.357 mag leading issue ....any thoughts?

[JWFilips]

Hi All,
I'm having a leading issue and would like to ask you all a question. I'm shooting 158 grain TC .357 mag bullet sized .378" BN 18 (Penn Bullet) sized .358"
I have a K framed S&W model 19-3 from 1979 ( 6 " barrel) I get very little to no leading in this pistol with my loads using this bullet however I also have a N framed S&W Model 27 from 1953 (6 1/2" barrel) with these same loads I get a lot of leading in the cylinder throat, forcing cone & 1/3 down the barrel (I am seeing some light leading the full length of the barrel also) I feel the guns are pretty similar Actually the Model 27 even though it is older has not had many shots fired through it even though it is 60 years old The Model 19 has probably had more or maybe the same amount of rounds thru it. Is there any reason to explain this and more importantly how can I stop the heavy leading in the Model 27.
Thanks
Jim

[cbrick]

You lost me with .378" sizing.

Have you slugged the throats of either revolver? The groove diameter HAS to be the same or a tick smaller than throat diameter. If the groove diameter is larger than the throats the throats will act as sizing dies and the boolit will be too small for the larger than throats groove diameter.

If the front driving band when the round is chambered is short of the throat it can strike the edge of the throat and shave lead, it will lead the cylinder, then the forcing cone and with continued shooting continue on down the bore.

It sounds like one revolver has proper throat/groove dimensions and one does not but you need to measure them both to know for sure.

Rick

[JWFilips]

Very Sorry.......... Old Age......... I meant .358" sizing

You mention measure the throat Do you mean via slugging?

[runfiverun]

start with the cylinder throats.
then the barell.
if you have a straight [no tight spots under the frame] 357-8 barell and the throats on the cylinders are smaller then theres your problem.
if the cylinder throats are 358 and the bbl is measuring quite a bit under under that you need to determine if it's a tight spot or if the bbl is really that small.

[uscra112]

When the throat and groove diameters checked out AOK on my N-frame, which was a bad leader-upper with cast, I resorted to firelapping. That did the trick.

[Iron Mike Golf]

Very Sorry.......... Old Age......... I meant .358" sizing

You mention measure the throat Do you mean via slugging?

You can slug with pure lead and measure with a micrometer. If you have pin gauges, you can do that.

[cbrick]

You mention measure the throat Do you mean via slugging?

Yes, that or pin gauges if you have them available to you. If you slug the throats be sure to use a slug large enough to completely fill the throats and give you an accurate measurement. Also, use a micrometer not calipers.

Once you have accurate throat diameters then slug the bore for groove diameter. The only reason to slug the bore of a revolver is to know that it is at or smaller than throat diameter and to know that there are no tights spots. Since your leading begins in the throats, spreads to the forcing cone and then down the barrel odds are the throats are too small for the groove diameter.

If you are not set up to do this or are unsure of getting accurate measurements a gunsmith can easily do it for you, shouldn't be very expensive.

You didn't say what your load is but since you get no leading in one revolver and you do in the other it is almost assuredly a mis-match between throats and bore in the revolver that does lead. If the bore is in fact larger than throat diameter the fix is to have the throats reamed to a diameter of at least groove diameter and then size the boolits to fit the throats of that revolver.

If you have the throats reamed and have your own smith be sure this is something he has done before AND he has the PROPER reamer to do the job RIGHT. I have seen smiths do some strange things with the throats. It's a simple job but does need to be done correctly. I recommend the CylinderSmith, you'll only need to send him the cylinder, not the whole gun. He's economical with quick turn around and has an excellent reputation.

Rick

[fredj338]

As often said, fit is king. What works in one rev may be a disaster in another, even of the same make & model. Sounds like a poor bullet fit. As noted, check the cyl throats & slug the bore. Larger bullets are almost always better, almost.

[WyrTwister]

You can not measure the cylinder throats with the inside measuring " jaws " of a dial caliper ?

God bless
Wyr

[243winxb]

BN 18 needs a near maximun loading. Try 13.0gr of 2400 in the 357 mag case.

[JWFilips]

OK Guys, I really appreciate your replies: Tonight I slugged the barrel & throat (Pure lead balls) These are the numbers I came up with.....I picked the chamber throat Slugged it I measured it at .357" using two different micrometers and a dial caliper Then I did the bore The "maximum" diameter on that slug ( I would think these would be the grooves) measures .355" Same measuring devices. I'm not sure I know what a "pin gauge" is?
Does this sound correct? So If I did this correctly what does it all mean?
BTW I picked up some 2400 powder today to punch up my loads

Someone asked about my loads Well here are just a few I have shot out of both pistols
My favorite light target load of 4.7 grain Bullseye and a hard cast 125 gr TC cast Crono'd at 930 FPS
also a 6.0 grain Bullseye loading with a hard cast 158 TC (Penn bullet)
But I don't think anything as fast as what was mentioned of 13 gr 2400 I would think this would be for a 158 grain bullet correct (?)

[40Super]

Have you tried a softer bullet,say 12-14bhn? I believe Penn has then or Missouri will.

[JWFilips]

Have you tried a softer bullet,say 12-14bhn? I believe Penn has then or Missouri will.
Well I'm just shooting what I had for my S&W 19 so No I have not. I figured if they shot well in my 19 they should be fine in my 27 ( starting to think, not!)

[454PB]

S&W barrels are hard to measure, due to the odd number of grooves. I do it by slowly turning the boolit while it's in the micrometer and getting an "average". You can also wrap the boolit with thin shim material, measure, then subtract twice the shim thickness.

I'd be surprised if you barrel was .355", I've owned quite a few S&W .38 specials and .357 magnums and I've never seen one that small.

A pin gauge is simply a precision machined steel pin that is placed within the chamber throat and used like a feeler gauge.

assuming your cylinder throats are .357", the .358" boolits you are using are being sized down before they hit the barrel. You may as well use .357" boolits.

[JWFilips]

S&W barrels are hard to measure, due to the odd number of grooves. I do it by slowly turning the boolit while it's in the micrometer and getting an "average".

Yes this is what had to do. But actually the .355 was the largest measurement I got! I will try this test again tonight to see if I messed up somewhere & post results Thanks

[243winxb]

But I don't think anything as fast as what was mentioned of 13 gr 2400 I would think this would be for a 158 grain bullet correct (?) Yes, 158 gr cast lswc.

[JWFilips]

Ok, Tried again tonight I pushed a pure lead .440" ball into the chamber throat and the barrel. After many measurements the largest number I can get out of the throat is .357" and the largest measurement I can get by rotating the bore slug in the mic as well as caliper jaws seems to be .356" I'm not sure if this makes any sense? My machinest friend said he could measure the insides of the throats accurately so I may run it over there tomorrow...but I'll have to wait till the weekend to try the 2400 powder combo ( only time I can get to the range)

[454PB]

Assuming your latest measurements are correct, you have a correct "fit". Next step would be bore roughness, a barrel constriction, or lube failure.

What nags me is leading within the chamber throats, that indicates gas leakage.

[JWFilips]

Assuming your latest measurements are correct, you have a correct "fit". Next step would be bore roughness, a barrel constriction, or lube failure.

What nags me is leading within the chamber throats, that indicates gas leakage.

I do know that my brass seems to be much cleaner on this 27 S&W after firing but my 19 shows some carbon staining. Not sure if this is a hint or indicator of why the 27 is leading in the throat

[JWFilips]

This morning I had time to run over to my machinist friend who used a precision inside cylinder micrometer to measure my chamber throats He got a consistent .359" ( Way different then my slugging?) He said that that was a bit large & also checked 2 of his S&W 357's A 19 & 686 to compare & both were smaller @ .357"
Again I don't know what this means for shooting casts but he as told me the same thing....... Switch to 2400 powder & see what happens

[454PB]

Did you also have him measure the bore?

If you have .359" throats and a .356" bore, the results you're seeing make more sense.

[357shooter]

Do the bullets drop right through the throats? They should take some pressure to get on all the way through. I had a Taurus with 359 throats, it liked unsized pan lubed bullets. I don't recall what the bullet diameter was exactly. It needed every bit of it to keep from leading the throats. It was accurate, but those large throats liked large bullets.

[JWFilips]

Do the bullets drop right through the throats? They should take some pressure to get on all the way through. I had a Taurus with 359 throats, it liked unsized pan lubed bullets. I don't recall what the bullet diameter was exactly. It needed every bit of it to keep from leading the throats. It was accurate, but those large throats liked large bullets.

Yes my 158 TC Penn's slide right through! Gee was that simple ! I can't believe I didn't think of that before They do not go into the throats of my 19 so there is the difference. Now I guess this means I'm going to be needing .360 Bullet sizing for this gun?
Correct ?

[JWFilips]

Did you also have him measure the bore?

If you have .359" throats and a .356" bore, the results you're seeing make more sense.

Yes It looks like the final numbers which are the most accurate ate .359" throats and .356" groove dia.
So Is there any fixing this leading problem ? Chamber throat leading is still the puzzle here since my .358" sized cast 158 gr boolits slide thru the chamber throats so easily?

[WyrTwister]

Yes It looks like the final numbers which are the most accurate ate .359" throats and .356" groove dia.
So Is there any fixing this leading problem ? Chamber throat leading is still the puzzle here since my .358" sized cast 158 gr boolits slide thru the chamber throats so easily?


Bigger bullets or pay S&W or some one to put a new cylinder in the gun ?

I think 9 x 18 mm bullets are maybe .360 " ? Do not know for sure , I do not load for the Mak ?

God bless
Wyr

[454PB]

If it was my gun, I'd cut my losses and use a gas checked boolit.

[357shooter]

Yes my 158 TC Penn's slide right through! Gee was that simple ! I can't believe I didn't think of that before They do not go into the throats of my 19 so there is the difference. Now I guess this means I'm going to be needing .360 Bullet sizing for this gun?
Correct ?
You can try some swaged bullets, at 1,000 FPS or less. They may work and are inexpensive. If any of the casting companies sell a .360 with softer alloy, that should work. If you want to get into casting, a mould from NOE or one of the excellent companies here will drop at .360 too. Moulds from the big companies will drop smaller and most likely won't meet your needs.

I shoot .360 in all my 357 revolvers/rifles, using range lead 95% of the time. I don't shoot 180 grain bullets at max pressure either, which some of the guys here do. So for target and plinking velocities, the soft fat bullets work for me. In the rifle I do use a gas check at 1,850 FPS, still with the range lead, with no leading and excellent accuracy.

[JWFilips]

Thanks Guys for sticking with me on this long thread and helping me out. I never used gas-checked boolits. I guess gas checks can't be applied to my existing boolits I have here in stock correct? I guess this is the push to start casting myself.
I will start looking in to a larger mold & sizer since I'm sure I'm going to keep it. Found out it is a pre-27 S&W model from 1953 & I have been told it was a wise purchase by those who have seen it

[WyrTwister]

Thanks Guys for sticking with me on this long thread and helping me out. I never used gas-checked boolits. I guess gas checks can't be applied to my existing boolits I have here in stock correct? I guess this is the push to start casting myself.
I will start looking in to a larger mold & sizer since I'm sure I'm going to keep it. Found out it is a pre-27 S&W model from 1953 & I have been told it was a wise purchase by those who have seen it

Here is the Lee chart

http://leeprecision.com/bullet-casting/hand-gun-bullet-molds/bullet-mold-6-cavity/

Buy a 100 GC'ed bullets & give them a try . Get at leasr .358" .

God bless
Wyr

[rockrat]

See if you can buy some .359" or .360" plain base boolits first, and try them in your 27, before you pony up for gas check boolits

[JWFilips]

See if you can buy some .359" or .360" plain base boolits first, and try them in your 27, before you pony up for gas check boolits

Well Today I contacted my supplier of both my favorite cast rounds. 125s & 158s & both said the can size .359" to .360" for me. Just have to know what size to go for . A friend loaned me some .359" sized boolits today so I will try those this weekend!

[357shooter]

Go 360, how soft can they cast? BHN 8-10 would be great unless you plan on shooting full magnum loads most of the time. If that's the case, 10-12 is good.

[JWFilips]

New report: I had a chance to get to the range twice this weekend & both times I fired .359" sized bullets over a nice load of 2400 powder These were 18 bn & Leading was very slight and cleaned up easily ( Not like the hours of work previously) This is more like it & Accuracy was very good!

(Again my chamber throats are .359") Assuming that I stick with my 18 bn hard bullets then should I stick with the .359" sizing or would it still improve more with .360" sizing? What is the rule of thumb? size to throat dimensions or .001" larger

[357shooter]

Good question. There are two schools of thought here. I size 357 magnum bullets larger than throat size for the best results. I only shoot BHN 8-11 and never anything as hard as 18. Mainly because the softer bullets also have proven more accurate, for the loads I shoot. 90% of my loads are midrange 357 or lighter. 10% full house magnums. No "big loads" for a Freedom Arms, at 200 yards. That requires a different approach.

The other school says that bigger than throat size doesn't make sense because the bullets get sized down by throats anyway. Therefore there is no benefit to being large to start with.

I suggest you experiment to see what works best for your gun. None of us can prescribe exactly what that is. Some guns may shoot the larger bullet better, some won't. If you can find something softer, even swaged bullets, give them a try too. I don't even shoot BHN 18 in my rifles. Unless you have some specific reason for shooting bullets that hard you might get more accurate results going softer. WW typically have a hardness of 11-12, a lot of 357 shoot those just fine, a lot of 357's shoot the WW mixed with pure which is softer and get excellent results.

[WyrTwister]

New report: I had a chance to get to the range twice this weekend & both times I fired .359" sized bullets over a nice load of 2400 powder These were 18 bn & Leading was very slight and cleaned up easily ( Not like the hours of work previously) This is more like it & Accuracy was very good!

(Again my chamber throats are .359") Assuming that I stick with my 18 bn hard bullets then should I stick with the .359" sizing or would it still improve more with .360" sizing? What is the rule of thumb? size to throat dimensions or .001" larger

What were they lubed with ?

I try for the biggest bullet that I can & still get them to feed , chamber & function .

Glad that your luck is improving . :-)
God bless
Wyr

[mpkunz]

You lost me with .378" sizing.

Have you slugged the throats of either revolver? The groove diameter HAS to be the same or a tick smaller than throat diameter. If the groove diameter is larger than the throats the throats will act as sizing dies and the boolit will be too small for the larger than throats groove diameter.

If the front driving band when the round is chambered is short of the throat it can strike the edge of the throat and shave lead, it will lead the cylinder, then the forcing cone and with continued shooting continue on down the bore.

It sounds like one revolver has proper throat/groove dimensions and one does not but you need to measure them both to know for sure.

Rick

Worldwide Socialism. The Demokrat battle cry is , "Make a straight way for the Ani-Christ."

[cbrick]

Huh?

Rick

[WyrTwister]

Worldwide Socialism. The Demokrat battle cry is , "Make a straight way for the Ani-Christ."


I tend to agree , but it does not have much to do with the current topic .

Besides , you are preaching to the choir .

God bless
Wyr

[JWFilips]

Good question. There are two schools of thought here. I size 357 magnum bullets larger than throat size for the best results. I only shoot BHN 8-11 and never anything as hard as 18. Mainly because the softer bullets also have proven more accurate, for the loads I shoot. 90% of my loads are midrange 357 or lighter. 10% full house magnums. No "big loads" for a Freedom Arms, at 200 yards. That requires a different approach.

The other school says that bigger than throat size doesn't make sense because the bullets get sized down by throats anyway. Therefore there is no benefit to being large to start with.

I suggest you experiment to see what works best for your gun. None of us can prescribe exactly what that is. Some guns may shoot the larger bullet better, some won't. If you can find something softer, even swaged bullets, give them a try too. I don't even shoot BHN 18 in my rifles. Unless you have some specific reason for shooting bullets that hard you might get more accurate results going softer. WW typically have a hardness of 11-12, a lot of 357 shoot those just fine, a lot of 357's shoot the WW mixed with pure which is softer and get excellent results.

357shooter:
So If I hear you correctly, switching to softer lead & properly sized ( what my suppliers call "Cowboy bullets") should let me shoot target & medium loads with my .357 mag revolvers and no worry about leading. Just how fast can you shoot a 11-12 BHN bullet before I have to worry? My suppliers say to limit those to 930 FPS but it seems you guys are going beyond this. I started out buying the 18 BHN lead because I knew I could shoot magnum velocities but yet, when it comes down to it most of my shooting is done with light Bulleye & Unique loads...however if I want to go higher with 2400 powder I would then have to switch hardness? correct?

Also Since my S&W 19 has .358" throats and the pre-27 has .359" throats can I use the larger bullets ( sized .359") in the smaller 19? ...so I only have to buy one size?
I'm sorry for all the questions but there are so many "golden apples" on this site I can't resist picking some! Wish I was more experienced shooting cast bullets so I could share some knowledge with you all but when it comes to PB ...I'm a Nu "B"
Thank You for all of your help
Jim

P.S. Some day I hope to learn how to cast, but my life at this time only permits me to buy some lead cast bullets ...load them and try to get to the range to shoot them. But I sure do wish to learn as much as I can on all the facets of CB's!

[357shooter]

I suspect the velocity limitation the suppliers suggest is more based on the lube they used rather than the hardness of the alloy.

In my 357's WW (BHN 11) will shoot full house rounds all day long without leading. Nothing harder is needed or is helpful. However almost everything I cast is softer than that. BHN 8-10, I shoot full house loads with that in my revolvers with no leading, the lever rifle likes BHN 11ish for high end velocity over 1,500FPS. I size everything .360, which all my moulds produce. For the softer bullets, I usually add 1.5% tin. There is more to the alloy than just hardness. Being a tough alloy matters too, but like I said. You'll need to try them out to see what will work from the suppliers since you cannot control the mix.

The big difference is, I use a good lube like NRA or Darr (homemade) and not the stuff the casters use. They have to be concerned about it staying on the bullets during shipping, in hot trucks, etc...

[JWFilips]

I suspect the velocity limitation the suppliers suggest is more based on the lube they used rather than the hardness of the alloy.

In my 357's WW (BHN 11) will shoot full house rounds all day long without leading. Nothing harder is needed or is helpful. However almost everything I cast is softer than that. BHN 8-10, I shoot full house loads with that in my revolvers with no leading, the lever rifle likes BHN 11ish for high end velocity over 1,500FPS. I size everything .360, which all my moulds produce. For the softer bullets, I usually add 1.5% tin. There is more to the alloy than just hardness. Being a tough alloy matters too, but like I said. You'll need to try them out to see what will work from the suppliers since you cannot control the mix.

The big difference is, I use a good lube like NRA or Darr (homemade) and not the stuff the casters use. They have to be concerned about it staying on the bullets during shipping, in hot trucks, etc...

I think you may be correct on the manufacturer's lubes. I wonder if it would be worth my time to get the casts unlubed and apply my own lube. Again at this time I can not do any casting but if lubing is something that I could do I would give it a go to get more accuracy. Can pre sized bullets be lubed or is that part of the sizing process?

[40Super]

You can lube them at any time, before or after/with sizing.

[swheeler]

Yes It looks like the final numbers which are the most accurate ate .359" throats and .356" groove dia.
So Is there any fixing this leading problem ? Chamber throat leading is still the puzzle here since my .358" sized cast 158 gr boolits slide thru the chamber throats so easily?

That is the problem, size your boolits to a minimum of .359" the size of the throats, .3595 probably better. You are getting leading in the throats because you are getting gas leaking/cutting past the boolits that are .001" smaller than the throats.