Any danger here?

[PBSmith]

I'd like to shoot some 190-grain Flat Nose cast pills in my S&W 10-5. This will be slow (under 800 fps) and the bullet alloy is quite soft - scrap lead with a few COWW added - dents by fingernail with little effort...

Ball end diameters of the Smith's cylinder measure 0.3575-0.3580".

The bullets are sized 0.359".

Am I asking for trouble with the bullets being up to 0.0015" over ball end?

[jban]

I am guessing that "Ball end" means your cylinder throats. If that is that is what you mean, then you are good. You want a lead bullet to be a little bigger than the throats and bore diameter. That way it seals goal when you fire it. If you load at cast bullets, they are usually about .002 bigger.

[JimB..]

I’m afraid that @dougguy is gonna yell at me if I get this wrong again, but for a revolver I’m pretty sure that you want the bullet sized to match the throats (bullet maybe .0005 over) and you want both of those to be ~.0015 larger than the barrel groove diameter.

This is for accuracy, I doubt you'll hurt the gun with reasonable loads.

[Dave W.]

Sounds like the ends of the cylinders need to be opened up some.

You need to slug the barrel as well as the cylinders. The boolits need to be .001 to .002 over the barrel diameter. From what you are describing the boolits will probably be undersized before they get to the barrel, because the cylinders will size them down.

I generally run my cylinder throats .0025 over what the barrel diameter is.

There will probably be other more knowledagble people along that can answer better.

[georgerkahn]

I'm definitely not the brightest bulb in the lamp, and can only offer what I have done/do. ;) To wit, after I cast, size, and lub a few cast bullets I insert them -- just the bullet -- in revolver cylinder -- and -- with baited breath -- see what happens. If the bullet drops through with zero friction -- I go no further and either ascertain if I could size a few more a tad bigger (rarely happens to me :() or trash them. Rarely happening, too, are bullets which are too large to be pushed through. Annnnd -- what I hope for -- when a fair-to-middlin' (technical term) amount of pressure allows the bullet to be pushed through (I use a wood dowel) -- I smile and am happy. I then can confidently size and lub the rest, reckoning they'll function well when loaded into cases for this revolver. Although I have micrometers, etc. -- bion I use them not -- just this, as described, manual push-thru check.
geo

[PBSmith]

Am I asking for trouble with the bullets being up to 0.0015" over ball end?

JimB suggests not. Any other opinions on the original question?

[rintinglen]

Probably not, the only difficulty maybe in loading the cylinders if you use speed loaders. The fatter boolit may restrict the cartridge from seating properly without a push from a helping finger or thumb.

The only other thing I could envision is the faint chance of a poorly sized case allowing a boolit to be pushed deeper in the case, thus raising pressure. Proper crimp will prevent this relatively unlikely event from occurring.

You will very likely find that the POA/POI is different from your usual loads. If you plan on killing mice with this load, that may be an issue.

[DougGuy]

You won't hurt the gun with those loads. The harder the alloy, the more pressure it takes to push it through a smaller throat but it would take a LOT to make a load dangerous to shoot. It would have to be already overloaded, and the hard alloy/tight throats would just compound things but they alone wouldn't be the root cause of an over pressure event.

It serves no purpose to size larger than the throats, size to a slip fit with fingers is all that's needed. Providing the throats are just a tad bit larger than the groove.

Many 357 cylinders won't chamber a round loaded with .359" as SAAMI specs (and my own pin gages) designate chamber mouth diameter at .381" and I have reamed quite a few cylinders that wouldn't take a .381" pin all the way to the bottom, so .381" minus .359" = .022" left for 2x case wall thickness. R-P is the thinnest that I know of, WW is the thickest, Starline may be right at .011" I don't have one readily available for measuring.

[reddog81]

As long as the rounds chamber and other standard reloading practices are followed, I wouldn't worry about it.

[super6]

You won't hurt the gun with those loads. The harder the alloy, the more pressure it takes to push it through a smaller throat but it would take a LOT to make a load dangerous to shoot. It would have to be already overloaded, and the hard alloy/tight throats would just compound things but they alone wouldn't be the root cause of an over pressure event.

It serves no purpose to size larger than the throats, size to a slip fit with fingers is all that's needed. Providing the throats are just a tad bit larger than the groove.

Many 357 cylinders won't chamber a round loaded with .359" as SAAMI specs (and my own pin gages) designate chamber mouth diameter at .381" and I have reamed quite a few cylinders that wouldn't take a .381" pin all the way to the bottom, so .381" minus .359" = .022" left for 2x case wall thickness. R-P is the thinnest that I know of, WW is the thickest, Starline may be right at .011" I don't have one readily available for measuring.

Just measured my new starline brass and it in the .010 to .011 range.

[JimB..]

Am I asking for trouble with the bullets being up to 0.0015" over ball end?

JimB suggests not. Any other opinions on the original question?
The internet is female, you ask a question and you get a story that is sometimes relevant.

[atr]

As long as the rounds chamber and other standard reloading practices are followed, I wouldn't worry about it.
I agree....
I also agree that you should check to make sure that the cartridge chambers easily, which is especially a problem if the slug is to great a diameter. For instance I was loading some 200 gr Cast for my .38 special and it took a few dummy rounds before I finally got the size to 0.358 which chambered correctly, easily. Make some dummy rounds to make sure they chamber easily.

[Bazoo]

I think it’s safe. I’d be confident shooting them from a safety standpoint.

[GrizzLeeBear]

Your making it too difficult. Its a S&W .38 special. If your .359 boolits will chamber they will be fine (as long as your load is a safe one). If they won't chamber size them .358.