8" 300BLK Complete Low Profile Piston Upper with A.P. 7" M-Lok Handguard

Question

Q: I’m curious as to whether I’d be able to swap barrels if I got one, I.e. let’s say I bought a 8”.300 piston upper and I want to swap the barrel for a longer one or maybe a different caliber, or if I bought a 556 uppper, would the same rules apply?

Asked by: Josh - 1/18/2026

Q: Does it require a buffer or will it run without one

Asked by: Barrett - 8/17/2024

Q: Looks like you use the aero enhanced handgaurd. Do you also use their stripped upper for this completed upper? (Curious about fit with their lower)

Asked by: Bobthebuilder - 1/9/2023

Q: Is there a way to order just the handguard and barrel nut for the piston system on your 8 inch complete upper?

Asked by: Brandon Mitchell - 9/22/2022

Q: Does this come with the required buffer adapter for a mil-spec AR15 lower?

Asked by: Eric - 9/8/2022

Q: is the piston system adjustable?

Asked by: Josh - 5/24/2022

Q: Is it a full auto bolt? Is upper cut to fit a registered drop in auto sear?

Asked by: Rick - 12/25/2021

Q: Do the 300 blk uppers come with a bolt carrier.

Asked by: Jake - 1/6/2021

Q: when will these back in stock? Thank you.

Asked by: RLBone - 6/9/2020

Q: Will this cycle sub loads with or without suppressor attached?

Asked by: RL Bone - 5/10/2020

Questions about this item? Ask here.

Accepted Answer

All piston systems are precision tuned for gas operating length, barrel length for each caliber, so if you swapped barrels it will affect performance.

Accepted Answer

A: All of our piston uppers require a mil-spec AR-15 lower with buffer, springs, etc.

Answer provided by: Administrator (8/19/2024)

Accepted Answer

We use our own uppers that are spec'd to our drawings as we use a rocker bushing in our 300BLK in order to rock the op rod out on pistol gas operating length uppers. You can see our 300BLK piston upper video in how the rocker bushing works here: https://www.blackriflearms.com/PISTON-VIDEOS_ep_40.html

We have not heard of any fitment issues with Aero lowers.

Accepted Answer

No, not at this time as we designed our proprietary barrel nut for use with Aero Enhanced Handguard with our piston uppers.

Accepted Answer

No, this product is a complete upper with no lower parts included. This complete upper is ready to pin onto a complete lower. Buffer or any lower parts are considered lower parts and not part of this complete upper.

Accepted Answer

Our 300 Blackout system is nonadjustable. It was determined during our R&D process that by utilizing a piston of a particular size and proper positioning of the gas port location we could achieve outstanding reliability without adding the complexity of a regulated system. Although we are known for our regulated piston systems and really believe in them only because they offer significant benefits with typical rifle calibers especially with suppressed firearm due to suppressor backpressure that may increase bolt carrier velocity by as much as 30 percent. Our regulators provide a means to mitigate over gas situation and compensate for underpowered ammunition as well. All of which is common with standard rifle calibers. However, 300BLK self-mitigates these gassing issues to a significate degree by virtue of its design. For example, with subsonic ammunition you have a bullet that is typically twice the weight of a supersonic bullet, and it is moving at less than haft the velocity. This creates a situation where subsonic bullets are in the barrel about twice as long providing a longer gas impulse. Conversely supersonic bullets are moving about twice as fast and at much higher pressure. These characteristics enable us to utilize our piston system and gas port positioning to effectively balance between the longer dwell time of subs versus higher peek pressure of supersonic ammunition. The key here is we balancing gas pressure and dwell time with piston size and gas port positioning to optimize reliability, thus eliminating the need to regulate our 300BLK system.

Accepted Answer

Yes our bolt carriers are full auto. Our uppers are mil-spec so any drop in auto sear designed to be used in mil-spec uppers will work. We run our systems full auto all the time.

Accepted Answer

Yes it comes with a bolt carrier. It's a complete upper receiver ready to be pinned onto a lower.

Accepted Answer

A: We estimate in about 3 to 4 weeks, but it could be a little longer.

Answer provided by: Customer Service (6/9/2020)

Accepted Answer

Due to the length of the 8" barrel, it may not lock the bolt back on the last round. The 8" 300BLK will shoot subsonic optimally with a silencer and supersonic with or without a silencer. If you want to shoot subs with or without a silencer please look at the 10" 300BLK piston uppers.

8" 300BLK Complete Low Profile Piston Upper with A.P. 7" M-Lok Handguard

Choose Options

Related Items

Recently Viewed Items

8" 300BLK Complete Low Profile Piston Upper with A.P. 7" M-Lok Handguard

Choose Options

Related Items

Recently Viewed Items

Mailing List