A .357 Mag headache

C

cdoc42

New member
I can’t say that I ever paid any attention to case size in handguns, especially revolvers. I’ve been shooting a Ruger GP-100 .38/.357 for at least 25 years now, but not really as often as my other calibers. I have not had any problems with target shooting using 17.0gr of 2400 (Lyman max 17.7gr) with either a Remington or Winchester 125gr JHP seated to a COL of 1.590.”
For whatever reason, I can’t explain, I decided to double-check the recommended COL and now I really opened a can of worms.

The 5th Ed of Lyman uses a Hornady 125gr JHP, and lists the COL at 1.590.” Fine. I should have quit at that point, but I happened to see their “trim to” measurement being 1.285”.

My Hodgdon manual says the .357 case shoud be 1.290” max; “trim” 1.285” (I assume, trim TO). They use the Hornady 125gr XTP and their COL is also 1.590.”

The Hornady manual says to max case length is 1.290”, but the trim to length is 1.280.”
No matter what weight bullet they list, the COL is always 1.590.”

The Speer Manual also lists 1.290 as max and 1.280 as trim to. But their COL listing is 1.575” for the 125gr JSP, JHP and TMJ styles, and 1.580” for the GD-HP bullet.

Speer lists 1.590” for their 140gr bullet, but for their 158gr bullet their COL is 1.570” for the JSP, JHP and TMJ, and 1.575” for the GD-HP.

I don’t have any COL data for the bullet I currently use – the Winchester 125gr JHP. I assume since I haven’t injured or killed myself, 1.590” is satisfactory.

But getting the cartridge COL to an exact 1.590” is another story. I decided to make a dummy with the case measuring in the middle (1.285”) of the max 1.290” and trim to 1.280.” I belled the mouth just enough to accept the bullet to be seated, and seated it to 1.590.”

All the remaining cases are somewhere between 1.280” and 1.290,” what appears to be an acceptable spread. But the bell for any case less than 1.285” is a bit tighter, while the bell for those beyond 1.285 is larger. As a result, if I seat and crimp simultaneously, I cannot get a consistent COL of 1.590.” The problem most often is with the cases approaching 1.290” – the bell is large, and I think the crimp starts to engage before the bullet is fully seated. So I usually find the COL to be 1.594” or 1.596.” The opposite occurs with the smaller cases and often the COL is 1.588 or less.

I think I can solve it by seating first, then crimping, but do I really have to use an extra step or is the seated COL of 1.588” to 1.594” (or so) any problem?

Now, one may suggest trimming all cases to the same size to start. Here's the problem. If I trim to 1.280" and set the dies to bell, seat and crimp at that size, I've found the cases grow as much as 0.006" after resizing the fired case, so I'd have a bunch that measure 1.286," and ALL would require trimming again.
 
Too wordy for me. Here’s what matters....your cases get longer when you size them. Size first, then trim. Also, it’s very rare to have to trim straight walled pistol cases like the .38/.357. When it’s all said and done, if the bullet doesn’t stick out and prevent the cylinder from turning, it really doesn’t matter what the cartridge overall length is. You’re really over thinking this. Revolvers just aren’t that critical. I’ve owned several custom built revolvers over the years that were superbly accurate (two by Bill Davis) and didn’t spend that much effort into thinking about it. Both of those guns would shoot five shots into one inch at 50 yards with full power loads.
 
I only halfway read all that; will go back and read it again, but my first thought is you just need to sort the brass by headstamp. (or by length) Then don't worry about it. Bell the cases just enough to get the bullet started -- you're doing that. The neck tension should be almost enough to keep the bullets from jumping. In a long case like .357, I don't think 5 thousandths is going to be significant unless you are making proof loads. And of course you're not making overloads like that.

If you get better ammo by crimping as a separate step, it might be worth it. The bullets I use all have deep cannelures and I crimp to that in one step. If I were loading jacketed bullets I can see crimping those as an extra step so the bullet is not moving as it's being crimped.
 
Yeah, that was wordy; but I did read it all. You are a seasoned loader and deserve all due respect. But I think you might have gotten yourself all wrapped around the axle and are in need of a complete re-approach for 357 Magnum.

I'm a revolver guy. I have loaded - by far - more 38 Special and 357 Magnum than any other cartridges. I have been loading them since 1984.

First thing is first: if your bullet is cannelured - and I believe that every bullet you mentioned is - ignore OAL measurements. Seat to the cannelure - period. I do not know the OAL of any of my 357 Magnum ammunition. Their OAL is "to the cannelure":p. Taking this first step will clear up at least half your confusion.

Now the brass: I do recommend sorting by headstamp; but it may not be entirely necessary. I have R-P (Remington) brass (which I craft ammo for use in my Henry rifle); and Starline brass (which I craft ammo for use in my revolvers). I also have "other" brass that I consider mixed; but I don't load with it at this time. Side note: My R-P and Starline brass are both NON-nickel plated - but that's for another thread.

Trimming: I tryed to avoid it for years, but you really need to trim your 357 Mag brass if you want to actually make good ammo. Regardless of headstamp, I trim my brass now. After shooting, I resize, flair, then measure. If it is <1.283", I toss it in the bin for reloading. If it is >/= 1.283", I toss it in the bin for trimming. I trim to 1.280" (with some inevitable variance - rarely exceeding .002"). I usually wait for a bunch to need trimming, then do them all at once - tends to be a winter time project. Don't fixate on the manual's trim length - focus on your trim length - whatever you choose to make it. I did 1.280. Many do 1.275. Others may do something else. The manuals tell you their trim length just so you know - it doesn't mean you have to use theirs.

So in short: Trim your brass for consistency; then seat to the cannelure . . . DONE.
 
KISS principle applies here. Take the longest case, seat it so very little of the cannelure/crimp groove is exposed without crimping simultaneously. Then crimp separately with a Lee collet crimp die, they are much more tolerant of varying case lengths.
 
Yeah you’re getting wrapped around the axle over nothing. You don’t want to be far under minimum overall length because of pressure increases. Other than that, if it fits in the mag and/or doesn’t stick out the cylinder you are good. Well you want to have some consistency, but I typically haven’t worried about anything greater than a .006 OAL variance. Even if there’s an extreme spread of .010 I usually roll with it, but inspect to see what’s happening for next time.
 
Trim? Who trims straight walled cases?
Click to expand...

I do. I didn't want to. But I had to. Over time, my 357 and 44 Mag case lengths were running all over the place. Crimps were becoming very inconsistent. The cases stretch.

Sticking with 357 Magnum, when I first started trimming, many cases were way over spec (1.290"). I had quite a few over 1.300." So now I trim after sizing and flairing. Typically, about one in four or five need to taken out of the reloading pipeline for trimming. I wait 'till I've collected up about 40 or so, and trim to 1.280 (as already mentioned).

BTW, it doesn't seem to be much of an issue with 38 or 44 Special - I don't trim. I guess the pressures aren't high enough to stretch the cases to any degree. Also, the propellants used in 38/44 Spl are typically faster and thus, crimps aren't nearly as critical. And in my case (no pun intended), many of my 38/44 Spl loadings are with a taper crimp. Case length isn't nearly as critical when a taper crimp is applied.
 
Trim? Who trims straight walled cases?
Click to expand...
Straight wall cases are the reason I purchased my trimmer. I had a batch of cases that had a good crimp all the way into the canelure on one side and barely any case in the canelure on the other side. Very inconsistent. I am much happier now.

I trim my cases in batches. I load them in the same batches. That way I set my crimp and length to that batch.
 
As said above, you are overthinking this. Just crimp in the crimp groove (what it is there for) and your done. Over all the years (since '80 or so) I reloaded, I've not paid any attention to OAL except in .45 ACP.

Also, never trimmed a case either. The brass I mostly use is Starline and crimping has never been a problem.
 
Thanks to all respondents. Those who commented on the depth of my adventure hit the nail right on the head. It truly was one of those things that began to spin out of control untilI felt like I was in the woods, walking in circles. Climbing a tree, I saw The Firing Line and I knew that would provide a way out. And it did!

I will watch for those cases that exceed 1.290" because the crimps will be tighter, maybe a pressure issue, but even at that, I've been shooting these things all these years and I never had a problem, which brought me right back to the question, "Why the hell did I get into this in the first place?"

BUT - I'm glad I did, because look at all the valuable information you reloaders supplied!

Thanks again, and good shooting!
 
Sorry, trimmer guys; but I have NEVER trimmed a 38 or 357 case in over 35 years; and I am still reloading some of those cases.
 
In most cases, having to trim any pistol/revolver case would be highly unusual. After 25 years, that'd still be the case. Pistol and revolver cases rarely if ever stretch.
And you only need a crimp for hot loads or ammo used in a lever action. Alliant's current Max for 2400 is 17.5. Close enough. No pressures given by them.
"...when I first started trimming..." Range brass that may have been fired out of a rifle? Case stretching just normally doesn't happen.
SAAMI spec Max case length for the .357 Mag is 1.290 -.020". That means Max case length is 1.290" with a 20 thou less tolerance. Max COAL is 1.590". Minimum is 1.405". Anything in between those is fine. Regardless of the bullet weight or its shape.
"..."Why the hell did I get into this in the first place?"..." I'd bet somebody told you you'd save a pile of money by reloading.
 
"..."Why the hell did I get into this in the first place?"..." I'd bet somebody told you you'd save a pile of money by reloading."

T.O'heir, you would have lost your bet because you must have missed some or most of my 922 posts on this format since 2005. I haven't purchased a factory round since 1976 when I first started reloading.

I also challenge the experience that, at least, .357 cass do not stretch. In my discussion as OP I mentioned I measured a fired case at 1.280 and when I resized it, it grew to as much as 1.286. Those that measured 1.286 grew to 1.292. So no matter what the numbers are, they definitely grow.
 
I also challenge the experience that, at least, .357 cases do not stretch. In my discussion as OP I mentioned I measured a fired case at 1.280 and when I resized it, it grew to as much as 1.286. Those that measured 1.286 grew to 1.292. So no matter what the numbers are, they definitely grow.
Click to expand...

That has been my experience too. 357 Magnum cases most definitely stretch.
 
If your resized case is X length, then loaded and fired and shrinks to Y length but upon resizing it returns to X length then it has not stretched. So just comparing the change in length between unsized and resized brass isn’t a valid comparison. The only valid comparison is if the same case after being fired and resized is then stretched to a longer length than the last time it was resized.
 
Some of you seem to understand what’s happening when you size a case, and some of you don’t. When the cartridge is fired, the diameter of the case expands as it is forced out to meet the chamber walls. At this point, it gets shorter in length simply because it doesn’t increase in mass so the material has to come from some where. When removed from the chamber it has the same mass, but it’s been shifted from the length to the diameter...it’s pliable. When you size it, you force the material to go somewhere, and it goes from diameter to length. If you want to call that “getting longer” I guess you can call it that, but you need to understand what’s happening. I’ve been shooting straight wall pistol cases for over fifty years. Loaders who shoot and load a LOT usually understand this. If you want to measure case length, start with sized cases, shoot them and resize them, and then measure again. Some lots of brass will be slightly different lengths than other lots (or brands). If they all fit in the cannelure of the bullet there’s nothing to worry about. Will it effect bullet crimp if there are slight differences.....yes it can. If they all fit reasonably well into the cannelure you’d be very hard pressed to be able to measure the effect on accuracy. The real problem with case stretch comes into play with bottle neck cases. Moving material from the case body to the neck definitely causes problems. That’s a whole different ball game.
 
The last two posts make all the sense in the world. I will definitely check things out as jetinteriorguy described.

Am I correct in assuming those of you who advocate no need to trim are ok with any position of the case within the size of the cannelure? What are your thoughts on the depth of the bullet seat when the case crimps outside of the longest size of the cannelure? Any pressure concerns?
 
It might be useful to trim once, but I think you can accomplish the same thing just by sorting by headstamps. I trim rifle cases, including .30 Carbine. (especially .30 Carbine) I don't trim pistol cartridges just because I've never found a need to. About 98% of the time I use cast bullets, so it doesn't matter if the bullet is still moving slightly as the crimp die is doing its thing. For jacketed bullets it might make a difference, but it wont be a big difference.

One thing to watch out for is overcrimping because some of the cases are long. The problem there is it reduces the case life.
 
I only trim my straight wall brass to make all of the cases the same length and to square up the case mouth. It is not that much effort, and it makes me happy. If you are happy doing it your way, more power to ya. No single right way to do this stuff, but there are a few wrong ways. If it works for you and is safe, it all good.
 
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