New P Series Micro Block Piston System from Adams Arms

Adams Arms

Adams Arms announced the company is now selling its new P Series Micro Block piston systems for AR style rifles and pistols. These kits are designed to replace the typical direct impingement system common to the AR platform with a short stroke piston.

Adams Arms has been selling piston kits and rifles for a while now, so this is not its first offering. That means the company has a fair amount of experience with these kinds of systems. Here are a few of the features associated with the new kits.

The kits use a P Series Micro Block to siphon gasses from the barrel. The block is 40% lighter than the previous XLP block. The block direct gasses toward the drive rod which in turns operates the patented one piece bolt carrier.

According to the company, the parts have a LifeCoat finish that is corrosive resistant. All of the parts are backed by a lifetime warranty and are made in the United States.

The block can be purchased alone for $138.59. However, I suspect most people will buy the block as part of a full kit. Adams Arms offers kits in four different lengths: rifle, mid, carbine and pistol. All of the sizes are sold for the same price: $274.99.

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  • DoctorH


  • Evan

    Seems pretty cool. If I ever get around to building an AR, I’d consider using it.

  • Adam W

    I have an Adam’s arms rifle and absolutely love it. I’ve been waiting for them to release a .650 gas block forever now so I can retro fit my non-Adam’s arms rifles with their system. I hope this new release is available for more than just the classic .750 profile barrels.

    • Russ Kell

      They made a .625 gas block for their ULW offerings and kits. I have two (XLP series, 3-position type, not the newer multi-position model) .625 blocks. They do not make them any longer, however.

      • Adam W

        Really? That is awesome to know. I guess I need to contact their customer support and see if they have any old stock or plans to release small batches.

        • Russ Kell

          Maybe. I emailed them about a year ago to see if they had any or were making more and they said ‘nyet’.

          That said, there are a few of the kits still floating around out there. Do a search for “Adams Arms .625 Gas Block”, or “Adams Arms .625 Conversion”.

          A few places have just the .625 Piston Block for sale for around $60’ish (Newegg of all places is one). The .625 blocks will work with all of you other piston parts. it is basically the same as the low pro .750 block, with just a smaller barrel opening.

          I’m in the process of swapping one of my .625s for an XLP (more adjustments) on a Suppressor host (new barrel as well). Wish they’d made a .625 XLP, but nope.

  • Jack

    Why is this the same price as the XLP block? It’s half the size and way less complex. I’ve got an Adams upper with the “lite” gas block and I don’t need the adjustability but that price isn’t worth the weight savings.

  • Ark

    …But why?

    The big advantage of the AR platform is having the recoil impulse in line with the barrel. The action is opened by the piston in the BCG thrusting forward against the breach. With a piston system, the recoil impulse is off-center, pushing against the top of the BCG. AR receivers aren’t designed for off-center thrust on the BCG.

    Yeah, maybe it runs a little cleaner. So what? It’s not like there is an epidemic of AR failures due to the impingement system.

    And if you do want a piston-operated rifle, a retrofit kit isn’t the way to go. With a pistol design, you don’t need a buffer tube. You’ve already lost the inline recoil impulse, so you might as well go with a shorter bolt carrier and a different recoil spring location. Add a piston to a base AR and you’ve lost half the AR’s advantages and gained…well, nothing.

    • Anonymoose

      SIG Sauer hasn’t released their MCX buffer kits yet.

    • Christian Hedegaard-Schou

      But some people like adding extra non-standard moving parts to an otherwise standardized and reliable rifle!!

      • Machinegunnertim

        What fools they are! We better tell the navy seals ditch that unreliable 416.

    • int19h

      > Yeah, maybe it runs a little cleaner. So what? It’s not like there is an epidemic of AR failures due to the impingement system.

      Some people just want to clean less often, you know.

      • CommonSense23

        Then just clean less often. Its not going to effect the reliability of a AR15.

    • Machinegunnertim

      The recoil impulse is not pushed off center, that’s silly. The BCG and buffer still move in the same path and generate the majority of the recoil just like direct gas. I fired many M16’s on active duty and i have owned several Adams Arms uppers for years and there is no noticeable difference in recoil. There is also no extra wear.

      Direct gas is perfectly reliable but so have been my AA pistons, I just like them better so it comes down to personal preference. And it works better with my suppressors.

  • Joe

    I didn’t read “adjustable gas block”, hm. Would this be less gassy suppressed? Looking for a reason, just not seeing one.


    sounds good to me !

  • RogUinta

    This would be a big plus for suppressing my .300 BLK SBR, I think. I’ve been looking everywhere for a decent pistol-length piston kit.

    And before anyone asks, I’m a lefty so I get the full blast of gas/junk from the ejection port straight to the face when suppressing any AR-pattern gun.

    • Darren

      Stag Arms makes a left handed upper thats worth a look.

  • dave

    Im an advocate for superlative arms piston kit.
    Bonus: when ordering from their site le/mil get 20% disc when it ships

  • MissileMech

    It looks like Superlative Arms has impacted AA’s bottom line.

  • Sledgecrowbar

    40% of the weight of a gas block isn’t the weight savings I really yearn for. Also, it appears to be at the expense of adjustment. Good for them for coming out with the option, though.

    I bought an Osprey kit a few years back and have been entirely unable to get it to fit under any handguards I buy for it. They have a (hopelessly small) list of compatible models but none that I like. So I was looking at getting a Superlative Arms setup since Bill Alexander’s business policies never endeared me to his products. After over a month of no response on a question sent through multiple methods to Superlative, which seems to be addressed to a fly-by-night style rental garage location, I’m pretty sure I will actually be going with an Adams Arms piston setup, because of all the available piston kits out right now (the three I’ve mentioned), this line has been out the longest.

  • Russ Kell

    YW, Adam. Glad I could help. Enjoy!