Hey Guys,
I know the MK22s haven't been getting much love on this forum and most favor the 10/22 but I'd like to shed some light on how awesome these tacticool .22s can really be. First off there are very few options when it comes to a pre-built tacticool .22 that isn't restricted. Fortunately this guy is one of those non-restricted rifles. To me its a huge bonus as I can take it out plinking and am not restricted on mag capacity.
The MK22 has taken some heat in the past about the BCG bolt not being long enough and needing loctite. The one I got was of the second generation. From my understanding they have been fixed for quite some time and I can vouch for mine. The BCG bolt was definitely longer and had loctite on it. There was plenty of loctite on most other bolts too and overall it was and is still holding solid.
The other piece that was criticized was the stock. ISSC was quick to fix this and my stock is very sturdy. I met another fellow who had one of the first generation MK22s and his comment as well was that the stock is MUCH better than his.
Finally, there have been issues with light primer strikes. There are couple fixes for this and are well documented. The trigger group and BCG is exactly the same as the GSG5 as well, so there is plenty of information out there.
There were a few fixes I did to make sure everything runs smooth.
Firing pin:
-Stoned the firing pin (not sure if it was necessary but I did it anyways)
-Removed 2 coils on the FP return spring (This definitely made the FP hit harder. Have not had a light strike in the last 400 rounds I put through it
Trigger:
-Epoxy fix to remove trigger creep. This is pretty well documented for the GSG5. With a dremel and a couple washers you can easily remove the trigger creep. I did mine with epoxy as well. Definitely worthwhile if you're comfortable doing it
Body:
-Replaced 2 takedown screws with small HK push pins. These are available for the GSG5 and are relatively inexpensive. They make tearing down this rifle for cleaning a snap as all you have to do is pop out 2 pins and your lower is off.
Aesthetic modifications:
-Cut out the web inside the trigger guard. Looks more SCAR-ish now
-Replaced flash hider with thread adapter made by user willisworms here
-coming soon: Gen 3 SCAR cheek riser
Here are some quick pictures:
comparison of 1) Stock flash hider 2) thread adapter from willisworms with muzzlebrake 3) Thread adapter without the 1/2x28 thread to shorten the barrel (also willisworms handywork)
More views of the thread adapter:
The last time I took this guy out I had 1 stovepipe and 1 failure to fire in 400 rounds. I'm pretty sure both were due to crappy ammo as some of the bullets were loose in the casing and the fail to fire had a strong deep strike from the firing pin. The trigger is clean and crisp and this thing is a ton of fun. For those of you on the fence, I highly recommend this rifle. For those that have it and aren't impressed, try some of the mods and don't give up on it.
I know the MK22s haven't been getting much love on this forum and most favor the 10/22 but I'd like to shed some light on how awesome these tacticool .22s can really be. First off there are very few options when it comes to a pre-built tacticool .22 that isn't restricted. Fortunately this guy is one of those non-restricted rifles. To me its a huge bonus as I can take it out plinking and am not restricted on mag capacity.
The MK22 has taken some heat in the past about the BCG bolt not being long enough and needing loctite. The one I got was of the second generation. From my understanding they have been fixed for quite some time and I can vouch for mine. The BCG bolt was definitely longer and had loctite on it. There was plenty of loctite on most other bolts too and overall it was and is still holding solid.
The other piece that was criticized was the stock. ISSC was quick to fix this and my stock is very sturdy. I met another fellow who had one of the first generation MK22s and his comment as well was that the stock is MUCH better than his.
Finally, there have been issues with light primer strikes. There are couple fixes for this and are well documented. The trigger group and BCG is exactly the same as the GSG5 as well, so there is plenty of information out there.
There were a few fixes I did to make sure everything runs smooth.
Firing pin:
-Stoned the firing pin (not sure if it was necessary but I did it anyways)
-Removed 2 coils on the FP return spring (This definitely made the FP hit harder. Have not had a light strike in the last 400 rounds I put through it
Trigger:
-Epoxy fix to remove trigger creep. This is pretty well documented for the GSG5. With a dremel and a couple washers you can easily remove the trigger creep. I did mine with epoxy as well. Definitely worthwhile if you're comfortable doing it
Body:
-Replaced 2 takedown screws with small HK push pins. These are available for the GSG5 and are relatively inexpensive. They make tearing down this rifle for cleaning a snap as all you have to do is pop out 2 pins and your lower is off.
Aesthetic modifications:
-Cut out the web inside the trigger guard. Looks more SCAR-ish now
-Replaced flash hider with thread adapter made by user willisworms here
-coming soon: Gen 3 SCAR cheek riser
Here are some quick pictures:
comparison of 1) Stock flash hider 2) thread adapter from willisworms with muzzlebrake 3) Thread adapter without the 1/2x28 thread to shorten the barrel (also willisworms handywork)

More views of the thread adapter:


The last time I took this guy out I had 1 stovepipe and 1 failure to fire in 400 rounds. I'm pretty sure both were due to crappy ammo as some of the bullets were loose in the casing and the fail to fire had a strong deep strike from the firing pin. The trigger is clean and crisp and this thing is a ton of fun. For those of you on the fence, I highly recommend this rifle. For those that have it and aren't impressed, try some of the mods and don't give up on it.