Max. Boolit Diameter in .357 Mag.

[Motor]

I have looked at the SAMMI spec but want some real world feed back. I figure if I get at least a few good replies I will be able to decide what boolit size die to get.

The question: What is the largest cast boolit you have used and still fit without fuss in your .357 Mag cylinder? (Without using a Lee FCD also.)

I don't want to hear about slugging and all that. If I was only loading for one revolver that would be fine. My cast loads are light and my boolits are soft enough that if they are a little over the "recommended" diameter they will just fill the bore better.

Again, I know the specs including case wall thickness I just want some "real" feedback.
Thanks,
Motor

[DougGuy]

Actually this is a hard question to answer. You are saying 1. I don't want to measure my cylinder throats, and 2. what's the biggest boolit I can fit in there?

Very difficult to answer the question IF YOU DON'T KNOW HOW BIG THE HOLE IS..

Suppose 5 people reply, they all own S&W. You own a Ruger. The answer to the question is going to be DIFFERENT from one to the other, and you need to know what YOUR cylinder throats measure, not what size boolit 5 other people's cylinder throats will chamber.

[Motor]

I'm a machinist and understand your point. However there are specs for those cylinders and it should not matter who made them none should be smaller than minimum spec.

Even having the numbers though don't always add up because of "unseen" things like lube and slight boolit misalignment etc.

After doing some on line shopping though it does seem a .358" Lee push through size die is the largest they make. Still I have every ability to make it any size I want. So what diameter boolits are you guys using?

[Bzcraig]

I have a Lee .358 size die I open to .359 and that is what goes in my 357mag

[Motor]

I have a Lee .358 size die I open to .359 and that is what goes in my 357mag

That looks like the way to go. I have used boolits from this mold before without any problem but they were cast soft at 8bhn. When I did my latest batch I made the harder (12bhn) and it seems to have had an effect on what diameter they dropped at. They are .360 some almost .361

I am quickly learning that revolver cylinders are not a generous in size as auto chambers and not as tolerant to oversize boolits.

I'll have to get the .358" size dia. I'll try some at .358" to see how they perform first before doing any mod to the die.

Thanks for the feedback.

Motor

[ReloaderEd]

Let us answer a few simple questions first.
1. How does your .357 magnum shoot with factory .357 magnum ammo? Good yes bad no.
2. With 38 specials?
3. Is there one particular type or manufacture That shoots the best?
If any of rhe qusruons are answered yes that should tell you what bullet diameter sizer die you will want to use.
Be safe.

[DougGuy]

I'm a machinist and understand your point. However there are specs for those cylinders and it should not matter who made them none should be smaller than minimum spec.

Even having the numbers though don't always add up because of "unseen" things like lube and slight boolit misalignment etc.

After doing some on line shopping though it does seem a .358" Lee push through size die is the largest they make. Still I have every ability to make it any size I want. So what diameter boolits are you guys using?

Specs? Dude, you gotta be kidding me.. Okay, for starters, a few basic FACTS might be in order. If you have a cylinder, WITH tight throats, as in undersize, as in MANY Ruger cylinders are shipped with undersize throats, ok, following me so far? And you just "decide" on a .358" boolit size, like out of the BLUE, and you load 50rds, and none of them will chamber fully, because you never bothered to check the throat sizes, happens quite often! This, is a known FACT, that a .358" or a .359" boolit WILL NOT FIT IN A CYLINDER WITH .357" THROATS!

Not going to tell me you are a machinist and turn a blind eye to measuring a critical item like the cylinder throat in choosing a boolit size for the gun.

I do cylinder reaming and honing as a business. I do several cylinders EVERY WEEK. S&W, Ruger, People send them because the boolit they want to shoot won't go in the front of the cylinder. When they get them back, the sample boolits they send with them, will slide into the front of the cylinder with finger pressure. THIS, is what you want yours to do.

I know how uneven, how undersize, factory cylinder throats can be because I see a lot of them. But that's fine, go ahead and pick whatever boolit you think might work.

[warf73]

a .358" or a .359" boolit WILL NOT FIT IN A CYLINDER WITH .357" THROATS
If you push really really hard it might :)

But back on topic you should really measure you gun, just because a .359" works in my S&W doesn't mean it will work in my sp101(and it won't).
Factory specs can run .356~.359 now pic your poison for your revovler.

[TCLouis]

I have a .356", .357", .358", .359" and .360" sizing die

.356" for 389/9mm stuff and .360" for all other 35 caliber shooting irons, lever, single or six shot!

[Charlie U.]

.356" for 389/9mm stuff and .360" for all other 35 caliber shooting irons, lever, single or six shot!

I also have done pretty well using .359 and .360 for my cast wadcutter loads.

[Motor]

[QUOTE=DougGuy;2957852]Specs? Dude, you gotta be kidding me.. Okay, for starters, a few basic FACTS might be in order. If you have a cylinder, WITH tight throats, as in undersize, as in MANY Ruger cylinders are shipped with undersize throats, ok, following me so far? And you just "decide" on a .358" boolit size, like out of the BLUE, and you load 50rds, and none of them will chamber fully, because you never bothered to check the throat sizes, happens quite often! This, is a known FACT, that a .358" or a .359" boolit WILL NOT FIT IN A CYLINDER WITH .357" THROATS!

Not going to tell me you are a machinist and turn a blind eye to measuring a critical item like the cylinder throat in choosing a boolit size for the gun.

I do cylinder reaming and honing as a business. I do several cylinders EVERY WEEK. S&W, Ruger, People send them because the boolit they want to shoot won't go in the front of the cylinder. When they get them back, the sample boolits they send with them, will slide into the front of the cylinder with finger pressure. THIS, is what you want yours to do.

I know how uneven, how undersize, factory cylinder throats can be because I see a lot of them. But that's fine, go ahead and pick whatever boolit you think might work.

Very informative post. Thanks.

[Motor]

Thanks guys.

As I said in post #5 bollits from this mold cast at 8bhn worked just fine. It just took me by suprise that a couple thou would make such a difference. I'm used to casting for my semi autos. They are not picky.

I will measure the cylinders. I have to do the 41mag too.

[gray wolf]

I don't think DougGuy's info was insulting, Revolvers are not semi autos and he was just pointing out some ( perhaps overlooked things ) Sometimes it can be enlightening to measure cylinder throats. No offense, just saying.

[Motor]

I don't think DougGuy's info was insulting, Revolvers are not semi autos and he was just pointing out some ( perhaps overlooked things ) Sometimes it can be enlightening to measure cylinder throats. No offense, just saying.

Yes his post is informative.

(Edited to remove off topic comments.)

[DougGuy]

OP, offensive comment removed.

Do you have access to a set of minus pin gages? This is the best way to gage your cylinder throats. It will also show you an elliptical throat if you can look past one side of the gage and sunlight will pass through it.

Depending on what boolit style you choose, the driving band of the boolit has to fit in the cylinder throat or the loaded round won't chamber without excessive force. Do NOT seat a boolit deeper in the case to avoid this situation without correcting any load data to accomodate lessened case capacity.

In a perfect world, the boolit passes through several stages of mechanical "guidance" before leaving the muzzle, and each stage of this journey would be getting progressively smaller so the boolit fits tightly in each stage. If any one step is smaller than the subsequent steps, problems begin. Normally, the undersize parts to look at and correct would be the cylinder throats, and as often as not, the area of the barrel that threads into the frame. Manufacturers often torque the barrel tight enough to cause a major constriction in this area, we simply call it "thread choke." Either way, it serves as a sizing die to reduce the diameter of the boolit and introduce poor groups, leading, and a general disdain of the firearm in question.

Being a machinist, with access to pin gages, it is easy enough to find one that fits in the bore and see if it slides smoothly from one end to the other and comes through the forcing cone. Without pin gages, my favorite way to check for thread choke is with a tightly patched cleaning jag in a clean dry bore. As you push it towards the forcing cone, you can "feel" any bit of tightness at the threads. You can also LOOK with your eyes down the bore and see a circular distortion in the bore where it meets the frame.

If the bore is free of thread choke, and you have pin gaged the lands, you can go look up SAAMI specs for the land and groove diameters and blindly assume the barrel is made according to specs, OR you can slug the bore and measure the slug to get an idea what it's diameter is. This is actually the lesser critical measurement, since all you really need to do is make sure the boolit is greater than that diameter.

If the cylinder throats are undersize, again they will act as a sizing die and whatever their diameter is, the boolit will exit the cylinder fire-fitted to this diameter. Yes there is enough pressure in the .357 to swage boolits to the cylinder throats. This is why the throat diameters are critical, because no matter what boolit diameter you feed into them, you get out the front, a boolit that is the exact size as the throats.

Often there are several different throat diameters in the same cylinder. As manufacturers replace worn tooling, a new reamer will produce a larger diameter throat than a worn one. Ruger used to gang ream 3x at a time using a Hitachi machine that had 3 cutters. As these cutters wore, they would replace them at random, not all at once, so you often have 3 pairs of cylinder throats, with different diameters. What this does, and why it is critical to have the throats all consistent, it changes the pressure generated by the round being fired, which changes the recoil impulse accordingly, and a tight throat will shoot to a different point of impact than a larger throat, simply because more pressure or less pressure affects how the gun recoils in the shooter's hands.

Commonly, us cast boolit shooters use boolits larger than factory ammo is loaded with, and manufacturers don't cater to our needs, they cater to factory made ammo and in most cases, loosely adhere to SAAMI specs however we have all seen barrels and cylinders that were shipped, nowhere near conforming to those specs, hence they are guesswork at best how closely any given firearm matches specs.

For our needs, we select a boolit style we want to use, we slug the bore and choose a diameter .001" or more greater than bore diameter. Then, rather than assume the cylinder will accommodate not only loaded ammo with chosen boolit, but firing the chosen booit without resizing it, we measure the throats and if they are undersized, or inconsistent, we either ream them ourselves or send them to a smith or someone like myself to have them reamed to fit the boolit diameter that we want to use. This is the most common path to getting our revolvers to shoot like we want them to without leading. Making sure the revolver and it's parts are "dimensinally correct" is half the battle, but it's an important and most often overlooked half. The other half is developing loads that work well, are accurate, and don't lead the bore.

It's very common for me to get a cylinder in that the shooter wants to use a .360" boolit because they want to shoot the same load in a lever gun which has a larger bore diameter than the revolver. I can tell you from experience that maybe 1 out of 500 .357 cylinders will even chamber a loaded round with .360" boolits. This diameter is well above SAAMI specs but hey it works and it does what the shooter wants it to do. Nuf said.

Almost every hand loader has and uses sizing dies. Why? Because they want a specific boolit size that fits their purposes. Why should you want to gage your cylinder throats? So you can fit them to the boolit you want to shoot. The cylinder is just a guide, the cylinder throat presents the boolit to the barrel. It is a tool, just one part of the process of firing. Unless you already have oversized cylinder throats, the proper way to address this component, is to make it conform to the boolit, NOT the other way around.

[Motor]

DougGuy, Thanks for yet another informative post.

I've worked in 4 different fields of manufacturing over the last 27 years and none of them tolerated out of spec. product. I had no idea that firearms were any different.

I have shot many cast boolits from my .357s but only recently begun to cast my own. Sometimes you experts, and I say that respectfuly, only see the big picture.

I loaded 100 rounds. 55 fit 45 did not. The remaining unloaded boolits measure .360 to .361 The ones that don't fit in the cylinder start in but then get tight. I can see on the cases where they rub the cylinder wall.

The ones that do fit shot just fine. They are accurate and do not lead my barrel. Therefor I have to believe that .360 is just about max for my cylinders. But since I've been successfully shooting comertial cast .358s that is what size boolit size die I am going to get.

I should have done my measuring before posting the question but then I would not have learned so much.

Motor

[NoAngel]

I have a .359 size die I polished a little to .3595 or so. It goes in all my .357 mag loads.

[DougGuy]

I guess you could pull the ones that will not chamber and run them through the sizer. A .358" sizer is probably the most common size used for the caliber but some cylinders won't chamber those even. Some cylinders are actually .357" as advertised. If you have a known .358" boolit, you can use it for a pin gage by pushing it into the front of the cylinder throats. It should go with finger pressure, you should not have to force it. It's fine if it goes with very little effort.

Using a .358" sizer should be all you need provided the boolits go into the cylinder throats, and it wouldn't hurt matters if they were loose fitting enough to allow for age hardening cast boolits, which can easily pickup .0003" - .0006" as they harden off in the weeks post casting, depending on your alloy and treatment methods. Keep this in mind if you decide to lap a sizer to let your boolits fit snugly in the throats. In a month or two, again depending on your alloy and any heat treating or water dropping, they may not chamber!

Pretty much you have to take each gun as an individual. Ruger barrels for instance, are very very consistent, the .45 barrels are right at .451" but the cylinder throats are all over the map. Mostly undersized at .4505" and .451" I have pinned a couple of roll marked Bisley cylinders with .450" throats. The good thing about it, they are undersized and not oversized, and that can be easily remedied.

[Motor]

I ran the ones that did not fit through a Lee FCD with the crimp sleeve backed off. They fit now, but I know I may have lost a good bit of neck tension. I kept them seperated so I can do a side by side comparasion to see just what ill effect it may have.

I always strongly recomend to others never to use a FCD with cast or plated boolits and here I am doing it myself.:groner:

Thanks for the insite. I will take your advice. I have a new .410 mold that has not seen any hot metal yet and a 3 screw 41mag Ruger to fit them to.

[Piedmont]

Chambering ability is not all about cylinder throat size. You could have large chambers and tight throats and if the bullet was not seated with the front band out of the case it would chamber a possibly much larger bullet than the cylinder throat size. Most revolver designs have a full diameter front band that is past the crimp groove. Now we may run into the cone past the end of the chamber when crimped in the crimp groove if the bullet diameter is too large and get chambering difficulties. Seat that same bullet deeper, even if it is too large to push through the cylinder throat with hand pressure and if the chamber will accommodate it, there will be no chambering difficulties.

This is the reason Lyman messed with the front band on Elmer's bullets and other bullets, making them smaller than the other bands. No matter what the rest of the bullet was sized to the round would chamber because that band sticking out of the case was undersized. This cut down on complaints and cut down on returned molds. It often cut down on accuracy too! The proper solution is a full diameter front band, a selection of bullet sizing dies, and an understanding of the fitting process.

[dubber123]

I have a Freedom Arms .357, a brand often noted for it's tight tolerances, and much to my surprise, it will EASILY chamber a .360" boolit in a loaded round. This however is not the diameter the gun needs. As Doug has expressed, you really need to know your groove dimension, and your cylinder throat numbers. Odds are good that you will get by just fine with .358", but measuring will tell. Doug had to ream a .357 revolver of mine to .359" to compensate for a looser than normal barrel, and it shoots wonderfully now.