.38 Wadcutter Leading

I put about the same number of rounds through my S&W 52 and S&W 686 but there is significantly more leading with the latter.  Why is that?  Does it have to do with differences in barrel twist?  Speer 148g HBWCs were used.  The leading was so severe with the revolver that after about 30 rounds the bullets were keyholing.  Before that I was getting nice clean paper punched holes.

Unless I'm mistaken the twist for all S&W 38/357 is 1-18 whether it's for the 52 or the 686.

If you have pin gauges check the cylinder throats in the 686 and see if they might be undersized compared to the barrel. That would cause barrel leading


Virgil

Take this FWIW.. on a casting forum (not Cast Boolits), Ed Harris, the fellow that is well known for casting, and authored the "Loading Bench" in the NRA mag years ago, was asked why the newer Revolvers were leading, but not the older ones. 

Anyways, he found that the leading problem with the newer S&W revolvers started when they used EDM to machine the cone, he feels that caused the problem, something about being porous when done.

 I had a newer 625 (probably EDM)  that would lead using a RN, but didn't when using a SWC. That's using the same lead to cast, and the same lubrisizing die to size.  Go figure.....

My 686 is a dash 4 without a lock.  Is that considered one of the older ones?  Is there any way of telling the difference between the cones?

I don't have any pin gauges.

My 683-3 will lead much quicker than my 52 also

Where is the leading present? Cylinder throat? Forcing cone? Muzzle?

I'm guessing with keyholing it's muzzle area. Lewis lead remover, then give the Bullets a lil more lube.

Forcing cones have been a problem since the inception...
Never saw one that was centered.. Crude and rough..Taylor Throat is far superior...

james r chapman wrote:Where is the leading present? Cylinder throat? Forcing cone? Muzzle?

I'm guessing with keyholing it's muzzle area. Lewis lead remover, then give the Bullets a lil more lube.

I just saw heavy leading at the beginning of the rifling, about a half inch in length.  There could've been some elsewhere that I didn't notice.  I have a Lewis lead removing kit on order and will give the throat and barrel a good cleaning.  So far all I've been able to do is take the lead out of the barrel.

Jerry Keefer wrote:Forcing cones have been a problem since the inception...
Never saw one that was centered.. Crude and rough..Taylor Throat is far superior...

While doing an online search for "Taylor Throat" I came across the following.  The referenced article from Alpha Precision was especially interesting.  It now seems a wonder that the bullet comes out at all in one piece with most stock revolvers.  My affection for the 686 is beginning to wane.

http://web.archive.org/web/20020606140647/www.sixgunner.com/dad/throat.htm

Is there a way of determining if the bore and cylinder are aligned?  If so, how?

beeser wrote:Is there a way of determining if the bore and cylinder are aligned?  If so, how?

Line boring a swing out cylinder is not practical..
I have done a lot of work on S&W cylinders...One area that the quality control on S&W parts is the cylinder/chamber locations, and they have been on the money... I have  never found a bad one..I have seen many S&W K and L frame revolvers shoot sub inch groups at 50 yards.. So, no need to worry about the potential of these guns.. A forcing cone is archaic.. Why begin to disturb or upset the projectile before it is supported  in some fashion... Think about it... It's one of those, "It's always the way we have done it." things... Jim Stroh knew Taylor.. Taylor was not a gunsmith... Just had the idea.. Jim implemented it.. The process has been around for decades.. Fred Schmidt  used it in his short cylinder guns, to  prevent the barrel extension from cracking...The bullet is trapped and supported prior to any graving forces.. It's a win/win..

Try and push one of your cast bullets thru the cylinder throats, they should not slide easily.

You can tell if the barrel and cylinder are aligned by using a 'range rod.'  They are available from Brownell's.  But, I would try your Lewis Lead Remover first.  Just my opinion.

Since you mentioned "range rod".....

I have the 38 caliber regular and match range rods.  I had a S&W 19 that would accept one of the rods and not the other.  The chambers lined up ok.  The rod stopped at the barrel pin.  Obviously the pin swelled the barrel into the bore just enough to stop the one rod.

james r chapman wrote:Try and push one of your cast bullets thru the cylinder throats, they should not slide easily.

I can't push it through past the headspace unless its really forced.

I asked about this before but does it matter that the .38 Special case falls short of the .357 Magnum headspace.  In other words, I'm using a .38 Special case in a revolver chambered for .357 Magnum.  So it seems that a full wadcutter bullet has to travel a short distance without full contact with the cylinder and then jump across the gap between the cylinder and the forcing cone before making full contact with the barrel's rifling.  Seems like a lot can get messed up along the way.

beeser wrote:

james r chapman wrote:Try and push one of your cast bullets thru the cylinder throats, they should not slide easily.

I can't push it through past the headspace unless its really forced.

You should be able to push it through with a pencil, eraser end first without much effort.  Like I said before, pin gauges are the only good way of measuring the cylinder throats. They should be .357 or better yet .358 and every hole should measure the same. If they are smaller that this  the bullet is being swaged down in the throat and entering the barrel undersized which would cause blow-by and barrel leading. Most all the S&W I have measured have been OK with .358 throats but sometimes things get by (or reamers used to much) and things get undersized. Sometimes throats are different sizes on the same cylinder. Ideally the throats should be .001 over the barrel diameter. To big is bad because while you can open throats to a bigger size you can't make them smaller.

You have to make sure ALL the leading is out of the cylinder throats before you can measure them accurately.


Virgil

I'll get back to this after my Lewis lead removal kit arrives.  It might be a while because they are apparently on back order at Brownell's.

Edit:
Rather than wait for the Lewis kit to arrive I cleaned the bore and cylinders with J-B Bore Cleaner, Hoppe's #9 and a brass brush.  Everything looks shinny.  I tried putting a bullet through the cylinders and it will not go through even trying to push it through fairly hard with a pencil eraser.  Does this indicate a problem?  The bullet was a .358 Speer HBWC.

The bullets must be a tight, slide fit in the cylinder throats. With wadcutters seated in the case, you can use a larger bullet than the cylinder throats.
Next, the bullets need to be at least 0.001" larger than the actual barrel groove diameter.
Next, the forcing cone may need to be polished or re-cut.
Persoanlly, the best L-HBWCs I have found are the Remingtons. Inexpensive and super accurate and the skirt ranges from 0.360-0.361". Some complain they are messy, but I'll take accuracy any day.

Get a choir boy, copper only, wrap strands around your bristle brush, chuck it in your electric drill and run it through your chamber throats.


Lol, I meant Chore Boy! Damn phone...

Go back to 357 cases.
Use the advice here about checking that throats are .0005-.0015 larger than groove by slugging the bore and using pin gauges ($3 each at MSC Industrial - get .357 thru .360 diameters) for the cylinder throats. Fix this if necessary.  Don't size your cases any more than necessary (hint - old school steel sizing dies permit much more adjustment in sizing as they are tapered) or all your work will be lost. 
The above was all probably mentioned here or elsewhere.  What I've not seen mentioned is that I seat my HBWC's out of the case by .125 so that they enter the throats with a slight push. 
With all the above done, if you still have leading (though I don't think you will), you can decide whether you want to fire lap your barrel / have someone polish the forcing cone. 
Or just shoot jacketed stuff
 Good luck.

inthebeech wrote:Go back to 357 cases.
Use the advice here about checking that throats are .0005-.0015 larger than groove by slugging the bore and using pin gauges ($3 each at MSC Industrial - get .357 thru .360 diameters) for the cylinder throats. Fix this if necessary.  Don't size your cases any more than necessary (hint - old school steel sizing dies permit much more adjustment in sizing as they are tapered) or all your work will be lost. 
The above was all probably mentioned here or elsewhere.  What I've not seen mentioned is that I seat my HBWC's out of the case by .125 so that they enter the throats with a slight push. 
With all the above done, if you still have leading (though I don't think you will), you can decide whether you want to fire lap your barrel / have someone polish the forcing cone. 
Or just shoot jacketed stuff
 Good luck.

Thanks!  Should I get the Class X Minus, Class X Plus, Class Zz Minus or Class Zz Plus gages?  All 10 sizes from .357 thru .360?

Class z is .0001 which is fine for this. Even zz would be OK .


+- m
Won't matter, get what's available.

Doesn't really matter outside of a metrology lab, as long as you know what you bought.
Mine are minus.

Another area to check is the part of the barrel in the frame.  You may have "frame choke" (or thread choke)  The frame can constict the barrel a smidge as the barrel is screwed into the frame.  It reduces the bore/groove diameter of the rear part of the barrel.  This is one thing a Taylor choke addresses ("cures?"), as it removes mmaterial from the barrel, opens up the bore diameter/

You then need to look at the progressive reductions of the cylinder throat, the bore diameter (with or without thread /frame choke).  Bullet should be .001-.002" over GROOVE diameter, and groove diameter is hopefully uniform throughout the barrel, or choked so that it gets smaller near the muzzle end.  Cylinder throats should be close to matching the bullet diameter needed to have this condition of being .001 -.002" over groove diameter. (ie if Groove diam is .357", the you may see good gas sealing with a .358-.359" diameter lead bullet, and a cylinder throat that does not reduce that diameter (want to match it).  Then, you don't want any thread choke that will reduce bullet diameter.  Can lead the bore.

Also, make sure all throats are same diameter.  One or two too small will cause the problem also, and open upa group.  There used to be a guy on castboolits.com who reamed cylinder throats for about $35 (cylindersmith.com).  Not sure if he's still doing it.  I had the same problem with my barrel leading with a stainless Ruger GP100 357 mag.  Granted not a bullseye gun (4" barrel). The cylinder throat ran from .355"-.357.  groups at 25 yards ran about 4-5" with lead bullets.  Had some thread choke too.  I had the throats reamed to .358", and firelapped the barrel (60 shots with 320? grit Silicon carbide).  Bore diameter is .357" now, all uniform, and I get nice round 5 shot groups of under 1.5" at 25 yards with a 172 SWC over Unique.  No leading now.

You can measure the degree of thread choke by pushing the slug from the muzzle in an inch or two, then pushing it back out (I used cut off pieces of a hardwood dowel ~ 1.5" long and entered them from the breach end, and was able to push out the slug with a few of them stacked in line), then measure the slug.  This way, you can finger print your barrel for inch-by-inch groove diameter, then compare it to the slug that gets pushed all the way through (the potential thread choked area), to measure the degree of choke to be firelapped or Taylor-throated away to match the rest fo the barrel.

You might be able to detect thread choke by tapping in a soft lead slug into the muzzle and pushing it through the barrel to the breech end.  Lightly oil the barrel first, to aid the push through force.  Note the force needed to push the slugh through the barrel.  You may find more force is needed as the slug gets to the frame area of the barrel.  If this is the case, then you likely have thread/frame choke.  You may be able to fire lap the constriction out with something like 300-400 mesh grit with several cylinder full of soft lead slugs imbedded with the cutting material.  Plently of info on the web to learn to fire lap a barrel.  Use VERY low dosages of powder.  You just need to have the slug come out of the barrel with each shot, you don't have to launch it 100 yards.

The keyholing bullets may be a result of the bullet diameter being constricted by the thread choke, then being smaller than the groove diameter, and not getting good spin on the bullet-even with the skirt of a HBWC.

What powder/charge  are you using with the HBWC?  You don't want too much powder/pressure, as the skirt can deform, and impair accuracy.  Something like 2.25 -2.7 gr of Bullseye is all you need-don't want to blow the skirt with too high pressure.  My S&W m-14 shot  148 grain hbwc better with 2.5 grains of Bullseye, than the "standard" 2.7 grain load of Bullseye.

Also check your HBWC diameter.  I had some commercially swaged "38 cal 148 grain HBWC" that leaded my S&W m 14 badly.  They were .357" diameter.  Too small diameter for good gas sealing at 2.5 or 2.7 grains Bulleye. I had to lube those bullets in Lee Liquid Alox lube to put on addition lube (diameter?), and it helped significantly reduce leading.  I think they were Precision / Delta brand - don't remember.  Remington "38 cal 148 hbwc tend to run larger in diameter (close to .359-.360").  Called "gummy's" due to their stick lube, they tend to shoot very well-but can be messier to load. 

Good luck.

I had a 357 SW19 that had an obvious restriction right at the barrel frame pin.