Leading in cylinder mouths and forcing cone in S & W 686

[hunter74]

Looking for advice regarding leading in cylinder mouths and forcing cone. The barrel is free of leading but I can't get the SWCs to perform. The accuracy is really bad. The boolits is sized to .358 and that's the diameter I have allways shot, but earlier I've used comercially produced hardcast.

The problem load is 3 gr Clays behind NOE 360477 Keith style SWC. I've also tried VV N320 but with the same result. Bad accuracy and severe leading.

Because of the lead free bore I guess the sizing of the boolit is right for the bore, or? The barrel is slugged .3573 but I have not yet slugged the cylinder.

The strange thing is that the Lee 125-RF boolit does not lead in .358! This got me thinking, if the problem was skidding or bad engraving of some sort. I guess the RF design makes the rifeling grip the boolit easier than the sharp shoulder of the SWC design, right?. Comments?

In my mind two things need to be tested:
1) Slower burning powder to make an easier start for the boolit. I'm thinking about trying HP-38, N340 and Longshot. Aveilible powders are the ones from VhitaVhouri and Hodgdon.I use longshot in my 9mm loads with the same alloy without leading in .357. Strange that the 38 is more troublesome to get working than the 9mm loads :)

2)Sizing to .357. Maybe the boolit is too big and get "shaved too much". This is last resort. I kind of doubt this is the problem, but anyways.....

Oh...my alloy is range scrap with a hint of tin added. They hold about 10 BHN, measured with Lee hardness tester.

Thoughts about my reflections.....I'm interested in other suggestions also because I'm soon desperate. It must be possible to get SWCs to shoot in a revolver for me too :)

Edit: I shoot mostly 38 special for competition in my 686. Thought I should mention it.

Thanks!

[ku4hx]

I have not yet slugged the cylinder. You need to do this or at least drop sized boolits into them and check the fit to see if they fall through or you have to drive them through.

[Vinne]

Each gun has a personality of it's own. One gun with a following serial number will not shot the same load as the one ahead of it. You have to work up a new load any time you change any component. Even change in case length could effect your group.

You may be on the right track with a change to HP-38 or W 231. Also try bumping up the load one or two tenths.

Hope this works for you. Let us know what works.

[Larry Gibson]

Oh...my alloy is range scrap with a hint of tin added. They hold about 10 BHN, measured with Lee hardness tester.

Range lead is many times rich in antimony with little to no tin, especially if a lot of the alloy was out of jacketed, .22LR or commercial cast bullets. I use a lot of it myself. I find it makes a lot better alloy if you dillute the antimony by adding 20 - 30% pure lead and then add 2% tin to that.

Also I did not see any mention of the lube you are using?

I shot a lot of Lyman 358477 150 gr SWCs over 3.5 gr Bullseye 38 SPLs in my duty M15s (4 & 5" barrels) in PPC, TRC and IPSC matches not to mention since my competition days.

Larry Gibson

[hunter74]

You need to do this or at least drop sized boolits into them and check the fit to see if they fall through or you have to drive them through.

I have tried to push. 357 sized boolits through with a pencil and just finger power, and no chanse! I had to use a rod and a hammer to get them out the same way I pushed them in, so its safe to say that the throats are smaller than 357 i guess.


Tried to get a measurement of the throats whith my calippers but an exact measurement was hard, so I don't relay on the numbers I got but they were in the range of 354-3555

[hunter74]

The range scrap I use is mosly 22s and jacketed 9mm. I have tryed homemade lube, orange magic and carnuba red, and the results are the same, so I don't think the lube is the problem, or am I wrong? My home made lube is soft and the other two fairly hard.

It can't hurt to try 3.5 gr with HP-38. I suspect Clays to be too "hot" and fast. I have not tried to "bump up" my 3 gr load of Clays since I've used 3-4 gr of N320 with bad result. 4 grs is on the stiff side. The burn rate of N320 and Clays are similar and mye results with N320 where as bad as with Clays.

I also tried 2.5 gr of Clays with Lyman 148 WC load today with the same bad leading as a result. It was sized .358 with orange magic. Isn't this a fairly "standard" target load? Strangely all of my casted boolits lead this way, unless the Lee 125-RF loaded with 4.4 gr N320. An easy "fix" is to use that load only but I hate to give up, since the NOE '477 mould is a dream to cast wit, and they make a nice pile real fast!

[cbrick]

Forget trying to get measurements for this with calipers least of all round holes with flat faced calipers. Calipers are plain and simple not accurate enough, they weren't designed or ever meant for this level of accuracy.

If needed to get accurate throat diameters have a smith do it for you. The boolits need to be a mild snug fit in the throats. It's doubtful the throats are smaller than the groove diameter, if they were bore leading would be a certainty. Revolver throats are the world's best boolit sizer, doesn't matter in the slightest how much bigger you make them they will be throat diameter when they exit. If you measured a bore slug with your calipers there is no way for us to know what the actual diameter is.

Larry mentioned lube but you said the bore does not lead up, only the throats. Lube will have nothing to do with throat leading.

If the front edge of the driving band of the chambered cartridge does not reach into, start out already in the throat the cartridge will lay at an angle in the chamber, when fired the low side of the front band will strike the rear edge of the throat and shave lead. This causes throat leading, continued shooting will spread the leading onto the forcing cone and further shooting spreads it into bore. This has nothing to do with sizing, it's the short over all cartridge length where the laying at an angle in the chamber where the center line of the boolit is not lined up with the center line of the throat/bore. The SWC could possibly be worse than the round nose because of the sharper edge of the front driving band of the SWC.

Rick

[JSH]

Shooting 38's in a 357. Try same load and bullet in a 357 case. I know this will make a whole bunch of folks holler. But I know what I have found.
FYI I was of the mind set that it was just the modern SW that had these issues. Some of the guys I run with had the same issue with early 357s. Didn't seem to be near as bad though with the dozen or so revolters we fooled with.
Jeff

[hunter74]

If short COL is the cause of the lead shavings and the related problems, it could work to set the boolit farther out in the case, am I right? Since this boolit is long this is posible even in 38 special cases. In these light loads my experience is that roll crimp not is needed. I light taper crimp could be applied to the boolit without sizing it down and obtain a much longer COL, and thereby obtain better allignment in the cylinder.

Guess I have more things to try out. I'll let you know how it turns out! Thanks! Great advice as allways on this site :)

[44man]

You really need accurate measurements of the throats and groove.
Remember most S&W's are 5 groove, makes it harder.
There is a chance the throats are too small.
I am going to agree with Cbrick.

[MtGun44]

Make sure you are not sizing down the boolit as it is seated. Seat one and
pull and then check diam with a micrometer. Calipers are only accurate
+/-.001 and can leave you guessing. If you pull one and compare it to
a non-seated boolit, you will likely have a good comparison, but not
absolute numerially correct value.

Agree that you cannot measure throats with a caliper, instrument is not accurate
enough and unsuited to the task. Pushing the round thru is accurate,
so see if one seated and then pulled is undersized.

Bill

[44man]

Now I can measure with calipers to .00000000001"! :kidding:
Really need a good mike.

[462]

Make sure you are not sizing down the boolit as it is seated. Seat one and
pull and then check diam with a micrometer.

This should always be the first step, whenever troubleshooting a leading problem. Sadly, it is all too often overlooked. My experience is that a seating die can swage a boolit . . . especially if its' a Lee handgun seating die.

[Tom Myers]

Why don'tcha just drive a slug through each throat and then measure the slugs to find each throat diameter?

Also I have noticed that if even a slight amount of lead is shaved while seating bullets, that little bit of lead will be deposited in the forcing cone and start an ongoing leading process in the forcing cones and throats.

[runfiverun]

couple of things to try.
try the load in 357 brass if possible.
try water dropping.
lower the load a little.
you might have rough cylinder throats.

off the top of my head 3.3 grs of clays in a 357 case is close to or is max.
might be remembering wrong.
I have pushed the 358477 with the 3.3 [clays] load and lowered it in a 38 case sized to 358.
your load is low in velocity but not so low in pressure.
your round shouldered boolit working is showing the difference in design, nothing more.

[cbrick]

Make sure you are not sizing down the boolit as it is seated. Bill


Make sure you are not sizing down the boolit as it is seated. Seat one and
pull and then check diam with a micrometer.


you might have rough cylinder throats.

Is it just me? Am I missing something? The OP said his bore is clean. The OP said nothing about forcing cone leading or a rough forcing cone. He said the throats are leading with a SWC and that has nothing to do with sizing down while seating, a rough forcing cone, thread squeeze in the frame, trailing edge leading, poor lube or blow by from a small boolit. His leading is before any of these places or causes.

The only way I have ever been able to cause throat leading was by using a SWC that did not have the front driving band seated inside the throats with a mild snug fit when chambered. The boolit (the whole cartridge) lays at an angle in the chamber, even in the tight chambers of the FA revolver this happens and if the chambers are loose it's worse. When the cartridge is fired the boolit instead of being aligned center line of the throat and bore is already at an angle downward. The front edge of the front driving band shaves lead as it finds the throat and is pushed up and into the throat.

The following picture is a prime example of this except in this case it's the center driving band that strikes the inside edge of the throat because it is a two diameter boolit and the front driving band is too small to align it in the throat. These boolits have been sized but notice the front band wasn't touched. These boolits lead up my FA 357 throats something terrible while leaving the forcing cone and the bore spotless unless I keep shooting, in that case the leading spreads to the forcing cone and then the bore. These are also the least accurate boolits I've ever fired in my FA's. They may well work fine in a rifle but in a revolver they are both real skunks.

71864

I almost fire lapped a S&W 44 Spec thinking barrel restriction until I noticed the leading started in the throats and I tried a boolit that properly fit inside the throats when chambered, all leading stopped instantly.

Rick

[cbrick]

I just re-read the original post, he did say forcing cone leading in the title but not in the post. Same effect and cause though, the lead had to start in the throats and spread to the forcing cone. Continued shooting will spread it into the rifling. The leading could not possibly start on the forcing cone and spread to the throats.

Rick

[hunter74]

I tried to pull a boolit today just to get one more thing out of the way. I was not able to do this with a pair of pliers and my press, that boolit was sure seated firm in the case even without crimp. Any advise? I'm not able to get a grip firm enough with the pliers on the narrow nose on the swc. Im aware of the collets and bullet puller dies, but this is not working on SWCs, is it? Maybe a noob question but, there it is

[cbrick]

Try this . . .

Frankford Arsenal Impact Bullet Puller (http://www.midwayusa.com/product/215517/frankford-arsenal-impact-bullet-puller)

What are you using to expand & bell the brass?

Rick

[hunter74]

Bullet puller ordered :)

I reload on my Dillon XL650 so it's the powder funnel for the powder measure that bells the case mouth. I notice that this is a lot shorter than my RCBS expanding die so I'm thinking about screwing that into station 3instead of the powder checker. If the boolits gets sized down the problem is not enough case expantion or the RCBS seating die is swagging the boolit down. I also have a Lee die that I could try.

But...it's strange that the bore is lead free if this is the case. It's just the mouths and forcing cone that gets leaded.

[cbrick]

Well Hunter, you may have a problem with brass tight enough to size down the boolits but . . . You said the bore isn't leading and even if this is happening it wouldn't cause the throats to lead. If it did every bevel base boolit ever shot in a revolver would lead the throats.

Boolits too small because of tight throats, sized too small or sized by seating in the brass will allow blow by and bore leading beginning on the trailing edge of the rifling. Again, you didn't mention any bore leading.

Rick

[hunter74]

I just want to report my latest discoveries.

Since I’m tired of scrubbing my revolver lead free I did many changes at once for tomorrows range session.
1)I screwed the RCBS expander die in station 3 of my Dillon press. I used it to expand a case and hammered gently a boolit down to the right seating depth, pulled the boolit with pliers (Now it works! The boolit sits a bit looser). The good news is that the boolit did not get swagged down.
2) Seated a boolit with the seater, and the boolit came out right here also, so the problem isn’t the seater die either.
3) Pulled a boolit after it was runned through station 5, the taper crimp die, and the boolit came out right.
All god news so far!
4) Changed powder to HP-38 and loaded up some rounds with 4.0 gr behind the 360477 sized .358 seated with a light taper crimp in the crimp groove.
5) Loaded up some rounds with 4.0 gr with the same boolit also sized to .358 but with a longer COL to shorten the jump into the mouths and hopefully get better alignment in the cylinder. I seated the boolit as far out as possible. The case mouth was right under the grease groove. Col = 39,92mm (1,5717””)
Both of this testing loads was loaded in 38 special brass since I have buckets full of them, and my 357 cases all are loaded with hardcast purchased bullets.

Looking forward to tomorrows range session. If this does not work I guess the only thing left to do is to free up some 357 Magnum brass. I’ll report back soon. Hopefully someone else also could learn something from this.

[detox]

In the latest issue of Handloader magazine there is an article written by Mike Venturino about shooting cast boolits in .38 S&W revolvers. He used soft 20/1 lead tin alloy and light smokeless powder loads. He stated that bullseye powder was most popular for this combo, but he had none on hand for the test. He tested several smokeless powders and cast boolit designs. He used the soft SPG lube.

I believe he also stated he will doing a future article on Trail Boss smokeless powder.

[hunter74]

Report from today’s range session. I’m afraid there is no good news, the results were still exactly the same as before. Severe leading in the cylinder mouths.

Today’s test loads:
4.0 gr HP-38. - 150 gr NOE 360477 seated in crimp groove in 38 special brass, sized .358
4.0 gr HP-38 - 150 gr NOE 360477 seated long, (1.5717””) in 38 special brass, sized .358
3.0 gr Clays. - 150 gr NOE 360477 seated in crimp groove in 38 special brass, sized .357

There was no difference on leading if the boolits were sized to .357 or .358. The load were the boolits were seated long, the load clearly was too weak. It was a lot of unburnt powder residue in the case and in the barrel. A clear sign of too low pressure.

Before I give up I want to try two more different things.
1) Bump up the load to 4.5-5.0 gr og HP-38 and continue to seat them long I 38 brass
2) Use a bit stiffer load in 357 Magnum brass and see.

If this doesn’t work I don’t know what to do besides to use another boolit or take a trip to the gunsmith.
Thaughts anyone?

[ku4hx]

I don’t know what to do besides to use another boolit or take a trip to the gunsmith.

Over the last 40+ years of casting, loading and shooting I've learned a few things, but one that I relearn periodically is that some guns are simply picky eaters. I'd venture a guess that yours falls into that category. If you have a load that works, you might want to go with that. Or you could try a different SWC boolits, powders, charge weights and so forth.

Given your posts seem to indicate your throats are much smaller than your bore, a trip to a smith knowledgeable with Smith revolvers may be your last resort. But if it were me, being an old fart, I'd stop fighting that "bad boolit" for a time at least and try something else. Some guns are like old men ... picky and cantankerous.

[hunter74]

I hear ya, but the problem is that I have the exact same problem with another SWC, the Lyman 358456.

I've also shot tens of thousands of SWC's over 10-15 years earlier. It have been purchased hardcast. (BHN aprox 18-22)

[ku4hx]

I hear ya, but the problem is that I have the exact same problem with another SWC, the Lyman 358456.

I've also shot tens of thousands of SWC's over 10-15 years earlier. It have been purchased hardcast. (BHN aprox 18-22)

I know what you're going through. But that just strengthens the "picky eater" comment. If your gun doesn't like two SWC designs, then that tends to tell me your gun simply doesn't like your SWCs at all. Is there a mold out there somewhere it likes? I got no clue. But if you keep getting bad results with all your SWCs you've tried and getting good results with other profiles and others boolits, as odd as it might be, I'd go with the "does not like" your SWCs at all.

I stopped casting a 40 cal SWC design for that very reason. I had three guns and five barrels that simply would not feed the design. I had one gun, an S&W by the way, that fed it fine. I refuse to cast two boolits when one should work. My solution was to ditch the SWC design and go with a true truncated cone. Kind of POed me I had a perfectly good six cavity mold I retired, but such is life.

[Mal Paso]

I would measure the chamber and throat diameters. I'm guessing one or both may be oversize.

Try a .360" boolit.

Get a Lewis Lead Remover (Brownells). That way you can Smile while you experiment.

My contention has been, leading that is hard to remove was deposited by gas cutting. A tighter fit will reduce the gas escaping past the boolit and the gas cutting.

BLT reported the same problem with his 625 and a .002" larger boolit cured it.

[Sensai]

Have you tried just pushing the boolit through the cylinder by hand? I could be wrong, but I think that you'll find that it goes through without any resistance. Try it back to front and front to back. I think the throats are too big for the boolits.

[hunter74]

I cannot push a 357 boolit through!

[Sensai]

Well, that shoots that theory !

[detox]

If this doesn’t work I don’t know what to do besides to use another boolit or take a trip to the gunsmith.
Thaughts anyone?

Be sure to remove all lead. Use .357 Magnum brass, soft alloy and SPG lube

[gefiltephish]

My wife shoots NOE 155 WC's (3.1gr TG) in 38 cases from her 4" 686. It leads the forcing cone a bit, but not usually real bad. She may shoot 50-100 rounds per session. The rest of the barrel is pristine except for powder residue. The throats never seem to build up beyond an initial very thin coat of lead. At the end of each session I fire 2 gc'd 357mag rounds and it cleans out the lead as sweet as can be. If I feel like it, I'll zip a dry patch through once and find the bore is like a mirror. My own 686 (6") and 64 are the same way. I usually shoot this bullet (http://accuratemolds.com/bullet_detail.php?bullet=36-160H-D.png) in 38 cases.

BTW, all 3 barrels slug to .357 (mic'd) and I had to open a few throats a smidge so the bullet would juusst push through. I keep trying to convince myself to size the bullets to .358 and then match all the chambers, but since the bore doesn't lead and the gc's clean out what little there is in the forcing cones, I may just leave well enough alone. However, in the back of my mind I'll always wonder if couldn't eke out a tiny bit better accuracy - but I figure nah, I'm the most inaccurate part of this equation anyway.

[fredj338]

Sounds to me that your cyl throats are way to small. I am surprised you are not getting some early leading. IMO, you can
t fix that with a bullet, but only by having the throats opened. I have no idea why the lighter/shorter bullet isn't leading, unless it's because the bearing surface is shorter?

have tried to push. 357 sized boolits through with a pencil and just finger power, and no chanse! I had to use a rod and a hammer to get them out the same way I pushed them in, so its safe to say that the throats are smaller than 357 i guess.

Tried to get a measurement of the throats whith my calippers but an exact measurement was hard, so I don't relay on the numbers I got but they were in the range of 354-3555

[hunter74]

Slugged a 358 sized boolit through the cylinder and it came out .3573. Not to bad I guess. Strange that .358 should lead as bad. A little worried anywas because last time i measured the bore also measured .3573.

[outdoorfan]

My 686's throats were in the .3562-.3565 range. The 358477 with 25-1 alloy sized to .358 and pushed by 7.5 grs Unique doesn't lead one bit. That same boolit in front of 3.2 grs Red Dot or 3.8 grains Unique doesn't lead either. This is in .357 brass.

I didn't read the whole thread. Have you tried those boolits in 357 brass?

[Mal Paso]

My 629 had throats smaller than the .429 bore. S&W told another forum member they cut the throats for jacketed ammo. That seems to mean small throats. I never had any throat leading but accuracy with 44 Specials was poor until I reamed the throats. I cut them a hair over .431" ( SAAMI is .4325" ) and Special accuracy improved dramatically. I think there is a 357 throat reamer, on loan, making the rounds of this forum.

I am curious what your chamber size is. It should be no larger than .381" and brass .010" x 2 allowing a few thousandths for the boolit to escape. The SAAMI spec for 38/357 throats is .358".

You are the third person to report throat leading this year and stump the forum. Here is the SAAMI Drawing for 357 Mag.

[Larry Gibson]

Hunter 74

That .22LR and 9mm range alloy is heavy in antimony and deficient in tin; add 2% tin.

Use a good soft commercial lube like BAC or Lar's 50/50 NRA formula.......even LLA. The throats are fine as is your sizing at .357 or .358. It is the antimony rich alloy and the lube.

Larry Gibson

[mroliver77]

Do you have any other alloy? Any pure lead to add? It sure does look like an alloy problem. That is one drawback to range scrap, it is an unknown composition.
If all else fails give me a shout and I will send some of my Lyman 477's and see if'n it makes a difference.
Jay

[Char-Gar]

Just a couple of thoughts to pitch in the thread;

1. If there is lead in the forcing cone, your barrel IS NOT lead free.

2. I have measures scores of Smith and Wesson 38/357 sixgun cylinder throats and have only found one under .357. I doubt seriously if yours are under that as well.

3. You have to clean the throats before you measure them as lead, lube and powder trash accumulations will throw you off.

4. Your are whizzing in the wind, until you know the size of your cylinder throats.

5. My first thought is your alloy is far to hard for the pressure of your load as that is the most common cause of what you have experienced.

6. I have used Bulleye in my 38 Special loads for many years without feeling the need to change.

7. Calipers are worthless for measuring the inside diameter of a round hole.

[JRR]

Take your revolver to a "smith" and have it checked for chamber/barrel alignment. The forcing cone may also need to be squared off and contoured for longer and smoother lead into the rifling.
Jeff

[hunter74]

Thank you all for good advice! A trip to the smith is in order I guess! I have plans for the revolver anyways. Since I use it for competition, I am thinking about a competition barrel, aristocrat tristep sight rib and smoothing up tha DA trigger. He may as well slug and measure chamber, throats and the new barrel. Would you recommend a different taper of the forcing cone for shooting lead.

[hunter74]

I guess it also could be an alloy problem. I don't have another alloy. Aircooled my alloy holds 10-12 BHN so it isn't that hard. It performs perfect in my 9mm with RF, RN and cone designs.

As mentioned before purchased lead SWCs has not leaded but they holds a BHN of 18-22. I find it strange that my alloy is too hard, but could be I guess.... I am cind of new to the casting game but I have used stone hard cast boolits for 15 years in my gun without problems.

[duck hollow pete]

you are missing Larry's point per alloy, sb does not alloy with pb, add sn to equal sb for a true alloy. this will give you a true bhn reading. try it as is or soften to spread the tin cost out. then worry about the other factors.

[hunter74]

Ahh..... Forgive me for beeing slow :-)

I have tried it without added tin but they suffer from poor fillout and do not look as pretty as with a little tin added :-)

[bigboredad]

I had the same problem with my range lead when It cooled. Water dropping cured it for me YMMV

[hunter74]

Tried a bit different alloy mix in yesterdays casting session. I added about 4 % pewter into the alloy and the boolits came out perfect from the mold. No wrinkles, dents or flaws in any way. It sure helps to add a bit more tin than I'm used too. Looks promising. Oh...and I water dropped them...

Loaded up some loads in 357 brass to try that out for tomorrows shooting session, with my new cast boolits.

I took some new measurements of the newly cast boolits and I noticed one thing I have to ask about. When I measure the diameter of the boolit base and the front driving band above the crimp groove, they are not the same. From what I can read from my analog micrometer, the boolits diameter around the base is 0.0004"" (just under half a thousand"") smaller than up on the front driving band! Is' this bad? Can this have anything to do with the leading? I use a Lyman 450 and with the nose punch provided with the mold, I can't get the boolit deeper into the sizer so it's not easy to get the front driving band to get more down sized.

Thanks again! I hope you don't get bored with my search for wisdom :)

[Mal Paso]

I use a Lyman 450 and with the nose punch provided with the mold, I can't get the boolit deeper into the sizer so it's not easy to get the front driving band to get more down sized.


There is a depth adjuster under the die.

[hunter74]

Yesterday’s range session revealed the same results as before. Leading in cylinder mouths with SWCs regardless of alloy, powder type, powder charge or brass, Magnum or Special.

Tried the Mihec 140 gr 9mm boolit sized to .357 and the leading was almost non-existent and the accuracy very good. Guess I’ll use this boolit in the future until a smith has revealed the cause of the problem. I suspect a rough cylinder mouth. I guess it could be more forgiving with a tapered boolit than the sharp edge of a SWC….

[Char-Gar]

I have followed this post with all of the suggestions. I don't know what your problem is, but there is no reason your Smith will not shoot .358 SWC bullets without this problem if there are no other issues, which you most certainly have.

Here is my list of possible culprits;

Load Related

1. Bullet to hard
2. Bullet to small
3. Lube is worthless

Gun Related

1. A very rough forcing cone, that acts like a file when the bullet passed over it. This is common in Smith and Wesson pistols. A forcing cone recut with an 11% taper will cure this problem.

Bottom Line...Folks have talked about all the load related issues, so my money is on the gun as the root of the problem.

I have fired many, many thousands of round through various Smith and Wesson 38 Special and 357 Magnums with both cases and never had a problem that could not be fixed with attention to the forcing cone.

I have never used range scrap and the powders in question, so I can't speak to those choices. I use ACWW, Bulleye, Unique or 2400 and my own home made lube. Bullets are sized .358.

[outdoorfan]

Come to think of it, when I shot the 358477 in my 686, that boolit leaded the cylinder throats as well. However, the forcing cone and barrel remained clean. I don't know if the problem is your throats that are leading to the point that it's carrying over to the forcing cone or if the forcing cone is also too rough, but I think Char-gar's suggestion to 11 degree the cone is probably a good one.

If you fire one shot in each hole in your cylinder, then look at the cone, is the cone leaded?

Another thing that I think would benefit you is to open up those cylinder throats by at least .001. I did that to mine, and now my gun shoots even better. I also think the by doing it with emery cloth and going back and forth with it (dowel) also might smooth things up a bit more?

I did mine by hand with a split dowel and some every cloth. Worked great.

[hunter74]

The cylinder throats leads but the forcing cone is lead free if I only shoots a few shots. If I do many shots the leading creeps into the forcing cone. It looks like the throats are rough but not the cone.

I have tried with a lot of different lubes, hard and soft and it does not seem to matter with the 477

[hunter74]

It does not seem to matter if I shoot 357 or 358

[outdoorfan]

The cylinder throats leads but the forcing cone is lead free if I only shoots a few shots. If I do many shots the leading creeps into the forcing cone. It looks like the throats are rough but not the cone.

I have tried with a lot of different lubes, hard and soft and it does not seem to matter with the 477

Okay, so if I were you I would do what I did to my 686. The throats could stand to be opened up some, no to mention the smoothing action some emery cloth on a split dowel (on a drill) moved back and forth through the throats will do. PM me if you want to go this route and have some questions. I learned some things in the process. It's easy enough to do. Takes a couple of hours (at the most, usually). If you're careful, it should turn out great!

[Char-Gar]

Before you do anything else, clean all lead out of those cylinder throats. I mean every speck, down to the bare metal. This can be quite a chore. Look into the throats from the front with a very strong light. If you can see silver looking reflective places, that is lead. You can't tell squat just looking from the rear of the cylinder at a light source.

I am against putting stainless steel brushes in a barrel, but will use them in cylinder throats. 000 Steel wool is better but slower.

A throat with lead in it, will just attract and hold more lead from the bullets that pass through it.

[HDS]

I have a revolver with a sharp step in it before the leade into the throat starts, it seems it's not uncommon and there seems to be debate as to whether it's even a flaw or not. Anyhoo when I shot full wadcutters sized to .431" they would shave of pieces of lead that would remain in the throats, if I keep shooting this leading will also be forced into the forcing cone.

Sizing the bullets down to .430" (same as throats) cured that problem for me. It doesn't seem to happen with .431" sized SWCs, or at least it's quite minute in comparison, sizing them down to .430" would probably be for the best but I want to use the same rounds in my '92 rossi and it definitely wants .431".

[ku4hx]

emery cloth on a split dowel (on a drill) moved back and forth through the throats will do.

Yep, a little piece of, oh, 600 grit emery cloth in a variable speed drill can work wonders. Works beautifully on steel resizing dies too.

[hunter74]

I took your advice to give the chambers a thorough scrubbing. I used my drill and VFG plugs in 375 caliber. I used Gold Medallion on the plugs. It’s a bore cleaner paste almost like JB paste. After a few minutes with the drill all the chambers where like a mirror inside. I don’t think they have been this clean since the revolver was new about 15 years ago. What I noticed was that the cone in the chambers looked to be pretty steep. No wonder this could shave lead !

I’ve heard different opinions about the optimal forcing cone taper. 11 degrees some say and others say that it’s ok with original taper which I'll guess is much steeper. Is it this step before the throats they mean? The forcing cone is the taper in the beginning of the barrel right?

[outdoorfan]

Yes, the forcing cone is the beginning of the taper in the barrel. The "throats" can only refer to cylinder throats in the cylinder, as far as I know. Are you mixing terms here that shouldn't be mixed?

Sounds like your forcing cone is okay. You mentioned that you can visibly see quite a step in the cylinder throats. I remember that mine were like that also. I had build-up when shooting the 358477, just not enough to transfer and lead the barrel.

[hunter74]

Ok, then I got the terms right, just want to be sure. It sounds like there are two fixes to the problem. 1. Use other boolits than WC/SWCs to make the transfer of the boolit into the throats, a more gentle one.
2. Have my smith to make the taper more smooth and less steep

[hunter74]

Took two pics of the throats. It may be difficult to see on the pics but here they are.

[Tom Myers]

Hunter47,

In order for you to acquire a visual image of your chamber and cartridge fit, attached is a series of image sketches of the my S&W Model 66 chamber configuration showing the position and fit of the bullets and cartridges you are currently working with(Click on the images to view full size).

I do not have any data on the chamber specs for the S&W Model 686 but you can probably devise some method of obtaining a chamber cast or impression that will allow you to determine the interior radial and angular dimensions of the leade and throat portion of your chamber. One method that I have used with success is to remove the cylinder and place the cylinder face on a hardwood block, drop a soft cast bullet into a chamber then, using hammer and a brass rod or short wooden dowel, while holding the cylinder face tight to the hardwood block, impact the bullet until it fills the throat and lead area flush to the face of the cylinder. Then simply tap the impression out towars the rear of the cylinder to measure the interior dimensions of the throat leade area.
If the bullet is large enough to completely fill the leade and throat area, you have all the dimensions needed to determine the length of the throat and the length and angle of the leade to the throat and also the depth of the chamber to the start of the leade.

The angle of the leade can be calculated by subtracting the throat diameter from the chamber neck diameter then divide that amount by 2. divide the result by the length of the leade and then either use a calculator to find the Arc Tan function of the product or (for small angles such as this) simply multiply the results of the division by 57 (57 is a round-off of 180 deg. divided by Pi [3.1416]) to find a close approximation of the angle.

Using the dimensions from the 686 cylinder sketches below.
0.3830 (Neck2 dia.) - 0.3578 (Throat Dia.) = 0.252 / 2 = 0.1260
0.1260 / 0.1106 (leade length) = 0.113924
tan-¹ or Arc Tan(0.113924) = 6.4993 or 6 degrees and 30 minutes.
OR
0.113924 x 57 = 6.49466 degrees.

The max length of the cartridge case cut can of course be determined by subtracting the throat length and leade length from the cylinder length.

Hope this helps.


72977

72981

72983

72979

[outdoorfan]

Ok, then I got the terms right, just want to be sure. It sounds like there are two fixes to the problem. 1. Use other boolits than WC/SWCs to make the transfer of the boolit into the throats, a more gentle one.
2. Have my smith to make the taper more smooth and less steep

I'm not sure that simply reaming the throats (what I think most smiths would do) will necessarily fix your problem. Yes, it will open up your throats more, and that might help. However, the apparent sharp leade into the throats is where I think your problem is. I don't think a reamer will remedy that (someone correct me if I'm wrong). Using the dowel and emery cloth method should smooth that up a bit WHILE your throats are being opened up to a more suitable size for shooting cast.

[HDS]

Ok, then I got the terms right, just want to be sure. It sounds like there are two fixes to the problem. 1. Use other boolits than WC/SWCs to make the transfer of the boolit into the throats, a more gentle one.
2. Have my smith to make the taper more smooth and less steep

You could try an SWC sized to just below the throat size, like .005" below it. It would be good if the driving band of the bullet just about touched the leade into the throat to support it as well. Thats how I got my 629 to work with full wadcutters and a definite sharp step in the leade (I believe this is the proper name for the taper in the cylinders).

[hunter74]

I suspect the alloy in combination with a steep leade is the problem. The same gun has shot well with harcast lead in the past, also SWCs with hard lube. I have tested a little more and the alloy with 4% tin added, leaded the cylinder mouths as bad as before with less tin. The problem was also bade with the Mihec boolit, so I guess my earlier comments about them was wishful thinking.

I've read a little about Elmer Keith and his experiments back in the day...... As I understand he used pure lead and added about 6% tin. Is there a point for me to try to add 2 more %s of tin (pewter) so I get up to 6, or is this a waste of time? Maybe then my alloy would get gloser to Elmer's :) It worked for him, and I use his boolit design :)

[outdoorfan]

I think you're wasting your time trying some super duper wonder alloy to make this work. I would either try a different boolit that is proven to work in your gun or go ahead and open up those throats, polishing the leade as you go. That should take care of it.

[Mal Paso]

Does this throat leading happen with Mag Brass?

[hunter74]

Yep, the same with magnum brass.

[Mal Paso]

Only other thing I can suggest. Another forum member had throat leading in a 625 which he cured by sizing boolits .002" over the throat diameter. It is an outstanding shooter now, don't know about before.

[outdoorfan]

Only other thing I can suggest. Another forum member had throat leading in a 625 which he cured by sizing boolits .002" over the throat diameter. It is an outstanding shooter now, don't know about before.

I doubt this is the case here. A fatter boolit means more lead to size back down as they pass through those skinny little throats, not to mention the rough transition through those leades. :grin:

[Mal Paso]

If lead was being shaved it should be loose chips that follow the bullet out of the chamber. What if an oversize chamber allowed enough gas past the bullet to remove a small amount of lead which gets deposited on the next available surface. Gas Cutting is a real phenomenon. A huge amount of effort goes into fitting rifle cartridge necks but no one measures revolver chambers.

Flame away. Pun Intended!

[hunter74]

Visited the local scrap yard today and they had some roof lead and lead from “lead glass windows”, the kind popular in churches. It seemed really soft and the man proclaimed it was pure lead. I filled half my pot with this lead and the rest with my range lead, and added 2 % tin. I water quenched the ‘477s. My BHN reader stated 12 BHN. I’m sizing this to 358.

I’m quite exited for tomorrows range session.

[hunter74]

Just another update….

Today’s test looked promising indeed! I shot about 25 boolits through my revolver loaded with Vhita Vouries Cowboy Action Powder – Tin Star 32C in .38 brass . And the leading was almost non-existent. A small amount of lead/carbon was deposited in the leades but this all came out with one patch of oil through the cylinders. The bore and forcing cone looked lead free.

I guess the trick was to thin out the range lead with some pure lead. I have to shoot some more to be sure but now I’m optimistic!

In the 9mm pure range lead works, so I guess I’ll keep two types of alloys in the future. If it ain’t broke, don’t fix it, right ?

[outdoorfan]

If that works then Larry Gibson's suggestions were spot on. Glad to see you're getting it resolved (hopefully).

[detox]

Loose lead shavings in crimp groove will cause leading. Be careful not to shave lead when seating boolit. Seat boolit using two step method to prevent. Also bell case mouth just enough to prevent.

IMO too much thought is going into this subject. Try a well loaded proven load (20/1, SPG lube)...problem solved....for subsonic rounds atleast.