Item for sale is a bullet feeding guide for the MCR, otherwise known as the Shrike/MCR feed insert.
The design and current dimension for this is based on my own measurements and trial & error, but the idea came from Mark G.'s design. After many iteration of the design, I finally came out with one I'm happy with. I have test fired and had no reliability issues. A board member generously lent his original insert to me. I used it to do some comparisons to mine version. I did not do live firing on his when comparing since I didn't want to risk damaging it, however I did test it on a version I duplicated from the original and it fired without issue.
Your choice is to purchase my design, or a clone of the original.
Price for one is $90 shipped via USPS.
Price for two is $170 shipped via USPS.
If you need a different carrier, let me know and I can let you know the price difference.
Payment method is Zelle, Venmo, or PayPal (you pay the fee or pay Friend & Family)
Earlier proof of life video: https://vimeo.com/735885372
My observations between his and mine dealing form/fit/function were:
My bullet guide is a bit more aggressive design to force the bullet nose up. I had done this on purpose to ensure the bullet tip would be guided more towards the center of the chamber.
The fit of the original was very loose. Every time opening the top cover it would fall out. My version I added a ball detent to keep it in place. Not a big deal since you could have shimmed the original in.
Note 1: My design (before I received the original insert) was actually form fitting to my top cover, but since original one was more narrower, I decided to match it. I wanted to ensure that mine would fit in all top covers. I had heard from some owners of the original insert that the fit was tight. I added the ball detent to ensure it keeps it from falling out. I tell you.. it was annoying to have to hold the insert in place when closing the top cover.
Note 2: I could have done the shim method.. but it really gets tight. If you wanted to remove it, it would have been a struggle if it was tight. I did experiment with adding built in shims to file down but I found it was really tight. Plus there was no guarantee that the shim I used material would not eventually compress under fire, hence it would falling out like the original in the future. The ball detent is a bit more work and cost more to do, but it offered a great benefit.
My guide section is a bit concaved in the shape to the shape of the bullet head. I doubt this makes mine better or worse than the original. The purpose was to give it enough space to not interfere with the feeding assembly.
The slide ramping of when the bullet pulled into place is a bit different angle at the shoulder.
The original is smoother due to how it was molded. I don't think mine will have any negative affect here, but definitely the original is smoother than mine.
The original is more brittle. Due to the material it appear it could chip. The loaner I borrowed has a very minor chip due to the material going to a thin peak. I made mine a bit thicker due to that observation.
Is the mine better than the original? Perhaps, but I can't tell with the small sample size of shooting.
Will this fix every issue with the MCR? No it will not fix every issue of the MCR. Some of the later generation MCRs are less sensitive to feeding due to the feed plate. However with the guide, it would force the bullet head to center more towards the the chamber.
How long will it last? I can't say since I have only a couple hundred rounds though my testing. After the test firing, it looked like it had little to no wear. Since the bullet was not designed to scrap and slide on the guide, I believe it should last a long time.
Since this a design based off of a specific MCR, there may be some sanding or fitting required. I tried to eliminate some of that with the ball detent, but I can't guarantee the milled depth being deeper or more shallow. If you have issues, I would want to know so I can make this product better.
If you have any questions, please feel free to ask.