.360 diameter

[salvadore]

That's what my wadcutters measure out of the mold. I've been reading the posts about various tumble lubes ie 45/45/10, JPW, Lee alox etc. I wanted to try the lubes and not bother with sizing. The throats on my m-28 are .358, the loads would be mid to full range .38 spec. pressures. Will this be a problem?

[runfiverun]

nope.. unless your chambers are real tight or your front drive band jams into the cylinder throats.
I run into an oversize issue similar to this with powder coated bullets.
so I set up my 38 cal taper crimp die and run the loaded round into it until it allowed the rounds to drop freely into the cylinders then locked it down.

as far as the pressure .002 will maybe add 400 psi.

[quail4jake]

You will do better with that oversize situation than sizing down to slip fit in the throats and it will help consistency if you have throats that aren't all quite equal.

[Outpost75]

As long as long as the rounds chamber without forcing, I would try them and see how they shoot.

You may be pleasantly surprised.

[tazman]

Shoot them if they chamber. No problem.

[DougGuy]

Load one and mic the shoulder of the case just behind the crimp. SAAMI specs for chamber dimensions in this area are .381" just before the chamfer/ball seat most 357 cylinders will not chamber a .360" boolit because A. The cylinder throats will not permit seating of the round fully in the chamber, and B. The chamber itself will not accept a boolit that causes the assembled case diameter to be larger than .381" in the shoulder/case mouth after assembly.

If you don't have a pin gage to measure the chambers with in the cylinder, you can push one of the boolits into an unprimed case upside down and load it flush to the case mouth like a 38 Spl wadcutter, this will allow you to check the chambers and see if they will accept loaded rounds without the interference of the cylinder throat.

It won't do any good to ream the cylinder throats to accept .360" boolits if the chambers themselves will not accept the loaded case. It serves no purpose to size the boolit larger than cylinder throat diameter since boolits fired will exit the front of the throats at throat diameter. All that does is raise pressures needlessly and smear the sides of the boolit as it is squeezed into the throats.



You will do better with that oversize situation than sizing down to slip fit in the throats and it will help consistency if you have throats that aren't all quite equal.

Sizing larger will NOT remedy this situation. Uneven throats create uneven resistance which creates uneven pressures which causes the gun to recoil differently in the shooter's hands from shot to shot. This will ENSURE that the boolits will not fly to the same point of aim from shot to shot. The most important part of the cylinder, is having the throats and chambers EVENLY sized.



as far as the pressure .002 will maybe add 400 psi.

Try 5,000psi for a magnum level cartridge that is at a max loading and an alloy of COWW hardness entering a throat that is .002" smaller than boolit diameter.

**I got this information from an elderly, VERY well regarded and published retired gunsmith who I cannot contact to verify due to the fact that the Mods (nazis) on the forum which he frequents permbanned me for basically sharing my knowledge of cylinders and throats. I take his information to be factual and verifiable by pressure testing as he had the results to back it up. I just cannot post it here if I had it, it is copyrighted information.

It depends more on alloy and how fast the powder burn rate is, how much excess pressure is developed. I think we can all agree on the fact that the less resistance developed in the cylinder throat, the less pressure rise will be. Softer alloy = less resistance. Slower burning powder = less spike, lesser charges = less rise, etc..

[Wayne Smith]

I size my .38/357 to .358 because a .359 is difficult to push into the chambers of my S&W's.

[Outpost75]

It is also true that some .38/.357 revolver chambers just run sloppy.

I have a Ruger Vaquero 4-5/8" .357 with .360 cylinder throats and .384 chambers which accepts most .38 S&W rounds straight-up and will chamber the rest of them if I run them through a Lee .38 Super factory crimp die first... Yeah and it shoots .38 Super also!

[DougGuy]

It is also true that some .38/.357 revolver chambers just run sloppy.

I have a Ruger Vaquero 4-5/8" .357 with .360 cylinder throats and .384 chambers which accepts most .38 S&W rounds straight-up and will chamber the rest of them if I run them through a Lee .38 Super factory crimp die first... Yeah and it shoots .38 Super also!

This is exactly why I suggest (in the absence of pin gages) loading a dummy boolit upside down and see if it will fit in the chambers.

[runfiverun]

your not gonna gain that much pressure, you'd never be able to size a boolit if it took 5,000 psi. to squish it down .002

[DougGuy]

your not gonna gain that much pressure, you'd never be able to size a boolit if it took 5,000 psi. to squish it down .002

That's totally different from a pressure spike on ignition of powder. 9mm runs at 35,000psi, but as little as .010" or .020" boolit setback can send pressure through the roof.. 35,000psi to 60,000psi in a nanosecond..

[mdi]

Just another thought and FWIW; since the ID of a case is tapered, deep seating a .360" bullet may bulge the case enough so the cartridge won't chamber. BTDT. My "quick fix was to seat the bullet shallower, with perhaps 3/16" to 1/4" of bullet out of the case, as long as it fit the cylinder's length. Obviously it wasn't a problem with all cases so sorting by headstamp helped...

[runfiverun]

set back in a 9mm will destroy the gun especially if combined with a powder like titegroup.

swaging down a bullet or boolit is completely different.
you do get a spike when the engraving takes place.
that spike however drops off then the pressure climbs due to gas volume being higher than the available space.
one of the high velocity tricks with a too slow powder is to time the engraving spike with the pressure increase to get the slower powder up to pressure so it will burn more efficiently.

that isn't the easiest thing in the world to do and quite often you have to trick the ignition system into also bumping the pressure before the spike too.
there are a few way's to do that, one of them is jamming the lands, another one is using a filler to trick the system into thinking it is in a smaller case, and still another is to use a 2 part powder load.
a combination of them all is used in an effort to get that last few FPS and 5,000 psi for a clean powder burn.
if just using .002 more diameter was the easiest trick it would be used more often, and the HV designs would all have more lead displacement areas cut into them to compensate for that extra movement than they do.

[tazman]

That's totally different from a pressure spike on ignition of powder. 9mm runs at 35,000psi, but as little as .010" or .020" boolit setback can send pressure through the roof.. 35,000psi to 60,000psi in a nanosecond..

The OP is talking about using mid to full power 38 special loads in a model 28 (probably S&W which is a 357 magnum). I don't think 9mm problems apply here.

[DougGuy]

The OP is talking about using mid to full power 38 special loads in a model 28 (probably S&W which is a 357 magnum). I don't think 9mm problems apply here.

Yes taz, but that comment was my comeback to run5's comment..

[runfiverun]

and it is somewhat valid.
but we are dealing with a completely different part of the sequence here.

and we are also using different systems [rounds] to make our point so it's probably more of an apples to oranges comparison.
I will make one more point and let it go at that.

years back many target guns were revolvers.
the good high end ones Colt and S&W both were made with barrels in the 354-355 area.
their cylinders were made to take 358 bullet diameters [but ended at .356 at the mouth] that is far more than .002 down.
a 5-K increase would push a light target load well over the 38 specials 19-K pressure zone.
I'm pretty sure the hundreds of thousands of rounds those target guns fired would have finished off enough of them by now to have made the pressure spike a well known phenomenon.

[salvadore]

Call the Air Marshals.....just kiddin, thanks for the info.

[copdills]

Shoot them if they chamber. No problem.

sounds like a plan