357, 358 or other for 38/357 cast?

I have generally sized my 38/357's at 358. I did try some at 357 a while back and I couldn't seem to group very well. I then did some reading and the Lyman mould I was using at that time was noted for its lack of accuracy. So it was one of those, is this or is it that issues.

I now have a new NOE mould and have started to size these castings at 358 with a Lee sizer and will PC them.

I am shooting these out of multiple K and N frames, Rugers and a Colt. What do you size your 38's at and why? And if you PC, do you resize after you PC and why?

Thanks

I size mine to .358 for my Ruger Black Hawk in 357 Mag

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Cylinder dimensions vary between guns due to normal manufacturing tolerance. Best is to check each revolver with pin gages and size bullets to that diameter or 0.001" under.

I slug the barrel for the groove size and check to see if that size passes through the cylinder throats. If it does, then I size to the cylinder throats. If it doesn't, then the cylinder throats need to be made larger. Just enough to be about .002 larger than the groove size.
I have been lucky in that all my revolvers have groove dimensions that are slightly smaller than the cylinder throats on any given gun. They will all chamber .358 boolits even though a couple of them have throats slightly smaller than that. They still shoot well because the boolit fits the barrel well even after being sized down by the cylinder throats.
No leading and good accuracy this way.

Outpost 75 is correct about the pin gauges. I don't have pin gauges so I use a bullet/boolit of known size(I do have micrometers) and see how it fits the cylinder throats.
It is a cheap way to find out but it works for me.

For almost all of my 38/357/9mm I size to .358.

I have one S&W M10 PPC revolver that prefers 357. I size and load a specific load for that one revolver.

If it didn't shoot so well I'd get rid of it, but....

I shoot my Colt Whitetailer with 360’s and WOW it never shot better!!

My Black hawk likes 358/359 better.

Gotta measure the front of the cylinder. If its too big or too small
For the size you use you need to change for best reaults.

CW

I was sizing to .358" but getting some leading. I made two changes about the same time so I can't specifically attribute the improvement to one change.

1. I changed out the expander (powder funnel) on my Dillon press. The Dillon expanders were replaced with a custom made powder funnels from Lathesmith.
2. I sized my bullets to .357"

The Dillon powder funnels do not expand the casings enough for cast bullets. The Lathesmith powder funnels size the casing to the correct diameter, they size them to the correct depth and they incorporate the Lyman "M" die style step instead of a basic flare.
HUGE IMPROVEMENT !

The .357" sizing diameter works for all of my Ruger and S&W revolvers. Colt is a story for another day.


My appraisal of the situation is that the Dillon expander was not expanding the casings enough. Some bullets were being swaged down and they weren't being swaged down uniformly. The initial sizing of .358" may have helped that situation but it didn't result in consistent bullet diameters. This was confirmed when I measured pulled bullets and found most with diameters less than the original .358" .

Most of my DA revolvers have cylinder throats close to .357", so the old advice to size to the cylinder throat may be in play there as well.

Yes definitely you size last.

Anything that changes the diameter is a change.. a change from whats wanted.

Revolvers bring more to the table in proper cast bullet sizing. But generally speaking .001 to as much as maybe .004/.005 are used for some calibers with lead bullets! Conventional lubed Lead is not jacketed. PC while giving a jacket still isnt the same as a copper or brass clad bullet. But pc also works best a few thousandths larger than the bore.

Whats actually best is up the the gun and they of coarse cannot speak words but if you know and understand what they do tell you you can find the proper diameter.

CW

Use the diameter bullet that fits your gun best. I have used cast bullets in 38/357 revolvers from .357" to .359"+, all depending on the gun's dimensions.

Perhaps we need a sticky on fitting bullets to the gun?

Quote:

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Originally Posted by Petrol & Powder

I was sizing to .358" but getting some leading. I made two changes about the same time so I can't specifically attribute the improvement to one change.

1. I changed out the expander (powder funnel) on my Dillon press. The Dillon expanders were replaced with a custom made powder funnels from Lathesmith.
2. I sized my bullets to .357"

The Dillon powder funnels do not expand the casings enough for cast bullets. The Lathesmith powder funnels size the casing to the correct diameter, they size them to the correct depth and they incorporate the Lyman "M" die style step instead of a basic flare.
HUGE IMPROVEMENT !

The .357" sizing diameter works for all of my Ruger and S&W revolvers. Colt is a story for another day.


My appraisal of the situation is that the Dillon expander was not expanding the casings enough. Some bullets were being swaged down and they weren't being swaged down uniformly. The initial sizing of .358" may have helped that situation but it didn't result in consistent bullet diameters. This was confirmed when I measured pulled bullets and found most with diameters less than the original .358" .

Most of my DA revolvers have cylinder throats close to .357", so the old advice to size to the cylinder throat may be in play there as well.

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Glad to find out about the Dillon expander. I've been using my Dillon S/D for years with no leading probs on my old Colt Trooper since it has a .354 bore. I recently bought that 5 inch Smith Model 27 I've been wanting and I may have a leading problem with it with the existing funnel. I'm gonna let Veral measure the bore slug when I order another 160gr. FN mold from him, but my throats on the Smith are .3582 in every bore. Those little Starrett small hole gages are the tits.

I'm a huge fan of Dillon products but their powder funnels are set up for jacketed bullets. The Dillon funnel doesn't expand the casings enough and it puts a flare on the case mouth. You can adjust the die so that the flare is minimal and just enough to accept the bullet but you can't do anything about the diameter of the expander.
Lathesmith can make a custom powder funnel (powder through expander) that has the proper dimensions AND incorporates the Lyman "M" style "step" instead of the trumpet shaped flare. It really takes you to the next level.
The custom expander reaches down to the correct depth and expands the case to the proper diameter. The "M" die style step makes is also far more cast bullet friendly than the basic flare.
I can't speak to the SDB but the funnels for the 550 are awesome.

I don't size pb boolits ,lee 158mold .size gc boolits 358 for my win.

Sizing may not be too important when using them in a revolver, but is very important for a lever action rifle. If those cast bullets are even slightly over-sized, they will bulge the case just enough that the cartridge will not pass through the cartridge guides in the rifle. Experience is a very good teacher.

Make a dummy round to check feeding etc .my win ain't very fussy.

I had a LEE 148gr. wadcutter TL mold. When I first started casting the wadcutters I sized them .357. The groups from my 2 PPC revolvers weren't
good at all. I then sized them .358 and it was as different as night and day.

Nick10Ring@aol.com

Normal size for my guns in 38 and 357 is .357. A 92 Winchester I had rebarreled to 357 in the early 60s needs 358. A six inch Security Six from the first run groups better than my old K38 if I use .356 and 13.5/2400. They all have preferences.

I size all of mine .358 which works great in my Marlin and SW 686s.

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Boolits that drop from the mould close to .357" get sized in the .357" marked die .

Boolits that drop over .357" , like NOE's 360-160-WC PB and others , go through the sizer die. marked .358" .

I don't notice any difference in accuracy or leading in my handguns .
Two 38 specials ( K & J frame S&W's) , two 357 magnums (S&W N-frame & Ruger Blackhawk).

The NOE 360-160-WC PB , sized .358 is the accuracy champion in all of them .

Gary

I can attest. I have a xl650 and am working through loading cast for 9mm. I had issues with the boolits swaging down using the stock powder funnel, until I machined one up that has an OD of .356 and a sharper taper than stock. Now my sized boolits go in and come out the same size. I switch back to the oem one for jacketed because the neck tension isn't enough with the custom funnel.

Quote:

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Originally Posted by mdi

Use the diameter bullet that fits your gun best. I have used cast bullets in 38/357 revolvers from .357" to .359"+, all depending on the gun's dimensions.

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Well, it HAS to at least chamber, so you can't fit a .358" into a .357" throat unless the boolit is seated deep enough that it doesn't enter the throat, or the interference would stop it from chambering. So the advice of using what fits the gun is correct in the mathematical sense.

Quote:

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Originally Posted by mdi

Perhaps we need a sticky on fitting bullets to the gun?

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This is a flawed approach at best. Reason being that the BOOLIT is the important dimension here, NOT THE GUN.

The CORRECT approach would be to fit the boolit to the bore, with .001" minimum interference, usually .001" to .002" over groove diameter works best, THEN you size the throats of a a revolver .0005" to .001" greater than the boolit diameter. Same with an autoloader, size the throat .0005" to .001" over the boolit diameter you want to shoot, then size to that dimension and it will work every time. This INSURES that the boolit will pass into the bore, sized as intended, not as the throat sized it.

The other reason you should not size to fit throats, is if the throat diameters are inconsistent. Most Rugers show considerable inconsistencies in cylinder throats. Most of the new model 3-digit prefix medium frame revolvers have excellent consistency in the cylinder throat diameters. Most S&W are pretty consistent. However, a great number of revolver cylinders are not sufficiently sized over the groove diameter of the barrel for best performance with cast boolits. Most S&W are consistent, many are .357" and the groove diameter is .357" which is not optimum for cast.

You cannot size to uneven throats.

The best workaround for this, if you don't want to have the cylinder throat diameters corrected, is to use a soft enough alloy over a stiff enough charge that the boolit will obturate or bump up and seal very well in the bore.

You can size and load all the .358" ~ .35x" diameter boolits you want to, but they are going to exit the front of the cylinder, AT THROAT DIAMETER! Many that size to .358" are not aware that they are firing those boolits through a multi-port sizing die. If you can't push your finished and sized boolits into the front of the cylinder, by hand, with light finger pressure, they they most assuredly are not exiting the cylinder the same size upon firing, as when you loaded them. Simple as that. You cannot force a cast boolit through a smaller orifice and expect it to pass with no change in dimension.

Quote:

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Originally Posted by Rcmaveric

I size mine to .358 for my Ruger Black Hawk in 357 Mag

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Same here.

Quote:

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Originally Posted by tazman

I slug the barrel for the groove size and check to see if that size passes through the cylinder throats. If it does, then I size to the cylinder throats. If it doesn't, then the cylinder throats need to be made larger. Just enough to be about .002 larger than the groove size.
I have been lucky in that all my revolvers have groove dimensions that are slightly smaller than the cylinder throats on any given gun. They will all chamber .358 boolits even though a couple of them have throats slightly smaller than that. They still shoot well because the boolit fits the barrel well even after being sized down by the cylinder throats.
No leading and good accuracy this way.

Outpost 75 is correct about the pin gauges. I don't have pin gauges so I use a bullet/boolit of known size(I do have micrometers) and see how it fits the cylinder throats.
It is a cheap way to find out but it works for me.

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I did'nt realize just how reasonable pin gages wer or how much they helped the process until I bought some for my revolvers. IIRC I paid something like $3 each for mine and you don't have to buy an entire set to do what we want to do.
I have been getting by with the same thing you are with regards to my 686. It has .357 throats and barrel but it shoots 180gr Cast Performance .358 GC boolits really well-probably because of the gas check.

I don't have pin gauges. I use cast boolits.
I use them as cast. With a bit of oil in each throat I push one boolit through each throat. Measure. This gives me the sizes of the throats.
Using the largest throat I size a few boolits. I then load them in cases. Try these dummy rounds in all the chambers. If they fit the chamber I size to that diameter. I get no leading and very fine accuracy.
I also slug the barrel and have been lucky that the bore was always a few thou under throat dia. In my Dan Wesson 357 it likes them at 358.
My Ruger Redhawk and SBH like them at .430.
I load cast in some of my rifles. These I try to fit the boolit to throat diameter or as close as I can and still chamber.
In my Marlin 1894 44 Mag this gets boolits to .432. In the Mosin Nagant that's about .315.
Both shoot them well.
Leo

when I started loading and casting in 72 I bought a .357 h&i die still using it so it could be .358 by now. have used the bullets in rugers, colts, smiths and others with no problems. as long as the bullets shot as good as I can hold and don't lead I call it good. I don't do all this pin measuring.

Pin gage measuring is not a cure for all diseases but it gives a good starting point for a new gun that you are going to order a mold for. I am a habitual gun trader and it gives me a starting point for a gun that I might not have a boolit to measure with.