 6mm Creedmoor and better long-range ballistics than a .308. 

It was determined that for long range I needed a 22-inch barrel to push bullets a little faster – something that was going to be difficult to keep weight down as most ultralight builds use 16 or 18 inch barrels, not a 22 incher. 

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I started choosing components carefully and now, after using and shooting the gun since last fall, I’d choose most of them again. 

A Magnesium Rifle

While researching semi-auto ultralight rifles I stumbled across ROAM Rifles, a company specializing in ultralight AR10 platform rifles made from magnesium. 

I was under the mistaken impression that magnesium couldn’t be strong enough to work in AR-style rifles and almost dismissed the idea of trying one out. Curiosity got the better of me and I actually called the company and found out that they were a company neck-deep in aerospace magnesium manufacturing and coating. ROAM Rifle Company was a startup side business. They had/have technology, metallurgy, and coatings never before seen in the firearms industry. 

They assured me that the magnesium they were using was stronger than 6066 aluminum and about 33% lighter! This is not the same magnesium type or process of a certain company that was making magnesium lowers 5-7 years ago and that went out of business. That company was using die-cast magnesium.

Thixomolding and Die Cast Magnesium

There are two types of Magnesium parts. The majority of magnesium parts are made from thixomolding and die casting. Thixomolded and die-cast magnesium parts are what the auto industry uses because it’s a cheap way to make magnesium parts that are lightweight and sufficiently strong as needed for that application. However, they are somewhat brittle.

Extruded and Forged Magnesium

The aerospace industry also uses magnesium parts that are made from high-strength magnesium alloys that are extruded and forged. These are much stronger and are used in almost all helicopters as well as in jets like the F-22 Raptor. These extruded or forged alloys are much more expensive to manufacture and are substantially stronger than traditional die-cast magnesium.

ROAM Rifle’s Magnesium

The magnesium used for the uppers, lowers, handguards, and other magnesium parts used by ROAM Rifles are high-strength magnesium alloys that are forged or extruded. Their primary business is in the aerospace community and they know their stuff when it comes to magnesium alloys and coatings.

I ordered a stripped upper, stripped lower, and handguard. I paid for them personally as this was a personal project. 

When the upper, lower, and handguard arrived I couldn’t believe how much they had in common with feathers. The weight was ridiculously light. I was impressed with everything about them but wasn’t convinced the whole thing wasn’t going to shatter if dropped after being assembled. It was hard to believe that something that light could also be strong.

Building the Ultimate Ultralight, Long Range, Semi-Auto

This was after just missing the opportunity at a wolf by about 1.5 seconds! I made changes to a number of components after this and made it lighter yet.

The ROAM Ultralight Handguard

The handguard, which is 17 inches long and came in FDE Cerakote from ROAM, has only a small section of Picatinny rail in front of the upper receiver and a couple of inches at the end, which was fine for a long-range lightweight build. A couple more grams could probably have been lost by doing a traditional 15-inch length handguard but I liked the extra two inches personally for protecting the +2 gas system and mounting the bipod out further. 

Building the Ultimate Ultralight, Long Range, Semi-Auto

The handguard has M-LOK slots up and down the entire length of the bottom and sides of the handguard. It’s fitted to the upper receiver very tightly and has been sufficiently sturdy. 

Building the Ultimate Ultralight, Long Range, Semi-Auto

One thing to note about the handguard is that ROAM has since changed the design slightly to an improved version and this handguard pictured is no longer available. 

Building the Ultimate Ultralight, Long Range, Semi-Auto
The ROAM 17-inch magnesium handguard weighs just 8.9 ounces!
Building the Ultimate Ultralight, Long Range, Semi-Auto
For weight comparison purposes only, this is one of my personal favorite rifle manufacturer’s (Seekins) AR10 handguards without a barrel nut and only 15 inches long.

Handguard Weight: 8.9 Ounces

Price: $299

ROAM Handguard

ROAM R10 Ultralight Upper Receiver

There are two options for upper receivers at ROAM. The first option is without a forward assist and the second option includes one. The slick-sided one is a few dollars less and is lighter in weight.  I chose the one with forward assist as I wanted to be able to close the bolt quietly in hunting situations if the need arose.

Building the Ultimate Ultralight, Long Range, Semi-Auto
Assembled ROAM Upper Receiver with a steel forward assist that I replace later for a lighter aluminum one. Also, note the glass-filled polymer dust cover and brass deflector.
Building the Ultimate Ultralight, Long Range, Semi-Auto
Completely stripped standard aluminum AR10 upper receiver for weight comparison purposes.

ROAM Upper Receiver Weight: 8.4 oz

Price: $ 279.95

ROAM R10 Upper Reciever

ROAM R10 Ultralight Lower Receiver

Building the Ultimate Ultralight, Long Range, Semi-Auto
The Roam R10 Lower Receiver.

Don’t really know what to say about this except it’s really lightweight. It has nice lines that match well with the upper receiver.

Building the Ultimate Ultralight, Long Range, Semi-Auto

R10 Lower Weight: 7.2 oz

Price: 299.95

R10 Lower Receiver

6.5 Creedmoor Barrel by ODIN Works

I called and told ODIN Works what I was trying to do as I’ve had excellent luck with their barrels in the past and they did a custom contour for me that knocked some weight off of their stainless match 22 inch 6.5 Creedmoor barrel. We certainly could have taken more metal off but I wanted a shooter. This barrel features a rifle length +2 inch gas port. In other words, the gas port is 2 inches longer than a standard rifle-length gas port, which is great for higher pressures and use with a suppressor.

Building the Ultimate Ultralight, Long Range, Semi-Auto
The ODIN Barrel getting weighed.

Specifications of the ODIN Works Barrel

  • Profile: Tactical Match
  • Length: 22″
  • Gas Placement: XL Rifle
  • Weight: 3.38 lbs (2 lbs 12.2 oz after contouring)
  • 1:8 twist button rifle
  • Made from 416R Stainless Steel
  • Hand-Lapped
  • M4 Feed ramps
  • 5/8-24 Threading
  • 1″ MOA guaranteed
  • Includes XL Rifle gas tube

ODIN Works Barrel after contouring – Weight: 2lbs 12.2 oz

Price: $440 (includes gas block and +2 gas tube)

ODIN Works 6.5 Creedmoor | 22″ Tactical Match +2″ XL Rifle | Barrel

I also painted the barrel using Brownells Aluma Hyde II spray paint and have been very happy with the results simply air/sun drying it.

JP Rifles Bolt

JP Rifles makes great stuff and their low-mass bolt carrier is no exception. At some point, I may switch for a carrier with forward assist notches. I used their smaller firing pin hole to handle higher pressures (JP refers to this as their EnhancedBolt). I already had a low mass bolt carrier from a previous 308 build and simply added the EnhancedBolt head.

Building the Ultimate Ultralight, Long Range, Semi-Auto

Weight: 14.4 oz

Price: $485 (complete bolt carrier group)

JP Large Frame LMOS Carrier Group with JP EnhancedBolt

Triggertech Adjustable Trigger

I had a Triggertech Diamond Adjustable trigger on the shelf already and for a precision build it made sense to use. I’ve become a much bigger fan of flat triggers as it allows you to put your finger at the bottom and use leverage to decrease the trigger pull. The trigger is adjustable from 1.5-4 pounds. I installed the AR-15 version of the trigger and Triggertech makes the same trigger in an AR10 version, which I would’ve used if I’d had one. I have had no issues using the AR15 version. I’ll link the AR10 version below. These triggers feature what Tiggertech refers to as Frictionless Release Technology, and in my opinion, they’re one of the best and most robust triggers for precision applications.

Building the Ultimate Ultralight, Long Range, Semi-Auto

Weight: 2.2 oz

Price: 314.99

TriggerTech AR10 Diamond Trigger

V Seven Castle Nut and Endplate

Trying to cut every possible ounce, I chose to use an aluminum castle nut and endplate from V Seven. The castle nut weighed 6 grams and the endplate weighed 4 grams.

Building the Ultimate Ultralight, Long Range, Semi-Auto

I installed these later after having previously installed the steel versions. The steel versions together weighed 30 grams. I’ve had zero issues with them and would use them again. I don’t use the QD in the endplate but it’s there if needed.

Building the Ultimate Ultralight, Long Range, Semi-Auto
10 grams together.

Castle Nut Weight: 6 grams
Endplate Weight: 4 grams

Price: $63

V Seven Ultra-Light Endplate Castle Nut Combo Pack

V Seven Ultralight Takedown Pins

I originally installed steel takedown pins and switched them out for these V Seven ultra-light aluminum takedown pins. Hundreds of rounds later they have worked great with no discernable wear. The steel takedown pins that I replaced them with weighed 21 grams.

Building the Ultimate Ultralight, Long Range, Semi-Auto

Weight: 7 grams

Price: $34

V Seven Ultralight Takedown Pins

Forward Assist

The original forward assist that came installed from ROAM was steel and weighed 22 grams. I found that Strike Industries makes a lightweight version out of aluminum with a steel pawl and it weighed just 11 grams.

Building the Ultimate Ultralight, Long Range, Semi-Auto
Strike Industries forward assist
Building the Ultimate Ultralight, Long Range, Semi-Auto

Weight: 11 grams

Price: $19.95

Strike Industries Lightweight Forward Assist Assembly

KynSHOT RB5004 “Shorty” Recoil Buffer

The KynSHOT Shorty Recoil Buffer is advertised as reducing felt recoil 20-30%. While I have no way of measuring that number, I can tell you that this rifle shoots smooth and the recoil is extremely mild. It’s honestly not much more than an AR15 shooting 556. This buffer is specifically for AR-10s using a 7.0-inch collapsible buffer tube. The buffer is hydraulic but will work at temperatures down to -30F.

For comparison purposes most of the heavier AR10 buffers that you would use in a suppressed 6.5 Creedmoor weigh between 4.5-5.5 oz.

Building the Ultimate Ultralight, Long Range, Semi-Auto

Weight: 3.7 oz

Price: $129

KynSHOT Precision .308 Shorty Carbine Recoil Damper – 2.5″

Superlative Arms .750 Titanium Adjustable Clamp-on Gas Block

Building the Ultimate Ultralight, Long Range, Semi-Auto

If you’re going to suppress your AR style rifle, the Superlative Arms Adjustable “bleed off” gas block is the best there is. When adjusted correctly it allows gas to bleed off out the front of the gas block rather than pressurize your gun and send gas back into the system.

Building the Ultimate Ultralight, Long Range, Semi-Auto

The benefits of an adjustable gas block, especially suppressed, are huge for reducing wear, over-gassing, felt recoil, reduced bolt speed, faster follow-up shots, increased reliability, and overall wear and tear.

All adjustable gas blocks will give those benefits but the Superlative Arms gas block does it a little differently. Imagine water in a hose. No adjustment in the gas block means that all of the water that fits in the hose goes through the hose. A standard gas block is simply a restriction in the hose to “hold back” some of the water. The Superlative Arms gas block creates a Y. The extra water/gas not needed is allowed to escape out the front. You can adjust how much or how little that happens with the detented screw. The gas block itself never seizes or carbons up and you don’t get erosion because of the design.

Building the Ultimate Ultralight, Long Range, Semi-Auto

I wanted the clamp-on style so as not to add a pressure point in the barrel with set screws. Titanium was the preferred material because it was lighter than steel. Superlative Arms does make a steel version as well which is less money.

Weight: 1.07 oz

Price: 209.99

.750″ Titanium Adjustable Gas Block, Bleed Off – Clamp On – Dark DLC Finish

Future Forged Vector-5 Precision Rifle Grip

Building the Ultimate Ultralight, Long Range, Semi-Auto
Future Forged Vector 5 Lightweight Grip in FDE

I had never heard of Future Forged prior to starting this rifle build. I actually called and talked to the owner and he was very knowledgeable and has some really crazy great tech that he can do with grips. Like, he can create a custom grip specific for your hand.

In this case, I wanted a lightweight precision (more vertical) grip with a thumbshelf on the right side of the grip. At the time, that was only available in a prototype. It’s now a full-production model called the Vector 5.

Building the Ultimate Ultralight, Long Range, Semi-Auto
The thumb shelf.

The Future Forged grips are made from carbon fiber reinforced polymer and are designed for ergonomics, comfort, and for ideal trigger finger placement.

I couldn’t be happier with how the Vector 5 has performed. It’s insanely lightweight and it’s very comfortable and strong. I’d buy it again in a heartbeat.

Future Forged also has a hollow titanium screw that weighs almost nothing for attaching the grip to the rifle.

The Vector 5 grip weighs almost 1 oz less than a standard plastic cheapo AR-15 grip and almost 2 oz less than the ERGO grip it replaced.

There are multiple colors, styles, shapes, and custom offerings from Future Forged. Future Forged offers a lifetime guarantee.

Building the Ultimate Ultralight, Long Range, Semi-Auto
The Future Forged titanium grip screw is hollow
Building the Ultimate Ultralight, Long Range, Semi-Auto
Weighs 1 gram.

Weight of Vector 5: 2 oz

Price: 94.99

Future Forged Vektor-5 Precision Rifle Grip

Building the Ultimate Ultralight, Long Range, Semi-Auto
Mission First Tactical BATTLELINK Minimalist Stock in FDE

One of the most overlooked AR style stocks in the world is the Mission First Tactical BATTLELINK Minimalist Stock. It’s one of the lightest, weighing only 5.8 ounces. It has actual rubber on the buttstock, QD mount, is fully adjustable, and is one of the few stocks that doesn’t pull my beard hairs. It’s also priced very competitively with everything else out there.

Weight: 5.8 oz

Price: 59.99

Mission First Tactical BATTLELINK Minimalist Stock

Presma AR-10 Charging Handle

Building the Ultimate Ultralight, Long Range, Semi-Auto

I really cheaped out on the charging handle. It’s fully ambi. Lightweight and cheap.

I bought it at AR-15 Discounts and so far have no complaints. I didn’t like the other options available for one reason or another.

Price: $24.95

Radian Weapons Talon Safety Selector

The Radian Talon 45/90 safety selector was chosen because of three reasons, I love 45 degree safety’s, wanted it to be ambi, and it’s very lightweight. I weighed a Battle Arms Development Safety and it weighed 21 grams compared to the Radian at 14 grams. I also ground down the right side to better fit with my grip.

Building the Ultimate Ultralight, Long Range, Semi-Auto
Building the Ultimate Ultralight, Long Range, Semi-Auto
Building the Ultimate Ultralight, Long Range, Semi-Auto

Weight: 14 grams

Price: $59.95

Radian Weapons Talon Safety Selector

Magazine Release System

At some point several years ago I bought an aluminum magazine release system from China through AliExpress. I can’t find it now so you won’t get a link but it cost something like $3 shipped and it weighs 5 grams. It’s held up great with no issues. The steel version which I replaced weighed 14 grams.

Building the Ultimate Ultralight, Long Range, Semi-Auto
The cheap aluminum mag release system.

AB Suppressor Raptor

Building the Ultimate Ultralight, Long Range, Semi-Auto

Having played with and shot many of the suppressors available in the industry, I chose a lightweight AB Suppressor Raptor. When you look at the pictures it’s easy to assume that it’s huge. What you don’t see is that it actually goes back over the barrel and creates more volume and reduces back pressure by having a huge initial first blast chamber.

Building the Ultimate Ultralight, Long Range, Semi-Auto
The Raptor 6 is only 5.5 inches long. The Reflex that goes back over the barrel gives the illusion of a larger suppressor. In this photo, the Raptor is lined up to show where the barrel sits when the suppressor is installed.

It’s also made out of titanium and is very light. The part that goes over the barrel is called the Reflex and you have the option of taking it off if you want to lighten things even further. I felt like the reduced backpressure and extra volume were worth the couple of ounces it cost me. With the reflex installed, the tone is deeper or lower.

I’ve been very happy with the Raptor 6 and have shot multiple coyotes on one stand with it. The tone is great, I notice no gas in my face and because some of the weight is over the barrel the gun balances better.

Building the Ultimate Ultralight, Long Range, Semi-Auto

Pictured is the Raptor 6 with a 6.5 Endcap and the 3 inch Reflex. Together they weigh just 11.6 ounces.

Weight: Just Suppressor 7.1 oz. Reflex 4.4 –Together 11.6

Price: $780

AB Suppressor Raptor

Other Notable Parts or Accessories

Leupold Mark 6 3-18

Seekins Precision MXM Scope Mount 34MM 1.45″ 20 MOA

Lancer Systems L7AWM® 10 MAGAZINE – This magazine needs to be tuned by cutting a coil. Directions on Lancers site.

Hatch Outwest Bipod

Really Right Stuff TFCT MK2 Tripod 33 w/ Anvil-30 ARC Head


I shot both Hornady factory ammunition and handloads. The factory ammunition all shot minute of angle or better but all I have in factory ammo are 140 grain or heavier. I wanted to shoot the 123 grain and push them faster.

Building the Ultimate Ultralight, Long Range, Semi-Auto
Example of velocity with 140 grain bullets.

I ended up settling on a handloaded 123 grain Hornady ELDM load with a velocity of 2934.

Building the Ultimate Ultralight, Long Range, Semi-Auto
Six shot rapid fire group with the 123g ELDM.
Building the Ultimate Ultralight, Long Range, Semi-Auto
3 shot slow fire group with the 123g Hornady ELDM going 2934 fps.

Overall, I’m very satisfied with the accuracy of the gun and the ammo. The 123 grain load outperforms the 140 grain load beyond 1000 yards in drop and matches it in wind to 1000 due to the higher velocity.

Total Weight of the Ultralight Semi-Auto Long-Range Rifle

When I first put the rifle together, all of the lightweight parts hadn’t shown up yet and it weighed in at 6lbs 15.9 oz. That was no magazine, no suppressor, and no optic or optic mount.

I changed out the castle nut and endplate, the entire magazine release system, the forward assist, takedown pins, and the grip, and ended up with a total weight of 6.75 lbs or 6lbs 12 ounces. I lost 3.9 ounces by making those changes.

6.75 pounds rivals the lightest weight AR10s on the planet that are small frame, carbon fiber, pencil-thin 16 inch barrels, with short handguards, non-adjustable gas blocks, milspec triggers, etc.

Building the Ultimate Ultralight, Long Range, Semi-Auto

I also want to point out that had my goal been to get down towards 4.5 lbs I think I could have done it pretty easily by using a lighter profile barrel, lighter stock, lighter buffer, non-adjustable gas block, shorter handguard, mil spec trigger, no forward assist on the upper, no ambi safety, smaller grip, etc. I wanted an ultralight Semi-Auto Long Range capable rifle and I built one.

The rifle as built is fully capable of hitting clay pigeons out to 1000 yards.

Let me know in the comments if you’d ever build something like this and tell us what components or parts you’d use.

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