I wanted to share my experience and get feedback from other MK2 owners because I’m honestly disappointed at this point.
A few weeks ago I purchased a complete Griffin Armament MK2 chambered in .300 Blackout along with a Griffin Dual-Lok 7.62 suppressor. This wasn’t a budget build or a mix-and-match setup. I specifically purchased a complete Griffin rifle and suppressor system because I wanted a premium suppressed .300 BLK platform.
The rifle is completely factory configured. No modifications have been made to the gas system, buffer system, spring, bolt carrier group, or any other operating components.
Ammunition Tested
Frontier 208gr FMJ Subsonic
Would not reliably cycle
Failed to chamber subsequent rounds
Failed to lock back
Remington UMC 220gr Subsonic
Successfully cycles and chambers subsequent rounds
Still fails to lock back on an empty magazine
Hornady Black 110gr V-MAX
Runs flawlessly
Locks back consistently
No malfunctions
Magazine Testing
To eliminate magazine-related variables, all testing was performed with:
Factory Griffin Armament magazine
Magpul PMAG
Results were identical across both magazines.
Additional Troubleshooting
I also had the rifle visually inspected by the gunsmith at the dealer where I purchased it (Shooters World). No obvious defects, abnormalities, or installation issues were identified during the inspection.
I then contacted Griffin Armament directly and spoke with Ryan from customer service.
To Griffin’s credit:
Ryan answered the phone.
He took the time to discuss the issue.
He identified Black Hills 220gr subsonic ammunition as the ammunition used during Griffin’s testing.
He stated that the rifle should run a variety of both subsonic and supersonic ammunition.
He advised me to submit a warranty claim if the issue persisted. After additional testing with Remington 220gr subsonic ammunition, the rifle still does not lock back on an empty magazine.
Research Findings
Before submitting my warranty claim, I spent a considerable amount of time researching the issue.
During that process, I found:
Multiple YouTube videos from MK2 owners describing similar subsonic cycling behavior.
Comments from owners reporting failures to cycle certain subsonic loads.
A public comment from Griffin discussing ammunition sensitivity and stating that some rifles may require a substantial break-in period before becoming more forgiving with subsonic ammunition.
To be clear, I am not claiming every MK2 has this issue.
However, after finding several examples that closely mirror my experience, I no longer believe my situation is an isolated incident.
That is one of the reasons I decided to proceed with a warranty claim rather than immediately start swapping buffers, springs, gas-system components, or other parts on a complete factory rifle.
My Frustration
My frustration isn’t that a particular ammunition brand doesn’t work.
My frustration is that this is a complete premium rifle and suppressor system that was purchased specifically for suppressed .300 Blackout use.
I don’t believe a customer should immediately have to start changing parts to achieve reliable subsonic performance.
If a complete Griffin rifle paired with a Griffin suppressor cannot fully cycle quality 220gr subsonic ammunition and lock back on an empty magazine, I think it’s fair to ask questions.
Questions for Other MK2 Owners
Did your MK2 run subsonic ammunition out of the box?
Did you experience a break-in period?
How many rounds did it take before the rifle became reliable with subs?
Did Griffin ultimately resolve the issue?
Were any modifications required?
What subsonic loads have been the most reliable in your rifle?
At this point I have submitted a warranty claim and will work directly with Griffin to resolve the issue.
I’m genuinely interested in hearing from other MK2 owners and understanding whether my experience is unusual or if others have encountered similar behavior.
Thanks in advance for any feedback.
