Sizing 0.001" OVER Cylinder Throat?

5shot

Active Member
I just picked up a lovely Pinned Barrel Model 10-8 S&W. I would be surprised if it had seen a box of ammo through it in the last 40 years. I slugged the bore and cylinder, and all is good there, but the cylinder is right around 0.357. I was planning on shooting as cast, which do chamber just fine, but I have always sized for a slip fit through the cylinder. Will the oversized bullets cause issues in the long term? One post I read mentioned that it would batter the nose of the cylinder. Upon firing the oversized bullet slams into the throat, which would then cause the cylinder to slam into the frame. I would prefer not to size if I don't need to, and I have no desire to have the cylinder modified, since it is already over bore diameter.

Any thoughts on this?
 

waco

Springfield, Oregon
If you size .001” over the cylinder throat, the cylinder throat is just going to size it back down….
Size to a slip fit. Worse case, have the throats reamed.
 

5shot

Active Member
If you size .001” over the cylinder throat, the cylinder throat is just going to size it back down….
Size to a slip fit. Worse case, have the throats reamed.

I'm trying to avoid sizing, and more concerned about any damage that might be caused from long term shooting of these oversized bullets.
 

Rick

Moderator
Staff member
The very best bullet sizer anywhere is the cylinder throats. Doesn't matter how much over throat diameter they are they will be throat diameter exiting. It is possible to lead the throats by shaving the bullet if it's over size and the front band isn't in the throat when the cartridge is chambered. If it were me, I would bite the bullet (pun intended) and size to a mild snug fit in the throats.
 

L Ross

Well-Known Member
I just picked up a lovely Pinned Barrel Model 10-8 S&W. I would be surprised if it had seen a box of ammo through it in the last 40 years. I slugged the bore and cylinder, and all is good there, but the cylinder is right around 0.357. I was planning on shooting as cast, which do chamber just fine, but I have always sized for a slip fit through the cylinder. Will the oversized bullets cause issues in the long term? One post I read mentioned that it would batter the nose of the cylinder. Upon firing the oversized bullet slams into the throat, which would then cause the cylinder to slam into the frame. I would prefer not to size if I don't need to, and I have no desire to have the cylinder modified, since it is already over bore diameter.

Any thoughts on this?
I dunno, I have a few .38 Smiths, (14, 15, 36, 642), and one Model 66 left and they all pin gauge right at .357" and all I shoot in them is .358" bullets. I've never had an issue. The idea of the bullet slamming the cylinder forward sounds like the type of "over thinking" my friends and I engage in all too often.
 

5shot

Active Member
Thanks for all the input guys - I will size a bunch to 0.357 and try it out. Mr. Ross hasn't had an issue, so I guess I will try a few unsized as well and see how that goes. As he said...might just be over thinking.
 

Ian

Notorious member
I have my doubts about the cylinder slamming thing. When the hammer hits the primer, it slams the cartridge and cylinder forward. When the primer goes off it pops the hammer back, backs out until it touches the frame, and drives the cartridge/cylinder forward. As the powder charge ignites and pressure rises, the cartridge brass tries to go out the back of the cylinder and is stopped by the frame, reseating the primer as it goes. Pressure acting on the bullet base pushes the cylinder forward the whole time. None of these actions move the cylinder arbor away from the crane, so there is no slamming due to an oversized bullet hitting the cylinder forcing cone because the parts are already touching.

S&W made no telling how many .38 Specials with .3555-.3565" throats which have digested no telling how many .357" jacketed bullets and I haven't heard of it causing a problem yet unless cast bullets and the resultant smoothbore barrel was a problem.

I'd still size them .357" to reduce lead fouling of the cylinder forcing cones.
 

Jeff H

NW Ohio
Having owned several Charter and Rossi revolvers (among others) over the years, I've found that the place to START is with the "slip-fit" in the chamber throats, but that it's not always exactly best for THAT revolver. I mention Charter and Rossi, because most often, I've found the throats to be on the larger side, so I have HAD to be attentive to this point. There have been at least two Ruger DAs I've owned, where the throats weren't exactly ideal, one 44 Special having large throats and one 357 being small (which I had corrected), but experimentation always seems to be the imperative, because sometimes I end up needing bullets that slip through fairly easily, sometimes I need bullets I have to force through, etc.

MOST often, the standard rules of thumb regarding "fit" FIT, but often enough, I have to break those rules to get the best out of a given revolver. I spent years trying to match up multiple revovlers of the same caliber to all shoot the same diameter of bullet, so I've become more familiar with the topic than I care to be. Been a lot of dinking around and a lot of headaches in the process. I got to where I could make any one of them work, but if I had to size special for that gun, it got corrected or it became someone else's.
 

Matt

Active Member
My experience is that L Ross is correct about Smith and Wesson revolvers. All I’ve ever used my pin guages on (mine are “minus” specification) are a tight .357” this is true for pre-war .38 Spl M&Ps and one registered.357 Magnum. I have a wide range of S&W .38s and .357s and I generally size everything to .358.

There is a problem with bullets slamming into forcing cones; it involves jacketed .357 bullets loaded at maximum velocity splitting the forcing cone of M13, M19, and M66 K frame S&W revolvers. It takes somewhere from 6,000 to 10,000 rounds from my experience. At that point the gas cutting has reached is maximum (thankfully) and things are generally pretty loose. My favorite K frame is a M19-66. At the time I could only find a M66 barrel to replace my M19
split forcing cone. Bill Jordan never expected K frames to shoot a lot of Magnum ammunition

So think about it. Your mold drops at .359”. You put it in a tapered die to reduce its diameter to .357 or 358”. The pressure needed is low. I don’t think a million cycles of this would appreciably wear the die. Transfer this resizing force to the tapered cylinder throats and tapered forcing cone of your barrel. It won’t take a million rounds because of the pressure, heat, and wear from firing actual cartridges. K frames still get loose faster than N frames but I’ve never split a forcing cone from a steady diet of maximum lead bullet .357 loads in K frames.

Size so your cartridges chamber freely first, then let accuracy be your guide. It might be at .357, .358, or even .359. If you are still concerned about damage, size to .357. No one will judge
 

Jeff H

NW Ohio
I have my doubts about the cylinder slamming thing....

I don't know, so I'm not weighing in on that or challenging it, but just as a note of interest, I'll only add to that that with all the Charter revolvers I've owned, the pawl pushes the cylinder forward and holds it there before the firing pin has a chance to drive the cartridge or cylinder forward. It is also why their (if in proper working order) cylinders always seem to lock up solidly* as the trigger moves rearward - when it matters.

*This is not to say that the chambers are necessarily perfectly aligned with the bore, and assumes that the revolver is in good working order.

Not infrequently, a shim at the front of the cylinder is necessary to keep the cylinder face from rubbing on the breech of the barrel. I do believe that they set the B/C gap and "square off" the breech with a file. Not cirticizing or complaining, just sharing an observation, periodic or specific incidents of execution aside, I am a fan of the Charter revolver design.
 
Last edited:

Matt

Active Member
End shake (cylinder moving forward and back on the crane) is traditionaly reduced by stretching the crane by the use a closely fitting liner or spud and the careful peening with a crosspein hammer. Once it’s lengthened a bit too much careful filing to square the end of the crane and setting the cylinder gap. This also effects the headspace to a degree. Crane washers are another way to regulate endshake, but the thickness available can limit fine tuning.

If end shake is not the issue and the cylinder gap is too small then careful filing of the end of the barrel is the solution. I’ve only had to file to set cylinder gap when fitting new barrels and once on a pair of Uberti SAA Colt replicas for a friend that was using them to shoot BP blanks for Cowboy Mounted Shooting. The cylinders would start to bind after about 12 shots. The gap was wonderfully tight and worked great for smokeless cartridges. The crimped .45 Colt blanks were extremely dirty and fouled much more than conventional black powder cartridges.
I think the black powder fouling was much worse in the blank because there was no powder compression.

To me if the cylinder gap is too large is the worst problem. After setting end shake (and very rarely headspace) then there are two solutions; live with it or screw the barrel in a turn. This can be done with a good barret file but is touchy and needs patience to get the barrel to properly “turn” up so the front sight is straight with the barrel torque correct.
 

L Ross

Well-Known Member
I had no end of problems with replica revolvers fouling out with full power black powder cartridges using good lube too. I found a gorgeous Remington 1875 replica in .44 w.c.f. that I could not get through a cylinder full of 5 without reaching up and helping the cylinder rotate. A nice SAA clone in .45 Colt, ten rounds tops, both too tight. My Open Top 1872 clones, my Richards/Mason conversions in .44 Colt and Sue's 1851 Conversions replicas in .38 spl ran flawlessly with black Then I bought a Cimarron SAA clone in the black powder configuration with 4 clicks and the screw held base pin with a cylinder bushing in .44 w.c.f. and behold, it functions with BP. Even better when using Dick Dastardly's Big Lube bullet mould.

Most of those are gone now because we stopped shooting cowboy matches. Oops, drifting.
 

Petrol & Powder

Well-Known Member
I'm not sure I understand the OP's question.

The OP wrote, "Will the oversized bullets cause issues in the long term?"

Why do the bullets need to be oversized?

The OP does state, ".... I was planning on shooting as cast, ..." but that doesn't preclude that the bullets COULD be sized to fit the cylinder throats. (Which would COMPLETELY eliminate this discussion and eliminate the problem)

The OP wrote," .....I slugged the bore and cylinder, and all is good there, but the cylinder is right around 0.357..." ?????

SO - SIZE THE BULLETS TO .0357" and BE DONE WITH IT !!!!

There is NO NEED to start reaming throats, worrying about "as cast" size of bullets or any other issues.
 

5shot

Active Member
I'm not sure I understand the OP's question.

The OP wrote, "Will the oversized bullets cause issues in the long term?"

Why do the bullets need to be oversized?

The OP does state, ".... I was planning on shooting as cast, ..." but that doesn't preclude that the bullets COULD be sized to fit the cylinder throats. (Which would COMPLETELY eliminate this discussion and eliminate the problem)

The OP wrote," .....I slugged the bore and cylinder, and all is good there, but the cylinder is right around 0.357..." ?????

SO - SIZE THE BULLETS TO .0357" and BE DONE WITH IT !!!!

There is NO NEED to start reaming throats, worrying about "as cast" size of bullets or any other issues.
They come out of the mold oversize, and I would rather not size. Thus, the as cast bullet is larger than the cylinder throats, but will easily fit in the chambers.
 

RBHarter

West Central AR
The operative solution is to think of the throats as really fast sizing dies .

I shot 1000s of as cast .454s through .453 throats in to .452 barrels .
Now I have 1 that won't chamber a .454 so I have to size .4525/.453 for the throat into the .451 barrel .

I haven't had any issue with a .454 into a .450 groove in a carbine .
 

Petrol & Powder

Well-Known Member
They come out of the mold oversize, and I would rather not size. Thus, the as cast bullet is larger than the cylinder throats, but will easily fit in the chambers.
I think you've answered your own question.
"...I would rather not size..."

There are two paths here:
1. Shoot them "as cast".
2. Size them to match the diameter of the throat.

You don't say how oversized they are but you do say they will fit the chamber. So, I'm going to assume they are not grossly oversized in the "as cast" condition. You can simply lube them and shoot them in the unsized condition. As pointed out, the throats will simply act as a really fast sizing die. Many reloaders/shooters prefer to shoot bullets "as cast" because it simplifies the reloading process. This works well as long as the as cast diameter isn't grossly oversized.


However, there are advantages to sizing cast bullets in some situations. If the the bullet is too large in its "as cast" condition, sizing may be required. Sizing can also help if the mold isn't dropping consistent bullets. And if you're not tumble lubing, why not size and apply bullet lube in one operation?
 

5shot

Active Member
I think you've answered your own question.
"...I would rather not size..."

There are two paths here:
1. Shoot them "as cast".
2. Size them to match the diameter of the throat.

You don't say how oversized they are but you do say they will fit the chamber. So, I'm going to assume they are not grossly oversized in the "as cast" condition. You can simply lube them and shoot them in the unsized condition. As pointed out, the throats will simply act as a really fast sizing die. Many reloaders/shooters prefer to shoot bullets "as cast" because it simplifies the reloading process. This works well as long as the as cast diameter isn't grossly oversized.


However, there are advantages to sizing cast bullets in some situations. If the the bullet is too large in its "as cast" condition, sizing may be required. Sizing can also help if the mold isn't dropping consistent bullets. And if you're not tumble lubing, why not size and apply bullet lube in one operation?


The only real question I had, which has kind of been answered, is whether or not the cylinder and frame would be damaged by long term shooting of bullets that would not fit through the throats. I do know how a bullet "Should" fit in a revolver, and I know that if the rounds don't chamber, then sizing is required.