M*CARBO Brotherhood

Light and no primer strikes

Greetings all. New member here with a brand new PC Carbine that, before even shooting, I bought and installed the M*Carbo Ruger PC Carbine All In One Pro Performance Bundle. Now, either I installed something incorrectly, or there was an issue with the firearm. I have tried three different types of 9MM ammo, different Glock Factory Mags and different shooters with the same results. Some of the discarded ammo was obviously fouled with carbon, but no strike.
Any thoughts other than "put it back to factory and retest?
Obviously, I will be doing that next, but I’d like to be able to re-install the performance kit and would like to know what to watch out for while doing it.

Thanks all!!!


Hi, James, and welcome to the brotherhood.

I’m going to ask a lot of questions and maybe one of them will turn on a light bulb. Light strikes or no strikes at all? Can you see a dimple from the firing pin on the primer of a case that didn’t fire?

Obviously, there are two places to look - the bolt and the trigger group. Is the bolt put together correctly? No binding or rubbing, firing pin channel clean and no oil in it, firing pin moves easily and spring pushes it back? Does the firing pin look okay, not bent, the tip isn’t damaged? Does it protrude through the bolt head when you push it forward? Is the bolt in battery?

Is the trigger group put back together correctly? No binding, nothing rubbing, hammer strut seated correctly on both ends, spring and clip in place? Sear, sear spring, and disconnect correct? Does the hammer release correctly with decent force when the trigger group isn’t in the rifle?

After rechecking your assembly, you can test whether you’re getting a good primer strike before making a trip to the range by putting a drop of candle wax on the “primer” of a snap cap. Pull the trigger and if you see a decent impression from the firing pin, it’s probably good to go…

The nice thing about the PCC is how easy it is to tear it down and put back together. Chris Nelson’s how-to videos are really good (except you don’t remove the takedown screws since they’re captured LOL).

Maybe other members can think of something I didn’t cover.


Hey Phuzzy42!

Ok… If the firearm fires, then the divit in the primer looks fine. On the non-fired rounds, nothing at all. Not even a scratch.

The firing pin looks to be functional and it does impact the primer of some, just not all… The bolt seems to be opening and closing fully and will lock open when empty or locked back manually.

I took the trigger assembly apart again and swapped out the hammer spring with the original and while it made a difference, the issue persisted.

So far, that’s all I have. But still working on it.



Ok, either the hammer isn’t hitting the firing pin hard enough or something is obstructing the firing pin. Pull the trigger group out and put your finger over the hammer so it doesn’t snap forward too far. When you pull the trigger does it jump forward with a fair amount of force? Do it several times. Same every time?

Take the bolt out. Does the firing pin protrude from the back so the hammer can hit it? When you push the firing pin forward does it protrude from the bolt face far enough to hit the primer? When you release it does it spring back? Any hangups? Does it feel gritty? You don’t want any lubricants in the firing pin channel because oils don’t compress and the firing pin could be slowed or blocked by hydraulic effects. Seems counter-intuitive not to oil something that moves, but…

If everything appears correct and you still have problems, put everything back to stock and see if the problems go away. If it’s still not working 100%, it’s time to call Ruger.


I’d say @phuzzy42 covered it pretty well but if you get to the point quoted above and it does solve your problems, I’d suggest maybe reinstalling the MCARBO mod parts in stages, reassemble and test after adding each stage to see if everything is still working correctly. That way you can maybe root out the offending mod or combo of mods.

Oh, and welcome to the Brotherhood. :slightly_smiling_face:


@Buyer0601 Welcome to the Brotherhood.

Besides the hydraulic effects of oil in the firing pin channel, with the amount of blowback these designs have, some of that gunk mixing with oil in the firing pin channel is going to make a mess possibly slowing it down.


This is where the PCC really shines compared to the Sub2k - it’s very easy to take everything apart and put it back together. As dirty as blowback is, you gotta know the hammer and sear in the s2k is filthy after a couple hundred rounds with no way to clean and lube them except take the whole thing apart again. I haven’t done that 500 rounds after putting in the MCarbo parts but they’re going to need it sometime. That castle nut…


You ain’t kiddin’, brother. With these forums as evidence, I think it would be safe to say no one really wants to tear open their Subby unless they absolutely have to. I have to give it to Ruger on the refined design of the PCC given it’s a first generation firearm, though it likely benefited heavily from everything they learned on the 10/22 takedown models.


It is kind of a scaled-up 10/22 but thank God we aren’t stuck with that PITA rotary magazine. Ruger had an earlier version of a PC carbine but it didn’t take off and they stopped making it.


Well, moved almost everything back to stock, other than some pins, charging handle and the muzzle break. All issues have seemed to have resolved.

Pulled the firing pin and no issues there. Tested it on my finger (not the wisest idea, kinda hurt… DUH) anyway, time to start adding parts back.

The one issue I noticed was the trigger replacement did not hold the parts as well as the factory version. The trigger reset is much better on the factory. Not sure that means a thing, but just noticed it.

Any suggestions as to what order the parts should be added in? Otherwise, I’ll go at it randomly.

Thanks all!!


If I were doing this I’d probably reinstall all the trigger group mods except the hammer spring, then test again. A weaker hammer spring as the culprit makes sense if the rest of the system isn’t binding up somewhere, and you proved that when you used your finger as a snap cap (the usual method is to put the eraser end of a pencil on it and see how far it jumps when you pull the trigger). :grin:

If one pin works better than the other, then obviously use it. The trigger, its spring, and the sear spring will improve the trigger pull without affecting the hammer force, so use those too. The recoil spring, buffer, pins, and extractor don’t affect hammer force, so those should be good. With the amount of work you’ve put in on this already, I’d bet you can almost swap parts in the dark from memory, and do it all in 10 or 15 minutes.

Face it, though - even with the frustration, you’re having fun, and this is training for when you work on your next gun. And the next, and the next… LOL You might want to call MCARBO and see if they have suggestions for what will make everything work on the PCC the way it should. It may be nothing more than being broken in - everything’s tight when it hasn’t been used much (and no comments from the peanut gallery!) LOL


Thanks again for all the suggestions. I replaced all of the springs in the trigger assembly, but the hammer spring with everything else being stock. Same issue. I concluded the same as you suggested about the strength of the hammer spring, but alas was disappointed when the failure started almost immediately. Does that mean that the issue is the hammer spring or possibly somewhere else in the trigger group?

I fully enjoying the work and with my plans on getting the Sub-2K, better to practice on the simpler platform first!!!

Thanks All!!!


There are only two possibilities - either the hammer isn’t hitting the firing pin correctly or the firing pin isn’t moving like it’s supposed to.

With trigger group out of the gun:
Are all the parts installed correctly?
Anything too sloppy or too tight?
Springs properly installed in their recesses, especially the hammer strut?
Does the hammer snap forward correctly when you pull the trigger? Every time?
Is the hammer square with the trigger group? In other words, it’s not canting off to one side or the other so it doesn’t hit the firing pin squarely.

With the bolt out of the gun:
Are all the parts installed correctly?
Anything too sloppy or too tight?
Springs properly installed?
Firing pin channel clean and dry (no lube)? Moves ok? Protrudes from bolt face when pushed forward? Protrudes from bolt rear when NOT pushed forward?
Bolt face oriented correctly?
Extractor installed correctly? It moves against spring pressure?

If putting the whole thing back to stock makes the problems disappear, I’d leave it that way until you can consult MCARBO. They’re the experts, I’m just a novice.

Can anyone else in the brotherhood think of something I haven’t?


Maybe, but you helped get him back to a working firearm again. That counts for something, novice or not.

You covered everything I would have suggested, and probably in better detail. I got nuffin…well, actually…shot in the dark…

When you say you put it back to stock “other than some pins”, which MCARBO pins in particular did you leave in?


I left the Steel Trigger Group Pins, the Bolt head and Extractor pin Kits in the rifle.
Everything seems to be installed correctly (I have watched a number of videos about the trigger assembly and all matches). No slop in any of the parts. I pulled the bolt out and checked the firing pin assembly and extractor and everything looks correct.

Phuzzy, I’d like to thank you for all of your suggestions!! You have covered way more than I could have thought of.

Thanks all!!


I thought you might say that. Might be a long shot but if you’re feeling really froggy, maybe take a chance and put the original pins back in for the trigger group. At first look, those pins would be the last thing on anyone’s list as the source of the problem but…


I do not know what your qualifications are, however as a retired police armorer, one would think you would have put the gun back to factory before any negative postings. If you are a firearms expert I apologize, but then again that would mean you should be able to locate the issue and correct it. In my career I have found more kitchen table gunsmiths that have done significant damage with only good intentions. Put the gun back to factory specs, test fire it. If all is good, upgrade the gun ONE PART AT A TIME and test fire after each option is installed. It is unclear why the gun was not checked and test fired before ANY modifications. My recommendation is to bring it to a competent gunsmith or put it back to factory and send it back to the factory.


Two thumbs up :slightly_smiling_face:.


My apologies. I did not realize this forum was dedicated to expert level Armorers only.

To everyone else that responded in a helpful manner, I truly appreciate your assistance and guidance! If I at any time disparaged the M*Carbo product name, I would like to apologize, that was Never my intention. I thought it was obvious that my novice, “kitchen table gunsmith” skills were to blame and not the product.

Thank goodness I was set straight by a professional!


On my G2 S2K, I just lock the bolt back and hose the guts out through the ejection port with canned aerosol Breakfree until it runs out the bottom of the mag well as clean/clear as it’s going to get and wipe up what I can. The difference in clarity from start to finish is huge, so I know it’s doing something. Gets cleaned and lubed that way and it’s been working for me so far.

I didn’t read the whole thread in detail, so forgive me if I missed the following. As far as function, did you shoot it out of the box completely stock? If it was reliable, then something(s) went wrong with your aftermarket parts install. I always run a new gun in 100% bone stock because I won’t waste the time/expense of modding an unreliable gun. Plus, it makes it that much easier to send back to the manufacturer to fix it instead of having to remove any mods. I know Kel-Tec is cool with MCARBO parts installed, but is Ruger? It’s a generally good idea overall. Never know if a company will decide to just replace a broken firearm and, if so, would they remove and keep all your MCARBO parts to send back? Or, install them in the replacement firearm? Not something I’d trust them to do and/or without a charge.