Confused about seating and crimping 357 cast

[national86]

I'm a little confused about seating and crimping my lee C358-158SWC 158gr. bullet. All my .357 case are trimmed to 1.288. I'm using Lee reloading manual and Tite Group powder, the charge is 4.5 grains. When I first started to seat the bullet to 1.610 (in lee manual), it didn't look right. So then I did some searching on forums, and most said seat to to the crimp groove. If I seat to the crimp groove the OAL is 1.560. Now, if I seat to the crimp groove isn't that going to increase cup pressure.
Also so these rounds will be fired out of single action revolver.

[LE-28]

Your at minimum load with what you described.

You won't increase pressure enough to matter.

[reddog81]

Seat and crimp into the crimp groove. If those bullets are .358 diameter and you try to fit the long one into a cinder you might have a problem getting the cylinder to close. I don't see much of a crimp on either of those.

357 and 38 special have large amounts of empty case space. A slight variance in bullet seating isn't going to have much effect.

[Hammerhead]

I would seat a little deeper, so the case mouth is almost touching the far side of the crimp groove. A small change in OAL would be a very small change in pressure, and unless you're at/near max, it's not a concern.

That's some odd looking brass, what is it?

[steveno]

the crimp groove in the bullet determines the oal in a revolver

[Mike / Tx]

the crimp groove in the bullet determines the oal in a revolver

As steveno pointed out, you use the crimp groove to determine the depth your seating to in most cases.

I say most cases as there are some revolvers which have a shorter cylinder, or which are chambered shorter and as such will not allow some of the longer SWC bullets to be seated in the groove. In that case if your going to use them you would back off the load a few tenths and seat so that you crimp over the first driving band.

While this WILL work it isn't very conducive to accuracy nor use with some powders. This is why Ideal/Lyman reduced the length of the first driving band on the original Keith design.

For jacketed you seat and crimp to the cannalure location as well.

[TimSr]

Seat in the cannelure. That's what it's there for. Old manuals didn't even list an OAL for revolver cartridges. I suspect they only do now because of these non-cannelure plated bullts some people are using now.

[Real Gun]

What is more important than a few thousandths in COL is the quality of the crimp, so following the advice about seating till the case mouth is just shy of the forward edge of the groove allows the best "roll" to the crimp. This is more important on lead bullets so it doesn't take so much force to get the roll, given enough case length unsupported under the die.

[Unclenick]

National86,

You got confused. 1.610" is the SAAMI maximum COL for 44 Magnum, not 357 Magnum. 1.590" is the SAAMI maximum COL for 357 Magnum. 1.405" is the minimum COL given in the SAAMI drawing I linked to. You are only 0.030" below maximum. However, it appears from your image that you are not enough lower. You want the front (top) edge of the crimp groove to be just above the case mouth so that the crimp folds into the groove. That's what it is for.

If you don't crimp a revolver load, recoil drives the cylinder back against the case rims of the remaining cartridges in the cylinder abruptly, while inertia tries to hold the bullet where it is. The result is the gun and cases pull back from the remaining bullets a little more with each shot, leaving them sticking out too far. This can jam cylinder rotation. Lubricated lead bullets are particularly vulnerable to it, though with a light enough load and a heavy enough gun, the effect is minimized and may not be an issue. Still, you'll get more consistent performance from a well crimped load.

The reason pressure is not an issue is two-fold. One is that your load isn't very high, as already mentioned. The other is that you are using a blunt shaped bullet, which is short for its weight compared with, say, a round nose bullet. The powder has no idea where the tip of the bullet is, so it doesn't care about that. What affects the powder and pressure are the weight and hardness of the bullet and the amount of space the powder starts burning in. The latter is controlled by the distance from the inside bottom of the case to the bottom of the bullet. That's what matters. So, if a COL of one loading is 0.1" shorter than another, but the bullet is the same weight and hardness and is also 0.1" shorter in the first load, then the pressure is the same.

The usual way the size of the space is determined is by seating depth. Seating depth is:

Seating Depth = Case Length + Bullet Length – Cartridge Overall Length (COL)

If you have an established seating depth you can seat different bullet lengths to that same seating depth by adjusting their COL, where the bullet configuration allows. This is done by rearranging the above formula to solve the COL:

COL = Case Length + Bullet Length – Seating Depth

(Note that hardness needs to change a lot to matter. All cast and swaged bullets (BHN 5-30 with most between 9 and 18) are treated the same from this standpoint, while jacketed bullets (BHN 40) are the next harder step, and solid copper or brass or bronze bullets (BHN's up to 90 or so) are the next harder step after that.)

One of the confusing things about the SAAMI specs for the layman is that the dimensions are unilateral. This is a common engineering practice where an error in one direction is more consequential than in the other. We are all used to tolerances that are plus or minus some amount, which are used where the direction of the error has equal consequence. But in the case of, say, sizing a shaft for a sleeve bearing, making the shaft too small still lets you assemble and operate the machine even if it doesn't work or last well. But make the shaft too big, and you can't even assemble it, so too big is considered a more consequential error. To avoid that, the shaft diameter is given as its maximum critical not-to-exceed value, followed by a minus-only tolerance to set the minimum recommended size. The sleeve bearing is just the opposite, and the value its diameter is given on a drawing is its minimum critical size, followed by a plus-only tolerance to set the recommended maximum looseness of fit.

In cartridges and chambers, SAAMI does the same thing as the shaft and bearing. A cartridge that is too big won't chamber, or a chamber that is too small won't allow a correct size cartridge to chamber. So cartridge lengths and diameters are given as their critical maximum values with a minus tolerance, while chamber lengths and diameters are given at their critical minimum values with a plus tolerance for the maximum size range. Thus, when you see a value in load manual for a cartridge length, that is a not-to-exceed. The manuals seldom include the minus tolerance. Too many people read that as meaning they should subtract that number from the given number, so it causes confusion as they don't understand it is giving them a range. They could do the subtraction and provide it as minimum and maximum, but they don't do that either. So it causes confusion.

Another thing to be aware of is that the SAAMI maximum cartridge overall length is there to insure fit in magazines and cylinders. If your gun has extra room and you have a bullet you can seat out further to make more powder capacity, that's fine and you can use it if you have a bullet that can be seated out that far and still allows you to crimp.

[Jim Watson]

One of Elmer Keith's first bullet designs was Lyman 358429, meant for heavy .38 Special loads in S&W Outdoorsman. When the .357 Magnum came out, he found that it loaded too long for the cylinder, so he crimped over the front band in .357 brass. But he said it still shot better in the Magnum when loaded in .38 brass and crimped in the groove.

[Nick_C_S]

Put the calipers away and seat to the crimp groove . . . as has been thoroughly stated now.

My recipe for 158 LSWC's using TiteGroup is 4.6 grains. Yes, these are seated to the crimp groove They chronograph at 938 f/s through a 686 w/ 4" bbl. They don't develop much pressure; so at 4.5 grains, you're well in the safe neighborhood. (My case trim length is 1.275 - 1.282.)

Off the subject: My above loading of TiteGroup leads up my barrels something fierce. More so than a healthy dose of HS-6 that propels the same bullet (Missouri Bullet "357 Action" hard cast) more than 150 f/s faster. I believe TiteGroup runs really hot and tends to lay down lead. It was this loading (among others) that has convinced me that TiteGroup is not well suited for lead bullets.

[Unclenick]

Nick,

It's curious. I've heard several complaints about how hot Tightgroup shoots, though I've never used it myself. In QuickLOAD it shows your load getting about 931 fps, and pressure peaking at about 19,900 psi. Pretty good agreement to actual. Gaining 150 fps needs about 7.7 grains of HS-6 in that software, and raises the peak pressure just 1500 psi. (I'm curious if that's close to what you wound up with?)

Anyway, fouling is usually pressure-dependent. One difference in the two loads is QuickLOAD thinks the Tightgroup load pressure peaks before the bullet has cleared the case mouth, while the HS-6 load peaks afterward, when the bullet is in the chamber throat. That make me wonder if the Tightgroup load is expanding the bullet base beyond throat diameter before it enters the throat, where the HS-6 load is not. That may be the difference. There'd be more scraping of the TG bullet at the case mouth and squeezing it down into the throat will foul the throat more. Is that where you get the extra leading?

[mikld]

In my limited experience, seating a bullet to the crimp groove and ignoring book OAL is the way to reload for revolvers. The OAL listed in a manual (not the SAAMI specs) is what the test personnel got when they used a specific bullet. There is only one bullet design that seating depth is questionable and that's a Lyman .38/,.357 mold that produces a bullet with two crimp grooves (don't have that mold/bullet model number handy) and it's necessary to see which groove allows chambering in some revolvers...

[Real Gun]

One does have to be aware of and measure for the spec's maximum COL, better yet checking for chamber fit in the gun, unless having more than one gun which don't always accept the same ammo. That should leave a range within which the crimp will be well placed in the groove. The bullet nose shape may force some accommodation at a slightly shorter length or even be reserved for the shorter version of the cartridge, say 38 Special instead of 357 Magnum. I had some 32's that worked in 32 H&R but not the tight fit of the Ruger Single Seven in 327 Federal Magnum. Penn's version was slightly shorter than Missouri's.

[T. O'Heir]

"...in Lee manual..." Perfectly safe, but Lee tests nothing themselves. They use the powder maker's data. In this case Hodgdon's. Yes, the 1.610" OAL looks odd. And yes, that's the OAL given by Hodgdon for a cast 158. Dunno where they got that length. Max OAL for .357 is 1.590".
However, at 4.5 of Titegroup, that being the start load, but a fair bit faster than other start loads(1,028fps vs 800ish), a light crimp in the crimp groove would do nicely.
"...Old manuals didn't even list an OAL for revolver cartridges..." Isn't true. Has nothing whatever to do with plated bullets either. You really only need a crimp for a .357 when using hot loads. Or in a lever action.

[Nick_C_S]

Gaining 150 fps needs about 7.7 grains of HS-6 in that software, and raises the peak pressure just 1500 psi. (I'm curious if that's close to what you wound up with?)

I looked it up this time. I was going off memory last writing. My HS-6 recipe of mention was 8.2 grains (with a CCI 550 mag primer) and yielded 1175 f/s through the 4" 686 (1081 through a 3" 686). At the time of previous writing, the fps I had in my head was 3" data; so that's where I came up with "150 f/s faster." In reality, it was 237 f/s faster. At any rate, it leads slightly less.

Both loadings lead the throats something fierce. The TG round tends to lead througout the barrel, with sightly more buildup near the breech. The HS-6 load clearly is more concentrated at the breech; and migrates downward with continued shooting. Both lead the barrel(s) excessively for my taste.

I've done all the firelapping, etc. I'm officially through loading lead in 357 Mag. And that's okay. Not that big-o-deal.

[KEYBEAR]

In over 50 years of shooting reloads in Rugers (most being 44 Mag) I have never thought about seating a bullet ? Seat in the crimp groove and shoot .
I load tons of cast bullets Crimp is more important to me than overall anything .

[dahermit]

In my limited experience, seating a bullet to the crimp groove and ignoring book OAL is the way to reload for revolvers.

However, there are exceptions. Last week I loaded some .357 Lee 158 R.F, bevel based bullets for a S&W 686 for the first time. I crimped into the crimping groove and found that they came up just short of flush in the chambers. Luckily, I only loaded a few with that O.A.L. The next attempt, I found that I had to crimp past the crimp groove to get them to chamber freely as they should. So in short, one should do a test cartridge or two, and make sure they pass the "plunk test" into the chambers...do not just assume and end up with 100 or more rounds that will not chamber. The bullet has been powder coated with Sky Blue from Powder by the Pound.

[KEYBEAR]

So they came up short ???

So no real problem ??
If they (the bullet) fits it fits ??

[dahermit]

So they came up short ???

So no real problem ??
If they (the bullet) fits it fits ??

"In short...", in that context means, "To sum it up...", not that the cartridge overall length was "short". For those whose first language is not English, is that the crimping groove with some bullets, has to be ignored inasmuch as crimping in the groove will result in a cartridge too long to chamber. If one is still confused, that is why I posted a picture...look carefully at it and you will see that I had to crimp, not in the crimping groove, but closer to the nose of the bullet to get them to chamber in my S&W 686.

[Mike / Tx]

dahermit, this is what I was referring to above about some of the short chambered or shorter cylinder firearms. I guess I have seen it more with the Smith's than anything, but I just recently sent over a handful of different cast bullets to a local fellow to try in his FA 41mag as well. Same issue you referred to.

I agree with the plunk test as well, and although I can't say it doesn't happen with Ruger revolvers, all I have to go on is my one BH in 30 Carbine, my GP-100's and my Redhawks. I have found that some of my DEWC's don't like being seated out in the GP's but other than those, everything else has gone right in without issue.

[Real Gun]

dahermit, That sounds like a case of throats too tight for lead sizes, shearing off lead from hard cast and splattering it all the way down the barrel. You should be able to push a lead bullet through the throats without a lot of force.

The S&W guns are tight as well as having ECM rifling that works better with some hardness lead than others. There isn't a lot of rifling definition, so a hard bullet can maybe just skid down the barrel. I would think a softer bullet would work.

Nick_C_S, Since my load is 10.0 gr of HS-6 (158 gr lead), I was skeptical when reading of a 8.2 and calling it "magnum". I was also skeptical of the velocity cited for that load. To me 8.2 gr would indicate use of softer lead.

[KEYBEAR]

They came up just short of flush in the chambers ?

So the bullet fit right ?? Just short is just that (NOT TO LONG) .
Just so you understand Just Short is OK flush is OK past flush is to long .
Some times people say things that is just really wrong .
Coming up short is just that SHORT not to long .

I think you will be ok once you think about it . (UNDERSTAND)

[dahermit]

They came up just short of flush in the chambers ?

So the bullet fit right ?? Just short is just that (NOT TO LONG) .
Just so you understand Just Short is OK flush is OK past flush is to long .
Some times people say things that is just really wrong .
Coming up short is just that SHORT not to long .

I think you will be ok once you think about it . (UNDERSTAND)

Sigh...

[TimSr]

"...Old manuals didn't even list an OAL for revolver cartridges..." Isn't true.

I only spoke for some I have used. Speer 9, Speer 10, Hodgdon 25th. Lyman 46th was the one of my 4 originals that actually did list OALs.