Barrel leading in 44mag

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edfardos

New member
I just tested out a new S&W model 69 (4" 44mag), and noticed barrel leading with all bullets and all velocities. I understand the BHN/velocity/obturation theories, but I just thought I'd check here if anyone else saw similar results.
I can insert a .429 plated bullet in a charge hole with finger pressure, and possibly tap through with a cleaning rod. .430/.431 bullets would need a mallet.

Lead streaks appear in the grooves and lands in the first inch of the barrel, even after just one round. A choreboy brush quickly removes it. I use the same Oregon Trail Laser Cast (albeit at higher velocities) in a Ruger Super RedHawk with minimal or no leading.

Oregon Trail Laser Cast .431 BHN=22
7.4 hp38 = 941fps lead
7.7 hp38 = 973fps lead
8.6 hp38 = 1069fps lead
9.1 hp38 = 1099fps lead
17 2400 = 1154fps less leading
18 2400 = 1204fps inconclusive

Misourri Bullet Company .430 BHN=18
8.6 hp38 = 1067 severe leading

Xtreme plated, .429
8.6 hp38 = 984fps lead, plus bits of copper plating welded in the grooves



Any ideas? Charge holes too small or barrel too big? The forcing cone on this is very short, and lead starts immediately in the grooves after the cone.


thanks for any hints, or other combos to try!

best,
--edfardos
 
I have one on the way so I'll keep a eye out for leading. I mostly shoot jacketed bullets in anything over 357 mag but I have some laser cast I may load up. What powder are you using? Maybe faster powder has more leading.
 
HP38 and 2400 is what I've tried. They cross over at about 1150fps. I've always used max load of H110 in the redhawk, but I'm not going to try that in this little model 69.

thanks,
-edfardos
 
Check your cylinder throats if you can push thru a soft slug. My 629 measures only .4285. My best guess is that those bullets are being swaged down in the cylinder, but are then too hard to expand to fill the grooves properly as they enter the barrel.

FWIW, I'm running Hornady swaged 240 LSWCHP .430dia.(probably around 8BHN) at around 925fps with no leading at all in my 629. I'm guessing that you shouldn't need more than 12-16BHN to reach 1200fps or so, if your measurements are similar.
 
It could be one of several things. As springer says, check your cylinder throats and your forcing cone. Ideally, the bullet should be 1/1000th over throat diameter and the forcing cone should be 1/1000th smaller than that. You want that bullet to have a good seal as it goes through both the throat and the forcing cone.

Bullet hardness has to match your speed. Pushing soft lead bullets to magnum velocities is a sure-fire cause of leading.

Where the leading is found is an indicator. If it's up near the throat/forcing cone it indicates that you have a size problem. If it's near the muzzle, that indicates that your lube is insufficient. If it's all the way down the barrel, it's an indication of insufficient harness.
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BnH 18 ought to be hard enough to push to magnum velocities, so I'd suspect a size problem.
 
Thanks guys,

I don't have tools to do more detailed analysis.

The throats are likely .429" as it takes some mild tapping to get a plated bullet measured at .429" to go through.

Lead is strictly in the first inch of the barrel, immediately after the cone.

The 18bhn bullets at .430" had severe leading, tested at 1000fps.
The 22bhn bullets at .431" had consistent leading from 900 to 1100 fps.
(these bullets might have cleaned up a bit when i switched to 2400 powder and pushed them to 1200fps)

The plated bullets are a disaster in this revolver, and my redhawk. The plating comes off and sticks in the grooves, followed by severe leading (swaged core).

So I've tried various sizes and hardnesses, and velocities, and powders. I'm just looking for a next step. It's not horrible, but I'd bring a chore-boy brush with me every time to the range to do any serious target work.

thanks for any next step suggestions!

--edfardos
 
I was shooting 310 grain cast bullets from Liberty with my Ruger 44 mag carbine semi auto. Then I shot some 240 gr JHP, and the muzzle peeled back like a banana.
I could see the bore was full of Leading.

This is 15 years ago. The guy who fixed the rifle has passed away. The guy who cast the bullets has passed away.

attachment.php
 
wow, like a bugs-bunny rifle explosion?

In any event, i'm monitoring lead levels in the barrel and just a few swipes of the chore-boy-wrapped brush cleans it all out. But even after just two cylinders, I have a shiney disc of lead dust under the firearm.

It seems like there's lots of lead on the cylinder face too, more than I've seen on other revolvers anyhow.

So, next steps, based on your suggestions, try a smaller diameter cast bullet? something that's just 1/1000 bigger than the throats? xtreme makes a hard-cast .429 I've been wanting too try. My .431" and .430" cast bullets don't seem to be working.

thanks,
-edfardos
 
edfardos said:
Lead is strictly in the first inch of the barrel, immediately after the cone.
Click to expand...
I have been told, but have no definite experience, of a slight constriction of the barrel under the barrel threads. Sometimes, torquing the barrel causes a constriction under the threads. Slug your barrel with a soft slug from the muzzle to be sure.

The plated bullets are a disaster in this revolver, and my redhawk
Click to expand...
I don't like using plated bullets at magnum velocities. Some folks report good results, depending on the brand of bullet, but I've always either used hard-cast lead with good lube, or conventionally jacketed bullets. That's just me, though. YMMV.
 
Last summer I bought a new 629 Classic 5" bbl.

It leads up fiercely with Special rounds (I only load jacketed for Magnums). I think the barrel is scruffy.

I may firelap it. Or not. Haven't decided yet.
 
Just out of curiosity, how does it shoot and what's the accuracy like?
Accuracy or the lack of it can be a helpful clue sometimes in solving this kind of mystery.
 
In my experience throat to groove diameter is more important than hardness. For example, if the groove diameter is .430, your throats need to be 15/10,000 over the groove diameter or .4315 to shoot a .431 lead bullet.

The groove diameter of your revolver determines the bullet size, the throat diameter, if not 15/10,000 over needs to be reamed to that.

Most revolvers have a 5 degree forcing cone. Having it cut to 11 degrees helps but is not as important as the bullet, throat, groove relationship.

I have a .41 mag that I have pushed a .411 bullet cast from wheel weights to 1350 fps with good accuracy and no leading. The throats on that Blackhawk are .4115 and the groove is .410. the forcing cone hasn't been cut it is still at 5 degrees.

http://rugerforum.net/library/19869-lead-bullets-revolvers.html is a very good read on revolvers and lead bullets
 
Accuracy is spot on (five inch groups at 30 yds is good for me).

Since this was a brand new revolver and I was working up test loads, I noticed the leading immediately (visually) and cleaned every other cylinder. I also got the impression that the leading wasn't getting worse after each shot, and my groups didn't really open up just before cleanings.

I still have no clue.

Best guess is barrel restriction at the threads. Undersized throats, or I'm not pushing hard bullets fast enough. Lots of pseudo-science out there, so I'm mostly doing trial and error. I may bump up the load on the 18bhn .430" bullets, and/or buy some smaller diameter 18bhn .429" bullets.

thanks again for all the hints. The leading isn't severe, but infinitely more than my super redhawk gets (It has bigger throats and can take full pressure loads fwiw - the .431" 22bhn bullets work flawlessly in the big redhawk). The other thing I don't like is that I'm trying to use a fast powder (win231) to get low-magnum speeds (1100fps).

For those of you who discovered the perfect non-leading load, do your bullets push through your cylinders with finger-strength? fall through? require a dowel and hammer? My perfect-load for the redhawk requires a very light driving to get a .430" bullet through the cyls. This new S&W would require a very hard driving to get the same bullet through it's cyls, so I'm thinking of downsizing, as this is all trial and error at this point.



--edfardos
 
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Bullets should "nearly" fall through the throats. Very light finger pressure only. The throats are just suppose to get the bullet lined up with the forcing cone without swaging down the diameter. Then the bullet needs to be 1/1000th bigger than the groove diameter when it hits the groove to seal off good.
 
"I can insert a .429 plated bullet in a charge hole with finger pressure, and possibly tap through with a cleaning rod. .430/.431 bullets would need a mallet."

There's your key I think. Going to a bullet any larger than .430 probably won't make any difference, regardless of the alloy. They'll all end up at the throat diameter when then enter the forcing cone. If that diameter is less than the bore groove diameter, and/or the alloy is too hard to obturate up to bore diameter, you're going to have some leading. Try loading some higher velocity loads with your 18BRN bullets and that may reduce the leading as the higher pressures will help to seal the bore better.
 
I have only shot jacketed in my 44magnum. It will take some relatively hard lead to stand up to the .44magnum velocity. I would try jacketed bullets and see if you have a copper fouling issue. If so, then you know you have a barrel problem. If not, then you know your lead bullets are simply too soft.
 
I am not a gunsmith and most of my ‘knowledge’ comes from my friends at the range and hanging around here. FWIW I’d take advice from the folk that have posted here before this post.

I’m just going to summarize what they have said and para phrase it and if I misrepresent what they said please feel free to correct me.

First off though, before you do any work on the gun itself I’d take it to a real gun smith or send it back to the factory. It’s a new gun. They should take care of you. Please don’t think I’m telling you to take reamers or any kind of abrasives to your gun. I’m not.

1. Bullets may not be right size.
2. Bullets may not be hard enough.
3. Bullets may not be lubed enough.

These issues are discussed in a pretty good Youtube video here:
https://www.youtube.com/watch?v=8VNjn9aIlWY

4. The cylinder throats might be uneven or too tight. A video on reaming a cylinder is here but I’d say don’t do it yourself, send it back to the factory or get a professional to do it.

https://www.youtube.com/watch?v=YZK1GRUR3xE
also here:
https://www.youtube.com/watch?v=FTb9cNKNavQ

If you think the problem is barrel restriction at the threads you should feel the constriction if you slug the barrel. The slug will take a certain amount of force to be forced down the barrel and that force will noticeably increase at the barrel restriction.

Once again this is just summarizing what’s been mentioned before in this thread.

Good luck.
 
BHN of 22 is to hard for 1000-1200 fps. Could be the cause of some of this issue. 15-18 is a more appropriate range.

That doesn't explain why you are leading at 950fps with a bullet of 18bhn. What kind of lube are you running and how much?
 
Nothing necessarily new here beyond what’s been stated, but based on what you have reported, I would say:

You need to be using .429 or possibly .430 lead bullets if the cylinder throat is .429.

There may very well be a barrel constriction at the threads where the leading is occurring.

You can try to send it back, but don’t be surprised if the manufacturer doesn’t address lead bullet performance if the gun works well with factory jacketed ammo.

If you’re not interested in sending the gun back at this point, I’d first try some softer bullets around BHN=11, sized to .429, with a good lube like Alox, pushed to around 1000 fps. If you get leading with that, it’s likely any combination of lead bullet velocity and dimension will lead the barrel.

Next steps would be making sure the forcing cone is relatively smooth, and removing any barrel constriction that exists.
 
Edfardos,

Back when good revolver custom smiths were more common (because more revolvers were shot in competition) about the first thing they did by way of an accuracy job was ream the chambers to maximum. I bought a Redhawk in the 80's that would shoot touching holes at 50 yards. My chamber throats were about .431". A friend was so impressed he bought the same model. His would barely stay on a paper plate at 25 yards. So, we sent it to Ruger. Six weeks later it came back with a shop note saying they had reamed the chambers. It then shot very well, too.

So, if you can get the factory to ream the cylinder to address your problem, that's the way to go, as they can check and replace anything else they thing may be an issue at the same time. They can also make sure the finish is still matching when they are done (more of a problem with blued guns than with stainless, though). It's probably the first step to take, no matter how you get it done.

The bore constriction is next in importance, though you may want to address it first. Before you do that, you want to slug the bore to feel for such a constriction. If there is one, you can firelap it out with abrasive-impregnated bullets of about BHN 11-12 hardness, using a very light powder charge (like two or three grains of Bullseye). You can search the forum for threads on both slugging and firelapping. There are kits for both processes available, if you need them. Firelapping will slightly open the throats at the same time as it clears the throat constriction and smooths the bore surface, which is why you want to do it before getting throats reamed, assuming you still need to afterward.
 
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