Bloodline 16” M4 5.56 NATO (Mid-Length)

From: $176.00

16″ M4 5.56 NATO Bloodline Barrel (Mid-Length): This 16″ M4 5.56 NATO Mid-Length barrel was designed around the USASOC specs for an Improved Upper Receiver Group with a little bit of the Rosco touch as well. The longer gas system allows for a smoother gas curve which leads to managed dwell times. This combo creates a great balance of speed and performance.

(29 customer reviews)

Melonite Gas Tubes

Our Rosco Melonite Gas Tubes have an extremely durable Black Nitride finish that increases corrosion resistance, wear resistance, fatigue strength and cosmetic appeal. These gas tubes work great under a handguard because they are more durable than standard gas tubes. Available in pistol, carbine, patrol length, mid-length, and rifle lengths. Does not include a roll pin.

Non-Adjustable Gas Block, v2

Our v2 Non-Adjustable Gas Blocks feature the same 'Bloodline' dependability, with improvements for the modern shooter.  We added a knockout hole at the front of the gas block to aide in removing the gas tube. Also featuring improved tolerances and finishes, making the v2 Gas Block a staple for years to come.

Adjustable Gas Block

Our Rosco Adjustable Gas Block is purposely designed to be lined up perfectly with our barrels and gas ports to ensure reliable cycling every time. These Adjustable gas blocks pick up where our standard block leaves off and works perfectly for shooters that want to be able to control their gas flow for suppressed applications.

Out of stock

In stock

16″ M4 5.56 NATO Mid-Length Bloodline Barrel (Mid-Length): This 16″ M4 5.56 NATO Mid-Length barrel was designed around the USASOC specs for an Improved Upper Receiver Group with a little bit of the Rosco touch as well. The longer gas system allows for a smoother gas curve which leads to managed dwell times. This combo creates a great balance of speed and performance.

Our Rosco 5.56 (NATO) barrels are designed to meet the modern day carbine shooters requirements. We are a long way from our daddy’s “Sporter” AR, and those specs just won’t cut it anymore. From properly managed dwell times for SBR’s, to running Suppressed, or setting up a balanced patrol carbine we have incorporated your needs into our engineering. We have successfully accomplished this by picking the right twist rates, gas port diameters, and barrel materials according to the barrel we are making (not a lazy blanket method). We have also balanced input from our consumers and military end users in order to bring you the product you need, not just the one we want to sell you.

Barrel Length 16″
Barrel Weight 28.97oz
Barrel Material 4150 CMV
Barrel Caliber 5.56
Barrel Profile




Barrel Thread

1/2 x 28

Gas Block Size


Gas System Length

Barrel Crown

11 Degree

Barrel Finish


Barrel Extension Finish



Browse all of our 5.56 NATO Bloodline Barrels >>

Additional information

Weight 2.0 lbs
Dimensions 19.5 × 2.3 × 2.2 in

Melonite Gas Tubes


Mid Length

29 reviews for Bloodline 16” M4 5.56 NATO (Mid-Length)

  1. Enrique Olivarez (verified owner)

    I built my first AR this weekend with this barrel and I did extensive research before making my purchase. I wanted everything to go smoothly. Everything I read and everything everyone else was saying proved to be true and more. The craftsmanship of the Rosco product comes 2nd to none! I also appreciated the dimple on the bottom of the barrel for the gas block to stay put. I was worried about making that dimple myself. I also purchased the gas block and tube from Rosco and everything lined up perfectly making that part if my build almost effortless. Shipping was fast and customer service was on point when I had questions. I already have a 300 blackout in the works and I was so impressed with my order that I’m not even thinking of trying any other brand. Thanks for making me feel like my investment was well worth every penny spent. I appreciate the guys at Rosco for helping me make my first build a reality!

  2. Stephen F Koch (verified owner)

    Did a lot of research before buying the barrel and BCG from ROSCO for my recent build. I could’t be happier. The fit and finish is 4.0. Shipping was quick once the barrel was manufactured. All parts were delivered on time. The installation was EASY! Everything I needed was provided. Added the Rosco adjustable Gas Block and Rifle length gas tube to finish it off. Attached everything to my Colt Upper receiver and Lower. Everything matched up perfectly.
    Took it out to my farm to sight it in. After about 5 shots, rifle was on.
    engaged 100 Yard targets with federal 55 gr FMJBT with .50 MOA average. Shot standing, off hand, steel targets at 450 yards. Hit 10 of 10.
    This is the most accurate rifle I have ever owned, and I have been shooting for over 30 years.
    Great product and great people.
    Oh yeah, I also received a Military discount to boot. Get Some!

  3. Bob Searfoss

    Barrel and bcg were part of an ar build from different manufactures at LFOD 2018, couldn’t be happier with the way it performs

  4. Dalan Speth (verified owner)

    I recently purchased the Bloodline 16″ M4 and I couldn’t be happier with it’s performance, looks, weight. Its the full package. I strongly recommend ROSCO to anyone looking for quality products.

  5. emceekyn (verified owner)

    Rosco is quickly becoming my go-to destination for the products they offer. The shorty PB-137-GVT-223W-8-M runs flawlessly and I expect even better velocities and accuracy with the 16″. Very well built components, considerations made for weight, value, and community feedback. Great vibe all around. Now start making some .308 barrels! You guys are repping what it’s about. Carry on.

  6. Troy (verified owner)

    After extensive research, I have found that ROSCO’S barrel was the absolute best bang for the buck! You can definitely get lost in the world of AR15 barrels, but this site made my decision that much easier with straight forward and honest info. It also helped by not having to flip my wallet inside out for a quality barrel! Installation was a breeze and after a couple of rounds the red dot was spot on and finished out the first day with the new barrel with around 500 rounds! It works flawlessly and I would recommend this to anyone looking to upgrade their barrel! ROSCO has my business from here on out! Thanks for providing a good quality barrel for a great price! Keep up the good work!!

  7. Shawn (verified owner)

    I bought this barrel this time to replace a barrel on one of my guns. As all of my other bloodline barrels have been, it is pristine. Machining is great, the finish is great, and of course it is gassed just right. I have many Rosco barres and recommend them constantly. I can’t get enough!

  8. Tonyc

    Purchased this barrel from PA. And it is the sweetest barrel I own, it impressed me so much I just purchased another. ROSCO barrels are my go to barrels. Thanks

  9. Calvin (verified owner)

    Love my new pure breed barrel. I ordered another for my new rifle build. The guys @roscomfg are the best.

  10. Calvin (verified owner)

    I love the pure breed barrel. I ordered another for my next build. The guys @roscomfg are the best.

  11. Tarek M Islam

    This barrel is absolutely phenomenal. I started off small with my rifle. In the beginning I had an Anderson barrel (which wasn’t bad!) The Anderson served me well going several thousand rounds. But when it came time to upgrade and get serious, I was faced with $200 -$300 barrels that promised amazing accuracy. Because of this, I stuck out with my Anderson barrel until I heard about Rosco. I was skeptical still as to how a $150 barrel will perform the same as a $300 barrel. Now I’m not a 1MOA shooter. But the night and day difference was undeniable. This $150 barrel was on par or outperforming some high dollar barrels my friends were running. Granted, shooter skills vary, but the barrel absolutely is the reason behind my newfound accuracy. I will never not buy Rosco from now on.

  12. Calvin (verified owner)

    I love this so much that I ordered a second barrel for my second Aero Precision built. I highly recommend this barrel.

  13. gwilliams7 (verified owner)

    This barrel is absolutely gorgeous! It is apparent that Rosco and their employees take great care and pride in making their product. It is extremely refreshing in this day in age to receive something so beautifully crafted. I am a military veteran of nearly 30 years and have been around weapons all my life and I have never seen such excellent machining and finish work all in one product. I spend my time now building weapons for my self and others and I will most certainly be back for more barrels from Rosco. Please do not hesitate to purchase one of these barrels… will be truly amazed at the quality workmanship you are getting. It will put a smile on your face and that’s a good thing!

  14. Doug Dunlow (verified owner)

    Rosco manufacturing has made an outstanding barrel!
    The simple for the gas block makes for an easy alignment.
    Fantastic barrel! Keep up the great work. I will be spreading the word about these barrels

  15. Doug Dunlow (verified owner)

    Rosco manufacturing has made an outstanding barrel!
    The dimple for the gas block makes for an easy alignment.
    Fantastic barrel! Keep up the great work. I will be spreading the word about these barrels

  16. Philip Dicke Sr (verified owner)

    Bought this after watching the SOTAT review of one of your barrels that went 27,000 plus rounnds and only was beginning to loose some accuracy due to some muzzle erosion.. the chamber, feed ramps and bore along with the gas port was still well within spec……. Thats phenomenal !
    I will. never put that many rounds thru
    this build unless we really need to take this country back !!!!!! Hope it never comes to that …..
    Gas block and tube will jusy be a bonus .
    Thanks for the excellent customer service and shipping times !!!!!

  17. Dave Smith (verified owner)

    Have not shot the new build yet. I am very happy with the quality and craftsmanship of the barrel. Shipping was quick , expect good things out of this barrel.

  18. John (verified owner)

    I’ve not made it to the Range yet and I went into this purchase doing some preliminary research on the Barrel to begin with so I do have some expectations “BUT” if I am to expect the quality to be anything remotely close to the quality log service and the packaging I’m certain I will be thrilled with the quality and performance.
    They shipped my Barrel & Gas Tube immediately and both items were individually packaged, and I was impressed with the packaging as well they were both in protective display quality packages and. 100% safe from anything the shipping company could’ve done during the trip to my front door. So I have great expectations but am extremely happy to this point

  19. Mark (verified owner)

    This is my 2nd barrel order and once again, very pleased. Received my order in a timely manner and nicely sealed packaging keeps my confidence high in the Rosco Manufacturing team. Thanks again!

  20. Cesar Legaspi (verified owner)

    Perfect! You guys made an excellent barrels as I expected.

  21. Dave W

    Barrel is good, adjustable gas block that costs more than the barrel is concerning

  22. S.C Fraser

    Great selection, fast shipping. Thank you Rosco Mfg!!!

  23. Philip Cotton (verified owner)

    Solid barrel @ affordable price so I’ve found.
    Ended up going with Rosco fixed gasblock & gas tube as well.
    End result has been 3 – 4 o’clock ejection with number of loads 1.5 groupings @ 100 yards = money well spent.

  24. Jose Hernandez (verified owner)

    Great price and even better quality.

  25. Szelas73

    This a second one I owe. Read others reviews! Quality is superior and on the par with more expensive ones. I’m super happy 100% recommend this company to others. Don’t hesitate to pull trigger with this barrel.

  26. Harold N. (verified owner)

    Let’s just say will definitely be buying from you guys again! The whole transaction was flawless from ship time to my front door as well as packaging. As for the 16 inch Rosco Bloodline barrel there is already enough YouTube videos on its performance and quality so no need to go over that for the millionth time. Very impressive! See you on the high ground! Hoo ah!!!!

  27. Davis (verified owner)

    Amazing barrel!! Great quality!

  28. Eric Post (verified owner)

    Amazing quality products and shipping. Extremely happy shopping with Rosco, will definitely be my go to.

  29. blakesmoker20 (verified owner)

    Great barrel, never disappointed with Rosco.

Add a review

Your email address will not be published. Required fields are marked *