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Discussion Starter #1
I didn't shoot any better than I usually do, but I made some significant progress.

I've been having a nasty leading problem with my model 66. The worst part was the face of the cylinder would just become coated with lead. This revolver has been re-done and the gap is .004 so it wasn't that. Chamber / barrel alignment looked fine. Some more research lead me to think I needed .357 diameter rather than .358. The throats measure out to .3575. I bought a Lee sizer in .357 and just ran my (purchased) cast 158 gr SWC through it and re-lubed with liquid Alox. Presto-bingo! 150 rounds fired and zero leading anywhere. Instead of taking me an hour to clean it took about 15 minutes, and to be honest I'm not even sure it even needed cleaning.

Accuracy wasn't outstanding, but it wasn't any worse than before. Now I need to go back and work through a bunch of test loads to see if I can get it to group a bit tighter. The load was a light .38 spl: 3.5 gr Universal and a 158 gr cast SWC. The 4" circle targets are 25 rounds standing, the square ones are shooting for group off sand bags. Both at 15 yards.

I've been dealing with the above issue so much that I had put off starting up reloading for 9mm. I finally got around to it and was pretty happy with my first test rounds shot off a bench at 15 yards. The 125 gr RN with Bullseye shot the attached target. I was happy with it considering the PT609 is a compact, and an inexpensive gun. I wasn't expecting match grade results. The good news is it seemed to shoot to the point of aim more or less with the straight eight sights.
 

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You do need to size your bullets to the throats, but if your throats are undersized, the gun will lead badly.The only cure is to ream the throats to .001 to .0015 over groove diameter. In this case it should be .357, but you have to slug the barrel to be sure. The gap has little to nothing to do with leading.
 

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Discussion Starter #3
You do need to size your bullets to the throats, but if your throats are undersized, the gun will lead badly.The only cure is to ream the throats to .001 to .0015 over groove diameter. In this case it should be .357, but you have to slug the barrel to be sure. The gap has little to nothing to do with leading.
Can't slug the barrel, it's a S&W 5-groove so who knows................I'm going to try some other loads and either leave it alone or ream the throats out.
 

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All I know is....I wish I could shoot like that.....way to go!!!
 

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I'm not really a handgun technician / expert, like some of you are; and I learn something new about handguns, munitions, safety, and firearm maintenance every time I read a well-written, technical post on this forum...and the incisive and informative comments that it evokes.

Thanks for the "college education" you folks are giving me every time I log on to TaurusArmed.net! :icon_ peace:
 

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Discussion Starter #7 (Edited)
Will a .357 jacketed bullet pass through the throats easily?
Yes. A .358 lead bullet won't, I have a pin gauge set and the .3575 just fits perfectly. You have to get it aligned perfectly but once you get it in it moves freely. From what I read, .3575 is the factory spec. but I've never had this problem before with other S&W's. I don't have them anymore, but they were mostly a bit older than this one. I don't know if they changed their specs at some point to accommodate the fact that jacketed bullets are now the standard, or if I just got one with wider throats on the other one I used to have.
 

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Most revolvers are set up to shoot jacketed these days. The pin set is the best way to check ID, so we know that is accurate.

There are other reasons for leading. The lead all over the cylinder face concerns me. It tells me the hot gases are leaking past the bullet and cutting the lead bullet as it passes through the throats. It makes me wonder if the bullets are undersized. Are you using a FCD? Does it make a lot of contact with the round when crimping? lead is dead soft compared to brass and will not spring back like brass does, loosening neck tension depending on the carbide ring diameter and the bullet diameter. The hardness can be a problem. It needs to match the pressure. What pressure/velocity did you shoot them at, and what BHN are they?


Some basics on leading:

Undersized bullets, unless they have enough pressure to bump up and fill the bore, will cause gas cutting and leading when the hot, high velocity gases "cut" lead off the bullet on its way between the bullet and the throat and/or barrel. Leading will be mostly at the throats and forcing cone, but will continue until it fills the whole barrel if you keep shooting the offending load.

Properly sized bullets (in the range of .001 to .002 over throat diameter) will not suffer from gas cutting unless they are too hard.

Bullets that are too hard will not bump up and seal the throats and barrel well, even when sized properly, causing leading.

Bullets that are too soft to hold the rifling at the velocity they are driven at, will break loose from the rifling and "skid", breaking the seal and causing leading galore all the way down the bore.

If the bullets are sized properly, you can get away with them being a little harder than needed.

If the bullets are soft enough to bump up easily with the pressure used, you can often get away with them being a hair undersized, as long as they are hard enough to hold the rifling for the trip down the bore.


Oh yea. Bullets that do not have enough, or good enough, lube, will tend to lead towards the end of the barrel.
 

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Discussion Starter #9

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Discussion Starter #10 (Edited)
Most revolvers are set up to shoot jacketed these days. The pin set is the best way to check ID, so we know that is accurate.

There are other reasons for leading. The lead all over the cylinder face concerns me. It tells me the hot gases are leaking past the bullet and cutting the lead bullet as it passes through the throats. It makes me wonder if the bullets are undersized. Are you using a FCD? Does it make a lot of contact with the round when crimping? lead is dead soft compared to brass and will not spring back like brass does, loosening neck tension depending on the carbide ring diameter and the bullet diameter. The hardness can be a problem. It needs to match the pressure. What pressure/velocity did you shoot them at, and what BHN are they?


Some basics on leading:

Undersized bullets, unless they have enough pressure to bump up and fill the bore, will cause gas cutting and leading when the hot, high velocity gases "cut" lead off the bullet on its way between the bullet and the throat and/or barrel. Leading will be mostly at the throats and forcing cone, but will continue until it fills the whole barrel if you keep shooting the offending load.

Properly sized bullets (in the range of .001 to .002 over throat diameter) will not suffer from gas cutting unless they are too hard.

Bullets that are too hard will not bump up and seal the throats and barrel well, even when sized properly, causing leading.

Bullets that are too soft to hold the rifling at the velocity they are driven at, will break loose from the rifling and "skid", breaking the seal and causing leading galore all the way down the bore.

If the bullets are sized properly, you can get away with them being a little harder than needed.

If the bullets are soft enough to bump up easily with the pressure used, you can often get away with them being a hair undersized, as long as they are hard enough to hold the rifling for the trip down the bore.


Oh yea. Bullets that do not have enough, or good enough, lube, will tend to lead towards the end of the barrel.
Yeah I've never seen a revolver lead the cylinder face like this one did. It was bad. It even built up a ridge of lead on the outside surface of the cylinder at the forward edge. When the gap was reduced this decreased significantly, but it was still there. Barrel leading doesn't concern me much as long as it doesn't affect accuracy. A little barrel leading isn't difficult to remove. Since leading of the cylinder face disappeared when I went to a .357 bullet, I presume the slightly narrow throat was shaving (rather than swaging) the cast bullet and blowing it out the gap.

I don't use the Factory Crimp die on lead bullets. Most of the time just a roll crimp. Sometimes on full wadcutters I use a Redding Profile Crimp die.
 

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I like your practice makes perfect attitude, Glen. Also your persistence in working out your hand loads is admirable as well. I don't know if I have the time or even the patience anymore to work on loads until their performance is where I want them to be.
 

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Discussion Starter #12
I like your practice makes perfect attitude, Glen. Also your persistence in working out your hand loads is admirable as well. I don't know if I have the time or even the patience anymore to work on loads until their performance is where I want them to be.
Well the downside is that I will probably never get to where I want to be.....
 
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