I decided to show you guys what I did to fix my Mk22 issues. To start off I'd like to say that anything you see shall be attempted at your own risk and I do not take any responsibility if you break something or hurt yourself or others. These fixes addressed my issues and may or may not work for you.
Ok so first time out with the rifle I had the same issues everyone else is having. Light primer strikes, failure to extract causing stove pipes, etc. I got fed up and decided to tear it apart to see what makes her tick. Being a self proclaimed mechanical engineer I was sure I could come up with a very simple solution. One of the very first things I noticed was that there was a significant gap between the bolt carrier assembly and the breech block.
I measured about 1/32" of play which is about the size of the casing rim. I decided to make a very simple mod involving a washer and super glue. I sanded the retainer at the rear along with the washer to create a rough surface and applied some super glue then put the washer on and assembled the gun squeezing the surfaces together. (Washer still holds fine and have never had it come off while disassembling the rifle)
The washer pushes the bolt carrier assembly forward to close up the gap. Without the gap the casing sits tightly between the bolt and the breech block.
I also notched the back side of the carrier retainer where it sits flat against the receiver to make future removal easier. Now all you have to do is wedge a small flat head in there.
Back to the range after this mod and WOW! what a difference. But I still had the occasional light primer strike. So I decided to dig more. One of the other things I noticed is that the firing pin seems to stop short as shown below. I filed a bit down so the top is fllush with the bolt once fully forward. This still gave me some clearance for the casing rim.
Before
After
I also noticed that the bolt return springs were a bit weak causing the bolt to sometimes stall and not fully load the next round in to the breech. I made two spacers and installed them in front of the springs.
Back to the range! 5 mags without a single hiccup, I think I fixed the issues for good but will continue testing. Here is my setup and I'm getting some decent groupings too considering the 3MOA dot on that bushnell scope covers up the small bullseye. So far I am happy with the setup and performance.
Groupings @ 50yds using cheap winchester 36 grain copper plated hollow points.
Another mod I did was to drill this hole to a 1/32" This allows me to use my smallest allen key to push out the pin that retains the firing pin. This way I can limit the tools I carry as everything I need to service the rifle in the field is on board with me.
The tools I carry inside the grip including the bore snake. These tools allow me to field strip what I need to including the magazine for maintenance. I still have room for a small cloth a bag of grease and a spare battery for the optic. I do have a Otis cleaning kit but the idea here is to have everything in a small package in a survival situation.
I also removed the poorly designed firing pin safety and the magazine safety. My Ruger 10/22 and Marlin model 60 dont have these devices and neither should my Mk22.
The grease I use to keep her lubed up. I have always followed the general industry rule of "grease for sliding parts and oil for rotating parts". Grease also likes to stay where its put and doesn't wash out. So far I have not had issues with the carbon and grease mixing and jamming things up. I am in the process of testing this by only wiping the bore with the bore snake once after every day of shooting for a consecutive 7 days of shooting.
I spent another couple hours at the range doing more testing. Shot 25 mags thats 600 rounds without a single hiccup again. I am confident to say that this series of mods worked like a charm.
So here are a few videos of my wife and I firing the rifle with 100% confidence that it wont jam. 25 magazine fulls = 600rds + Not a single issue = Fun! Ammo used was Winchester 36 Grain copper plated hollow point. The kind that you get in a 555rd value box. This ammo is actually quite impressive. It was very consistent with only a couple fliers here and there.
http://www.youtube.com/watch?v=_A9D4tDtMAk
http://www.youtube.com/watch?v=yrGnWVyC1tU
http://www.youtube.com/watch?v=35VR_McufPQ
Fix your ISSC Mk22 for good!
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