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Rainier Arms, LLC

Rainier Arms Mountain Series Cold Hammer Forged Barrel 5.56mm NATO

Rainier Arms Mountain Series Cold Hammer Forged Barrel 5.56mm NATO

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Rainier Arms Mountain Series CHF Barrel 5.56mm Nato

Rainier Arms Mountain Series CHF Barrels are built to be of the highest quality, extremely durable and long service life. Cold Hammer Forging of barrels has been known to produce accurate and longest lasting rifle barrels obtainable. The process also creates a defect free bore and the most consistent chamber possible. Many have trusted CHF barrels to be part of their foundation when building their duty rifle.


  • Barrel Material: Chrome Moly Vanadium Steel
  • Made of Mil Spec M249 Machine Gun barrel steel, with heavy M249 Chrome Lining, (appx. 2 times as thick as an M4 or M16)
  • Barrel Type: Cold Hammer Forged
  • Barrel Caliber: 5.56mm NATO Barrel
  • Barrel Length: 14.5 Carbine Gas, 16 Mid Gas, or 18 Rifle Gas
  • Barrel Profile: Modified Mid Weight Government Profile or Government Profile (STD)
  • Twist Rate: 1:7
  • Muzzle Thread: 1/2x28 TPI (Threads Per Inch)
  • Diameter At Gas Block: .750
  • Bore: Chrome Lined
  • Chamber: 5.56mm NATO
  • Made in the USA


  • 14.5 MW - 1 lbs 8.4 oz
  • 14.5 - 1 lbs 9.8 oz
  • 16 MW - 1 lbs 9.8 oz
  • 16 - 1 lbs 11.4 oz
  • 18 MW - 1 lbs 12.4 oz
  • 18 -  1 lbs 13.1 oz


Additional Info

Additional Info

Manufacturer Rainier Arms, LLC
Finish Black
Gas Length No
Caliber 5.56


Customer Reviews (11)

No commentReview by Kevin
- (Posted on 9/7/2016)
No commentReview by Scott
- (Posted on 9/3/2016)
No commentReview by Kristofferson
- (Posted on 8/27/2016)
No commentReview by Vincent
- (Posted on 7/22/2016)
Excellent QualityReview by Eric
I'm very happy with this barrel purchase. Finish is great and quality is outstanding.
Went with the 16" midweight profile and its lighter than anticipated. Have to test accuracy still but the other reviewers seem to be impressed. Don't hesitate on this CHF barrel. Another quality RA product. (Posted on 7/19/2016)
Good quality and price pointReview by James
I bought the 18 in. barrel to build a SPR. The finish on the barrel, threads, and crown have no issues. The fit into my upper receiver was a little tight, but that's not a bad thing. I haven't had any functionality issues with 55 gr, 62 gr, and 75 gr 5.56 ammo. Accuracy is decent, shooting 1.5 inch groups at 100 yards off of my assault pack. Accuracy should improve once the I install the bipod. Overall, I'm impressed with this barrel and will most likely purchase another for an upcoming build. (Posted on 6/29/2016)
Great Barrel, Bad Finish.Review by Nicholas
I bought my barrel a little over two years ago when it still came with an attached gas block. At the time, the barrel was a bit cheaper than it is now, which really made it a steal. I've got nothing but great performance out of the barrel and have thoroughly enjoyed shooting out to 500m with it (which, in my mind, is damn good for a 14.5" barrel).

My only gripe about the barrel is the finish, which I find to be absolutely atrocious. The barrel's finish does not match the color of most other gun parts on the market today. On top of this, the finish is also prone to a light layer of surface rust so it must be oiled often. It doesn't kill the value of the barrel, but it does knock a star off for quality. (Posted on 5/10/2016)
I purchased a 14.5" standard weight barrel and love it! You will not be disappointed! I was in the market for a 14.5 CHF barrel and was on the fence with this one. BCM and DD offer similar barrels but Rainier has never disappointed so I went with them. Great quality, great service, great company! (Posted on 4/7/2016)
Dimes Size Grouping from a Semi-Auto 5.56 here I comeReview by gjohnw
I just installed this barrel in a new SPR system I am putting together. And well the weekend was here and I really wanted to test fire the barrel so, I put the upper on my SBR. For the first time out with a quick Sling Hold Field Zero, she did great.

Rainier Arms Mountain Series Cold Hammer Forged Barrel 5.56mm NATO 18"

Date 08 FEB 2016
Shooting Distance: 100 yards winds 20 mph
62gr Lake City 2.5 inch grouping
75gr Hornady Match 1.5 inch grouping

I cant wait until I put together my lower receiver with a PRS Stock. Then I will spend the time to, Bench Zero the weapon.

Sub MOA from a Semi Automatic 5.56 here I come

(Posted on 2/8/2016)
Great shooter, not too heavyReview by Kirk
I purchased this barrel when they first came out and I love it. 18" rifle gas was pretty uncommon at the time. It has a nice weight/balance and it shoots really well. I use it on my primary run and gun biathlon rifle and although it's not the lightest, it strikes a really good balance for me. No regrets. (Posted on 2/5/2016)
Great ValueReview by Jonathan (CO)
I love this Barrel, I searched and searched for an 18 inch barrel to join the SPR Crew. At the time this barrel was up for grabs I was skeptical because I knew nothing about Rainier Arms quality Barrels. I couldn't find much at all on forums. I knew they are apart of the 3Gun world but so is UTG lol. I went with my gut on this barrel and imglad I did. Mixed with all my Hornady Reloads (55gr SP, 55gr Vmax, 68 gr Match, 70 gr GMX, & 75 gr Match) and a Vortex Vbrite Crossfire 3x9x40, unless I do something wrong, this barrel can't miss. This barrel or the standard weight 18 inch would have been find, I later learned SPR's are normally heavy since precision is key, and the extra weight helps with the barrel heating up. Whatever your obsession may be, this mid weight barrel is awesome. (Posted on 9/20/2015)

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