carbon ring in chamber

[Battis]

Maybe this should have been in Gunsmithing...
My HK P7 has a ring of carbon in the chamber that's making the slide stick when ejecting a round by hand (it fires and ejects fine when shooting).
How would you remove that ring?

[G W Wade]

On my 38 special, I have belled a 357 case to just fit and pushed it in to remove carbon build up. If you could find a case similar enough to do it with the 9, ? Other than that Boer Tech makes C4 carbon blaster and others have similar. Plug barrel and fill it up Wait and should brush out Good luck, GW

[Battis]

I'll check out the C4 carbon blaster. Looks like they have it on Amazon.
Thanks.

[G W Wade]

Just had another wild idea. If you cut a 223 brass off at the shoulder it should be close to the right size to make a scraper GW

[DougGuy]

I would find a case that you could cut off so it is a snug fit in the chamber like GW said, but file a few notches in the end with a small flat file or a small round file so it has some teeth and see if it works.

It looks like you have almost straight on access to the rear of the barrel when the gun is field stripped.

[Thumbcocker]

Go to O'Reilly's and get can of Berryman's. Soak a cotton ball in it and push it into the chamber. Leave it overnight. Brush in the morning. Repeat if needed.

[Battis]

Great gun but apparently they're ammo fussy. There's a hole from the chamber down to the gas cylinder below that you have to be aware of. The gas piston in the gas cylinder gets fouled easily. I've been using Sellior & Bellot ammo but I think I'll reload with a cleaner powder.

[BK7saum]

What exactly are you considering a carbon ring? Location?

You obviously have a fluted chamber, but what I am seeing rearward if the flutes has me curious if it is a carbon ring or a stepped chamber. I am not familiar enough with the P7 to say one way or the other.

Standard chambers, the carbon ring is at the case mouth, between the case and the leade at the front of the chamber.

[shooting on a shoestring]

Yep. It’s an H&K stepped and fluted chamber.
I’m not seeing any carbon ring, which as BK7saum points out, occurs at the front of the chamber as the boolit exits the case mouth.

I do see 2 machined rings at the front of the chamber. One of them is the headspace stop. The other one is hmmmmm? It’s shiny so I don’t think that is a carbon ring. But maybe?

[elmacgyver0]

I have never been a big fan of fluted chambers, although the HK sub guns and rifles are some of the sexiest guns on the planet in my opinion.
I am not a fan of delayed blowback, but it seems to work well in most cases, evidently not so much here though.
A product called Breakthrough is available to clean suppressors that works very well to melt the carbon off of suppressor baffles.
I cannot see why it would not work as well on gun barrels.

[Battis]

Just before (rearward of) the flutes, there's a dark ring. It encircles the case mouth. It looks like a carbon ring but now I'm wondering.
The gun works perfectly when fired - it's only when trying to eject a round by working the slide that it sticks, almost as if the bullet isn't seated deep enough, or it's too fat. I'm using FMJ factory ammo (the ammo is dirty).
"Not a fan of fluted chambers or delayed blowback". Well, stay away from a P7, which is still the best gun I've ever owned.

[elmacgyver0]

I never said they were bad, just never been a fan of.
I do own a Cetme that I built from a parts kit, but the fluting never gave me good vibes.
The P7 from your description sounds very interesting, a hybrid of delayed blowback and gas operated.
If it is indeed gas operated, why the fluting?
Actually, in all fairness, I have never experienced the fluting to hinder reusing the cases for reloading, just cosmetics.

[Battis]

I'm at the beginning of the learning curve for this handgun. It shoots fine - the rounds all chamber, fire and eject. It's just this problem of not ejecting a round by hand. SnapCaps eject by hand, but not loaded rounds. It has to be a dirty chamber, or something that has to do with fouling. Apparently, an empty case will eject even if the extractor is broken. I read that the flutes float the case much like an air hockey table floats the puck.
It's very accurate, even makes me look good. The gas piston tames the snappy 9mm and the squeeze cocking makes less work for the trigger.
I like it.

[DougGuy]

Just before (rearward of) the flutes, there's a dark ring. It encircles the case mouth. It looks like a carbon ring but now I'm wondering.
The gun works perfectly when fired - it's only when trying to eject a round by working the slide that it sticks, almost as if the bullet isn't seated deep enough, or it's too fat. I'm using FMJ factory ammo (the ammo is dirty).
"Not a fan of fluted chambers or delayed blowback". Well, stay away from a P7, which is still the best gun I've ever owned.

Do the rounds plunk and spin with just the barrel sitting there, easy to get to? If they don't there is one of your issues, likely the throat is a tad bit too tight for the boolit/bullet style and you have a bit of interference with the flutes which the slide has enough velocity to seat the round despite a bit of resistance.

[Driver man]

Im of the opinion that it is a carbon ring etc as under magnification the outline is very irregular. I would flare a case after sharpening and use it as a scraper. I usually do this with 357 revolvers id using 38 specials. I have had to use acetone to soften carbon rings occasionally before using the case scraper

[imashooter2]

I’d get a .40 bronze cleaning brush and spin it in a drill motor after letting the chamber soak in an inch of my favorite solvent for a couple hours.

[beemer]

I’d get a .40 bronze cleaning brush and spin it in a drill motor after letting the chamber soak in an inch of my favorite solvent for a couple hours.

I did just that on a 357 that had only 38's fired in it. It would not even chamber a 357. Soaked it in Hoppe's overnight and spun a 40 cal brass brush in the chambers, works like a charm.

[Battis]

SnapCaps bullets are a smaller diameter than the factory ammo, same OAL, and the slide works easily with the Snapcaps. I loaded up a dummy round with a jacketed 124 gr bullet, and the slide stuck. It has to be the chamber. I haven't had the gun too long, and I never noticed that ring until I went looking for it. I got a bottle of C4 carbon cleaner today - maybe I'll let it soak overnight.
I did use a .40 brush by hand, but maybe the drill will work.

[SSGOldfart]

Go to O'Reilly's and get can of Berryman's. Soak a cotton ball in it and push it into the chamber. Leave it overnight. Brush in the morning. Repeat if needed.

has worked for me it's amazing what that stuff can do.

[blackhawk44]

Battis, just to clarify, its a gas-locked, blow back action. In living with my PSP since late 1979, the only parts that I have replaced have been the recoil and magazine spings a few years ago. They just got tired after 40 years. Your description suggests closely checking your extractor and its spring since other than extracting unfired rounds, the P7 will fire and function fine without an extractor. Due to the depth of the chamber flutes, I can't imagine carbon buildup in the chamber creating a problem.
One caution, practice keeping your finger outside the trigger guard while engaging the cocking lever. Should the trigger be held down, intensionally or not, when the grip lever cocks it, it will fire, just like holding the trigger down then releasing the hammer on a cocked single action. Just a caution.