First the barrel, then the bolt

Solider Systems published this PEO Solider PowerPoint slide showing the phases of the M4A1 Carbine upgrade. First the barrel, trigger and fire controls will be upgraded, followed by the rail system, bolt and bolt carrier.

[ Many thanks to Lance for emailing me the link. ]

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Wolfwood

    And this is truly cheaper, in parts, labor, and shipping, than simply replacing the whole thing and selling the de-auto’ed old ones through the CMP?

  • Lance

    I don’t get why the piston upgrade is last. maybe they’ll have a BIG competition for the best conversion kit. Im excited about a New AR bolt that will be stronger. One BIG weakness of the Stoner system was the Bolt had a weak point and while this stood up in 20inch rifles fine when in a shortened gas system of a carbine will break the bolt in half. A new bolt and piston system will fix this. Iam very excited to see what the full new and improved carbine will look like when they are finished with all steps of the competition in 2012/3.

  • I can confirm that a contract modification has been made with Colt to substitute M4A1 equipped with the SOCOM heavy barrel and ambidextrous selector for a number of back-ordered M4.

  • root man

    At least they are improving it.
    The osprey piston may finish the thing off and we will have a decent rifle after 40 years..
    Next thing is to get the 6.5 in it and move on to getting rid of the m9..

  • jdun1911

    What is the weight of SOCOM heavy barrel. Around Hbar? If it anywhere near Hbar it will be a nightmare. I’ve handle Hbar carbine and boy they are very unbalance/front heavy.

    I sure hope they understand what they are getting into. Other than being heavy, heavy barrel will take longer to heat up but it also take longer to cool down. In certain situation it might cause troubles.


    This is what happen when the military demilled/de-auto’ed M16.

    Anyway there are still A1 receiver being use in the National Guards and ROTC (IIRC).

  • Lance

    USCG, and Navy reserve and Air Force Police still have units with M-16A1s. One of the reasons the Lake City armory is stil makeing M-193 ammo. Most ful time units in all services have either a M-4 or a M-16A2 (Except marines who have M-16A4s). I hope they’ll sell more A1 parts kits with a Nodak Spud reciver you have a awsome Vietnam style AR-15A1 rifle.


    The M-4A1 barrel is not a Hbar barrel and still has some light sections to fit a standerd M-203 GL. It is a bit heaver under the handguards and yes a bit heaver but more relighable. Even if we still used a light barrel the piston system will add weight to the front or the carbine. I think a SOPMOD buttstock will balence it out.

  • I have to agree with Wolfwood, sounds like by the time you add in time spent fitting new parts, cost of parts, etc., that it would be more logical just to buy a new weapon.

  • Bram

    Nice PowerPoint from some Pentagon Colonel who has probably never carried a rifle in a combat zone. He has some good catch phrases, a new acronym, a really slow website that only shows the PowerPoint page again, and some humor (Full and Open Competition made me laugh).

    Well done Chairborne Ranger! A few more like this and you’ll be seeing stars.

    Meanwhile our soldiers will continue to be issued a crappy rifle designed 60 years ago – reworked with crap glued on like a hopped up old Trans Am.

  • jdun1911

    root man,

    The osprey piston has it own set of problems as documented by people that have used it more than a few times a year.

    Andrew did two reviews on Osprey marketing a year back.


    I hope they know what they are doing. By eyeballing it, the weight of the carbine will be over 12lbs with everything on it (light, laser, rail, piston, grip pod, heavy barrel, etc). 95% of the weight will be at the front. Not the ideal setup IMO.

    Like I said before if I’m going to hump a heavy ass carbine might as well hump a bigger caliber. Plain FAL carbine is around 8lbs IIRC.

    That’s reminds me. A few years back my cousin built a Hbar upper. I told him it was a waste of time and money. Way too unbalance for what you get out of it. But no no one every take my advices. What happen? A few weeks later he took it apart and sold the barrel.

    For anything that is not related to “get the most accuracy out of your barrel”, I’ll stay away from heavy barrel like it was the black plague.

  • Lance

    @ Wolfwood bram and Zermoid

    The upgrade is far more logical than buying the K&K 416 and yes it would be a 416 or some sort of piston AR would win. The fact is the upgrade will be less in cost since all the new guns like H&K Ruger SIG Colt LWIC will cost $2000 plus dollars a peice and be way more expensive. Spending $900 for a M-4A1 and a piston conversion kit is $1100 dollars cheaper and is better than haveing our guns made in europe.


    I thought you agreed with me on the upgrade? Dont worry about the barrel change ive handled hevier carbine barrels, and they arnt a bad Hbar weight SOCOM had ad high remarks on the M-4A1 barrel and its designed to be ballenced more than commercial HBAR barrels. I dont know if they will replace DI with a piston. That pahse is last and id relighabliltiy problems improve it can be stoped there. Osprey might not be the winner of the competition anyway Olympic Arms have made a exillent light weight piston conversin and ive handled them my slef they make a good ballence.

    Just dont worry they arnt HBARs there a bit heavier carbine barrel.

  • root man

    Yeah jdun1911 there are problems with everything.
    What exactly is your solution to the worlds problems..
    The acr? 😉
    About the only thing I am with you on is 1911 (unless that has too many problems..?)

  • subase

    See what happens when you complain? You get a heavier, no more accurate or reliable rifle.

    I would have been more than satisfied with just a nickel boron coated bolt (less problematic than a piston system) and a electronic round counter.

    That would have gotten rid of the problem of it’s finicky maintenance and the guesstimates on parts wearing out.

  • Wolfwood and Zermoid:
    Individual parts like bolts and barrels wear out, spares are commonly purchased, and depot repair and furbishment of weapons are routine. Swapping in improved versions of these parts could be handled in the same fashion.

    jdun1911: The added weight of accessories are going to remain constant no matter what carbine or rifle is used. Nobody is going to go back to iron sights and no accessories.

  • Travis


    Wouldn’t the cost of retraining all 1,000,000+ personnel in our armed forces on a new carbine figure into the equation somehow? It seems only logical that it would and we’ve already seen what happens when you hand out a new rifle to troops who aren’t trained to maintain it.