M*CARBO Brotherhood

Ruger PC carbine bolt pins

Hi everyone, new to this forum.
I just got myself a new ruger pc carbine chassis model.
I haven’t taken it to the range yet and decided to install m*carbo upgrades.

For the upgraded bolt pins, either of the pins would not insert fully on one of the bolt holes of the bolt assembly just with the bolt face installed (without firing pin spring).
But when I test fit without the bolt face, both of the upgrade pins would insert fine on that particular hole.
I just didn’t want to force it as I may have issues taking it off for disassembly.

So what I did for now is put back the factory ruger bolt pins hoping that when I try this again after few hundred rounds, I wouldn’t have this issue.

Anyone had experienced this or any advice?

Hello and welcome to M*CARBO family.

I would start with a micrometer reading on all of the pins and holes.

Some good pictures of everything helps us to help you.

I’m using the M*CARBO pins with no issues.

Breaking in the firearm before modding is the best way to start…then add mods one at a time.

Keep us updated. Enjoy the PCC9.


Thanks MountainHunter.
I’ll pop few hundred rounds on it and re-attempt this bolt pins upgrade.
I could not attribute the issue to m*carbo bolt pins as both inserted fine on the bolt holes (without bolt face). I suspect would be a minimal tolerance/ or bur on the bolt face notch which contacts the pin.


M*CARBO technicians are always happy to discuss any possible issues and solutions. You might want to contact them as well.

Good luck and let us know how it proceeds.

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I just shoot them an email.
I measured the mcarbo pins are 0.156" ~ 3.96mm
Will update here when I hear from them.


Being up north, I received replacement mcarbo bolt head pins from one of their distributors.
Since taking down of this rifle is a bit cumbersome and requires tools, so I was just able to try it during cleaning. Unfortunately that particular hole for left bolt pin still wouldn’t accept either of the bolt pins.
So, I took time last Friday during another cleaning session, and discovered a bur on the recess of the bolt. So I just deburred it with few swipes of flat screw driver and the pin smoothly dropped in place!
I put a yellow line (sorry it’s not noticeable enough) on the right recess of the bolt, the area I had issues with.

I just hope these pins I got won’t break on me as I read few weeks ago that even these mcarbo pins do break as well as factory ones.

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@ybrik Glad you found the issue and fixed it. Let Ruger know of the issue. They might send you a new bolt face under warranty. Having a spare would be excellent.

Good advice! But I doubt they would send a new one for having an issue with aftermarket bolt pins. Besides that, I’m located in Canada and I read that Ruger requires sending them the whole firearm should there be an issue even with only a small part that they can just send/mail directly to the owner.