Carbon in revolver cylinder driving me nuts.

[Boxcarman]

Recently picked up a Smith & Wesson revolver and in the process of going over it I've noticed a build up of carbon the the cylinder throats. I've tried everything to try and remover this carbon, carbon remover and let it soak, Butch's Bore Shine, CR-10, Montana, Shooters Choice, etc, etc. (yes, I have a bore scope) I even used a Lewis Lead Remover and twisted it in the effected area and still there's a bunch of lead stacked up. You guys have any suggestions on how to get this stuff out of there? I don't want to go to an industrial penetrating oil for fear of messing up the bluing or etching the cylinder throats. You guys have any suggestions? Thanks. BCM

[HeavyDuty]

I have one of those ancient window screen type bore brushes that I use when all hope is lost.

[jandbj]

Lead remover cloth wrapped around a .40 cal bore brush. Contemplate chucking it up in a cordless drill if it’s extreme.

[Jim Watson]

Never heard of penetrating oil etching metal.
I soak fouled auto barrels in a jar of "benchrest blend", Shooters Choice + Kroil.

[Outpost75]

Soak in Kano Kroil or 50-50 mix of ATF and acetone, leave wet for a week, wet patching daily, waiting patiently! Only after thorough soaking then use .40 cal. bore brush on chambers. In extreme cases in customer service at the factory we used a modified chambering reamer having the cutting edges backed off, so that it would scrape out the lead without scratching the steel. Ultrasonic cleaner will also get it if you have access to one. In the future use soft 8-10 BHN bullets which FIT the cylinder throats, using soft lube such as 1:4 ATF-Beeswax and you won't get any more leading.

[revchuck38]

I’d try a stainless steel CHAMBER brush and see if that works.

If you’re going to shoot lead bullets once it’s cleaned, make sure they’re the right size. The way to figure this out is to drop the bullet (not the loaded round) into the chamber from the rear. It should stick in the throat. If it pushes out easily or slides right through, it’s too small. If you can push it through with some pressure, it’s about right. If you can’t push it through, it’s too big.

Softer bullets with soft lube are best, but even commercial hardcast bullets won’t lead if they fit the chamber throats.

[Malamute]

The larger size brush, like a 40 mentioned above, helps. The proper size bore brushes for the gun in question usually dont have a very good fit in chambers. I sometimes use old 44 or 45 brushes as chamber brushes if I dont want to trash a good one on a smaller chamber.

Old Hoppes No 9 or Shooters Choice has usually done it for me, but when impatient, Ive used the small blade on the Swiss Army Knife to carefully scrape the lead and carbon residue out at a very thin angle. I havent detected any problem doing it but have always been very careful to avoid scratching the chamber wall or step into the throat.

[Boxcarman]

revchuck38, thank you for explaining how to check to see if your bullets are of the proper size. I see people say all the time "be sure your bullets are the right size", but I never knew exactly how to check them. Thank you. I also see that a couple of you have recommended the hardness to be in the 8 - 10 range. If a fellow buys his cast bullets from someone like Montana or Oregon Trail I've seen their advertisements say their bullets are around 15 Brinell hardness. I try to keep my loads around the 700 - 900 f.p.s range, so would the 15 hardness be ok or too hard. This removing lead is a pain in the butt. Once I get it out I want to do all I can to keep it out. Thanks to all for your suggestions. BCM

[Tennessee Jed]

For softer commercial bullets, I believe that Missouri Bullet Co. has lead bullets with a BHN around 12 or so. They call it their "Cowboy" series. I've used many of their bullets from this line and have always been very pleased.

[revchuck38]

Some bullet companies offer “cowboy” bullets that are cast of a softer alloy. I think Missouri Bullets does; I’ve bought from them and have been pleased with the bullets they make. Their turnaround time has gotten pretty long during COVID, I don’t know what it is now.

[revchuck38]

Tennessee Jed - Coke! ;)

[BN]

I've used these stainless chamber brushes for years. https://www.brownells.com/gun-cleaning-chemicals/brushes-amp-bore-snakes/bore-brushes/revolver-chamber-brush-prod1290.aspx

[baddean]

BCM,
Your thread starts out with carbon build up and ends up with lead build up. If it is inside the cylinder just before the throat it's probably carbon. They aren't the same thing and have different causes and removal procedures. You don't mention the caliber of the gun.
Could you provide more info please? Is the gun a .44 mag or .357 mag?
If it is one of these the previous owner may have shot a lot of .44 special/.38 special through it causing a serious carbon build up in the chamber where the shorter case of the specials ends in the chamber. This carbon is difficult to get out likely needing to mechanically remove it by scraping or reaming.
Outpost75 offers the most likely option with the modified chamber reamer.
Malamute and Revchuck options using a stainless chamber brush chucked in a drill may work as well.
Carbon removers work well on lightly affected areas but the carbon you describe has likely been baked on over a period of time and will need to be ground, brushed, or scraped out.
If it's not a .44 or .357 then disregard this as I'm probably full of crap and way off base.
If it's lead build up then the previous owner shot a lot of the wrong sized/hardness bullets in it without regular maintenance and may require mechanical removal as well so you can start fresh.
You may want to determine the size of your chamber throat so you don't have the same issues in the future.

[Boxcarman]

baddean, sorry if I got off base. Here's the latest. We have no more CARBON in the cylinder chambers. I took a thin piece of scotch brite and wrapped it around a worn out bronze brush and after soaking the chambers in penetrating oil for awhile very carefully spun this brush in each chamber for about five seconds with a cordless drill, and then wiped out the chambers and took a look with the bore scope and presto carbon - be - gone. Someone must have shot a bunch of .44 Special brass in this revolver. But now I have another issue. I took about ten 200gr. RNFP bullets and dropped them into each of the chambers. About eight out of ten dropped right through. The other two or so took very little pressure to push them on through. I checked them with my dial calibers and they measured .432" (yes, it's a S&W 29-2 6 1/2"). Now what do I do? I could bump up the velocity so the bullets would obturate more, but that would defeat the purpose of reduced loads for pleasant shooting. Or tell Oregon Trail the next time I need bullets to make me a special run of .434" bullets. Yeah, right. I can see that happening. I do want to thank all of you guys for your helping me with this situation. It's appreciated. I loaded up some Trail Boss, Blue Dot, Unique, 231, Red Dot and Titegroup while the cylinders were soaking today, so if the weather is ok I'll hit the range tomorrow and see how bad it shoots with these loose- in - the - chamber bullets. If you guys have any other recommendations or suggestions please feel free to lay them on me. I need all the advise I can get. Thanks again. BCM

[OlongJohnson]

In extreme cases in customer service at the factory we used a modified chambering reamer having the cutting edges backed off, so that it would scrape out the lead without scratching the steel.

Dave Manson sells that tool for .357 and .44. (https://mansonreamers.com/catalog/)

Best way to check throat diameter and know for sure is to buy a couple gage pins in the size range you think it will be.

https://www.amazon.com/HHIP-4103-0434-Replacement-0-0002-Tolerance/dp/B01BHHOG2C/

https://www.amazon.com/Vermont-Gage-Steel-Tolerance-Diameter/dp/B0006JCMIS/

[baddean]

baddean, sorry if I got off base. Here's the latest. We have no more CARBON in the cylinder chambers. I took a thin piece of scotch brite and wrapped it around a worn out bronze brush and after soaking the chambers in penetrating oil for awhile very carefully spun this brush in each chamber for about five seconds with a cordless drill, and then wiped out the chambers and took a look with the bore scope and presto carbon - be - gone. Someone must have shot a bunch of .44 Special brass in this revolver. But now I have another issue. I took about ten 200gr. RNFP bullets and dropped them into each of the chambers. About eight out of ten dropped right through. The other two or so took very little pressure to push them on through. I checked them with my dial calibers and they measured .432" (yes, it's a S&W 29-2 6 1/2"). Now what do I do? I could bump up the velocity so the bullets would obturate more, but that would defeat the purpose of reduced loads for pleasant shooting. Or tell Oregon Trail the next time I need bullets to make me a special run of .434" bullets. Yeah, right. I can see that happening. I do want to thank all of you guys for your helping me with this situation. It's appreciated. I loaded up some Trail Boss, Blue Dot, Unique, 231, Red Dot and Titegroup while the cylinders were soaking today, so if the weather is ok I'll hit the range tomorrow and see how bad it shoots with these loose- in - the - chamber bullets. If you guys have any other recommendations or suggestions please feel free to lay them on me. I need all the advise I can get. Thanks again. BCM

BCM
Glad to hear that you got the carbon out.
As to the other issues, I assume that you mean you checked the chamber dimensions and found .432 which according to SAAMI is correct. (.4325)
If you are using the Oregon Trail 200gr bullets they show a hardness of 15 on the BS. That's not hard. Sized to .431
https://oregontrailbullets.com/xcart/?target=product&product_id=50#product-details-tab-description
Missouri Bullet Co sells a .44 cowboy bullet that's a little softer at 12 BS sized to .430
https://missouribullet.com/details.php?prodId=238&category=5
The lighter you want to make the load the softer the bullet you want to use.
If you are going to continue to shoot .44 special in the gun you will always get a carbon ring in the chamber. Just clean the chamber well after each session and you won't get the hard build up.
It will be interesting to hear how your different loadings work out for you. Small subtle differences in powder amounts can make a big difference in bullet performance and leading with minimal effect on felt recoil.
If you're not recoil sensitive standard .44 special load data (with subtle adjustments) should work for what you are looking for in that gun.
Remember that just because these bullets were loose in the chamber when you dropped them through doesn't meant they are still loose when fired under pressure. If the chamber is .432 and the bullet is .431 it will drop through.

[OlongJohnson]

Another thing that may help is cleaning the cylinder while the gun is still warm at the range.

When shooting my GP, I take some paper towels in the range bag. Wipe it down immediately after shooting, while it's still warm, and the vast majority of the soot comes right off with a gentle wipe and no chemicals. Wait for all the carbon deposits to cross link and adhere to the steel as they cool, and there will be scrubbing and/or chemicals required.

[Tennessee Jed]

But now I have another issue. I took about ten 200gr. RNFP bullets and dropped them into each of the chambers. About eight out of ten dropped right through. The other two or so took very little pressure to push them on through. I checked them with my dial calibers and they measured .432" (yes, it's a S&W 29-2 6 1/2"). Now what do I do? I could bump up the velocity so the bullets would obturate more, but that would defeat the purpose of reduced loads for pleasant shooting. Or tell Oregon Trail the next time I need bullets to make me a special run of .434" bullets. Yeah, right. I can see that happening. I do want to thank all of you guys for your helping me with this situation. It's appreciated.

If you guys have any other recommendations or suggestions please feel free to lay them on me. I need all the advise I can get. Thanks again. BCM

Yup, I've been down this road. I inherited an early 1980's S&W 629-1, and couldn't figure out why I often had leading issues, until getting some pin gauges and measuring the cylinder throats, and realizing that they were all 0.432". I later learned that most 29's and 629's made prior to the mid - late 1980's all had that size throats. I've read that after the late 1980's, S&W reduced the size of the throats to around 0.429 - 0.430. The problem, as you've noticed, is that most commercial casters are focused on guns manufactured after then, so their bullets are 0.430 wide.

So far, my solution has been to purchase bullets from makers that will cast bullets at 0.432. That includes moyerscastbullets.com, and gtbullets.com. Bullets from both entities were fantastic, and going with the wider bullet made the leading disappear completely.

Other options I'm considering, but haven't tried yet, include trying to find cast bullets sized at 0.431 a bit more on the soft side (like bhn around 12 or so), hoping that the bullet will obturate fully. Or checking with Missouri Bullet to get their 0.430 bullets unsized, hoping that unsized they're closer to 0.432, but if they're over 0.432 I might have to size them, and I will definitely have to lubricate them.

The best option, though, will be get into casting and make the bullets myself. I'm not there yet, but I'm considering it.

One thing I strongly suggest is to stay away from undersized bullets that have a poly or moly or Hi Tek - type coating. When the bullet is undersized and that coating gets smeared in the barrel, it's much more work to get that out of the barrel than just regular leading.

[Boxcarman]

baddean, what I mic'd was the bullets. I don't have a set of go, no - go gauges to check the chambers, but if the bullets fall through at .432" what are the chamber dimensions?? One more question, if I get a plug gauge and lets say the chambers are in fact .432" what is the ideal cast bullet to run in this gun? .433" or maybe .434"? I don't know, I'm asking. Let's say for talking purposes the chambers measure .432" and .433" is the ideal size for this gun, would that also apply for a .38 / .357 magnum also? One thousandth over chamber size? And my wife's .32 H&R magnum/ .327 Federal? One thousandth over again? Does caliber have any effect on bullet to chamber size?
I'm going to shoot the loads I mentioned and if your interested I'll post the results. Thanks to all once again for your help. BCM

[OlongJohnson]

As I understand it, the starting point is the barrel groove diameter.

Slug the barrel. Cast bullets should be ~0.0005 to 0.001 inch larger than that so they seal very well and are guided precisely and consistently down the bore the same way every time.

The bullets should be a slip fit or very slightly undersize in the throats. Like +0.000/-0.0005 inch in the throats. You don't want the bullets to be larger than the throats, because then you are using the cylinder as a sizing swage every time you fire it, which will quickly lead to end shake. But you don't want clearance around the bullets, because then the charge gasses flow past the bullets, melting the surface of the lead, and coating the throats, forcing cone, etc. with molten metal.

If your throats are too small, you can get them reamed/honed up to the size they need to be.

If you throats are too large, you can become familiar with the Lewis Lead Remover or shoot jacketed bullets.

[revchuck38]

If your groove diameter is .429 and you size your bullets .430 but have .433 throats, you’re probably going to have leading. The reason the +.001 thing usually works is that properly sized throats are .001-.002 over groove diameter and most S&Ws held to those specs. M25-2s were notorious for having .451 groove diameters and .454-.455 throats. I didn’t know about the 29-2s but apparently that’s the case. Elmer Keith didn’t have to worry about this because any M29 S&W sent him would’ve been gone over with a fine-tooth comb to ensure it was within specs for use with cast bullets.

Back in those days, Smith could sell every M29 they made due to the Dirty Harry movies. Most of those guns, if they were shot at all, were shot with jacketed factory ammo, so leading wasn’t an issue. If you raised the leading as a warranty issue, chances were good that S&W would claim that the warranty was voided by the use of non-factory ammunition.