Inconsistent crimp and COL for .357 Magnum

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I finally determined a proper load for my .357 Magnum with Sierra 125 gr bullet and AA#9 powder.

Now, I'm have trouble with getting a consistent crimp and COL.

I am using the Lee 3-die carbide .38 Special/.357 Magnum set in a single stage press. Per instructions, I set the COL first, back out the seater plug and screw in the die until it touches the brass shoulder, add 1/8 turn for the crimp, and reset the seater plug to get the previously determined COL. Everything looks good. I start to go through my prepared cases and I'm seeing very inconsistent results. Some bullets are seated too high and some too low. The variance is over +/-0.030" Most of the crimps are weak and I can push the bullet easily into the case. As I go through my prepared cases, I've tried screwing the die in to add more crimp, but the cases get deformed or the bullets get set too high. I've never experienced this before.

I'm thinking that maybe the wide, soft lead tip of the bullet is getting positioned differently in each case because the seater plug end is concave? Is there a flat end version of the seater plug?

Or, is the brass overworked and weak? Too many reloads?

Did I over-expand the case mouths? I took 5 cases and resize them, and did a minimal neck expansion, but it didn't seem to help.

I'm really at a loss as to the issue.

Thanks.
 
have you examined your cases for consistent length? Measured those bullets for proper diameter? dunno what else to suggest, but if you find that the cases are being expanded too far, you might be able to expand them with a .355 expander plug.

By all means investigate crimping/seating in two separate steps. Seat the bullets to proper depth. Remove seater, crimp by feel. You will get proper oal and proper crimp in two steps, but still, your brass will have to be the proper length and consistent.

Maybe that will be some help.
 
You should not be able to "push the bullet easily into the case" after resizing regardless of crimp. Maybe try some cases that aren't worn out.
If your cases are trimmed to uniform length, I'm not so sure that "add 1/8 turn for the crimp," is adequate. On heavy load revolver cartridges, I roll crimp to a visual satisfaction level rather than a specific "turn it this much" measurement.
 
...add 1/8 turn for the crimp,...
Click to expand...
There's your problem. Add at least ½ (up to ⅔) turn for the proper crimp.
Try it and let us know.... ;)


postscript: While you're at it, make sure your initial COL puts the case mouth
nearly at the very top of the crimp groove. That way crimping inwards
doesn't start until the case mouth is at/past the start of the cannelure and
doesn't grab the bullet too early while it's still being shoved into the case.
 
While inconsistent crimp can come from inconsistent case length, it would not affect OAL....sounds like you have more than one thing going on. I agree with you about the seating plug stem not matching the bullet profile contributing to the inconsistent OALs. Too much flare can result in loose neck tension, while a roll crimp into the cannelure does help hold the bullet in the case, proper neck tension should keep the bullet from moving easily in the case without the crimp. Some folks use hot glue to make the proper profile in their seating stem, one can have Lee make a custom one. RCBS includes two stems with their seating dies. On handgun bullets, for the most part, a small deformation of the nose profile will not affect accuracy.

I'd try less flare, more crimp and maybe seating and crimping in two steps. If you still have problems with neck tension, it may be a problem with your sizing die.
 
Separate crimping from seating. Getting a crimp on a moving bullet can be tough for a mew reloader as the adjustment has to be "just so". Back off the crimping function of the die and adjust the bullet depth (seat to the cannalure/crimp groove and don't worry about book OAL). After you've seated all the bullets (you could measure the OAL now as a "test" of your seating function) back off the seating stem, and adjust the crimp and crimp all the cartridges. Measure. The OAL and crimp will probably be much more consistent...;)

FWIW; been reloading 38 Specials and .357 Magnums for over 30 years and keeping case length exactly the same is much overrated. If your cases are all within .010" there won't be enough variation in the crimp to make any noticeable difference in accuracy, combustion or function. Perhaps in deep reloading theory, but in real life, nope. I don't remember the last time I measured a 38/357 case, mebbe 1980?...
 
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"...Too many reloads?..." Case mouths would be cracking.
Unless the dies are not tight and seater plug not locked, it's far more likely to be inconsistent operation of the ram.
"...can push the bullet easily..." Indicates insufficient crimp. However, it may or may not be a '1/8" turn' thing. Crimping is more of an art than a science. The correct amount is 'enough'. That being just enough to hold the bullet in place under recoil and no more. Even on a rip snorting load.
"...I don't remember..." Ditto. And it's not age related. snicker. Even hot loaded .357 cases don't stretch much, if at all.
 
Well, I measured about 10 cases and most were between 1.580" and 1.582". A few were around 1.576" However, I didn't trim them because they are all below the trim to length of 1.585".

The bullets are all 0.357" +/- 0.0005".

I did some 158 gr bullets with newer cases on this same setup a few weeks ago and I had no issues. So, I'm thinking the cases are worn out.

I've read that I shouldn't be able to push the bullets in even before crimping. The crimp just adds some insurance against movement. This sounds correct to me from past experience. I don't have any unused cases at the moment to try.

I'm thinking of trashing the cases and primers and saving the powder and bullets using my collet puller.

Does this make sense?
 
I have a set of 44mag RCBS dies, had a round seating die trying to seat SWC. Would seat the bullets crooked /inconsistent often. Called RCBS, they sent me two different seating stems. One was a flat point seater for SWC, made all the difference in the world. So to answer the question yes I think it would do you well.
 
I did some 158 gr bullets with newer cases on this same setup a few weeks ago and I had no issues. So, I'm thinking the cases are worn out.
Click to expand...
Nope, cases won't "wear out". 99% will split when they get "old". (I have 38 Special brass that has been reloaded 20-25 times, and some 357 Magnum brass reloaded at least 15 times).

When you separate crimping from seating, try/test bullet fit, neck tension; seat bullet, don't crimp, and check...
 
I've read that I shouldn't be able to push the bullets in even before crimping. The crimp just adds some insurance against movement.
Click to expand...
Very true. The grip the case puts on the bullet when you seat it is bullet tension, aka neck tension, and it's critical for magnum rounds. The roll crimp provides extra insurance against the bullet pulling out of the case.

If you're loading AA#9 I'm guessing these are full power loads and attention to detail becomes more important.

For full power magnum loads I keep a batch of brass separate from the rest.

Trim all cases to a uniform length even if it's a little less than the trim to length. For my magnum batch I trimmed them all just once, they stay pretty consistent after that.

Expand to a bare minimum (my cases measure .377" after expansion/flare). A nice upgrade is the Lyman 'M' expander. I don't like loading revolver ammo without one.

Crimp magnum rounds so that the case mouth just crushes into the little ribs in the crimp groove on the bullet. Go slow, don't judge or adjust by half turns or any other coarse measurements.
 
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1. If you have a FP bullet, you might try a flat top seater plug. (Not sure what comes with the Lee 3 die set.) I have my 3 .38 Spec RCBS dies in a Dillon die head, and I load a lot of 125 JHPs and FPs. Looks like I have a flat seater plug in there. I only use the round nose plug when (occasionally) loading RN bullets.

2. Inconsistent seating depth is one thing, lack of neck tension is another. I suppose lack of neck tension MIGHT contribute to the former. As stated, lack of neck tension may be caused by expander die and/or plug seated too far down and too much belling of the case mouth, opening the case up too wide and undoing the re-sizing. Once in a while in some calibers, you will get an expander plug that is to large and you need to get (or make) a smaller diameter plug. I am hoping / expecting that would not be the cause here.

3. Is your seating plug stem tight? I have had everything set up perfectly, and forgot to check that the stem is tight, and gotten erratic depths.

4. I seat and roll crimp in the same step for .38 Spec (only 3 stations in the die head). As such, at least with my RCBS die set, seating and crimping in the same step gets me good quality loads. However I concur that seating and crimping in separate steps can improve quality.

5. How old is your brass, how many loads? This typically would not be an issue, and is therefore low on my list, but would be good to know how many loads you have.

6. I too have loaded .38 Spec for many years, and not measured a case length nor trimmed in a long time, have not had a problem being sufficiently within the cannelure on crimps. I don't think trimming solves your problem, but opinions and experienced mileage may vary.

7. Finally, I echo the go slow and be deliberate advice. Setting up 3 die sets in these situations should be easy and routine, but sometimes it takes a little effort, persistence to get it right.
 
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Okay, I took 10 cases again and went through the entire process while measuring each step.

After resizing, the inside case mouths were 0.350".

I took apart the expander die and found the expander die plug diameter was 0.357" and 0.358" (must not be exactly round!). The Lee die has a floating expander plug.

After the expander die, I measured the very end of the cases and found them to be between 0.357" and 0.359". The bullets easily were pushed and pulled in the case all the way to the cannelure and beyond.

I tried reseating the bullets without any crimp and got inconsistent lengths, but I guess this expected since they move so easily.

So, should I be able to move the bullets without crimp? Is there not enough neck tension?

I might have to invest in the RCBS which comes with 2 seater plugs one of which is a flat seater plug which would prevent the bullets from going in skewed. Or, a Hornady which claims to have a alignment mechanism in the seater die that aligns the bullets as they enter.

Go for a separate crimp only die?
 
Your first problem is that expander plug. It's too big to ever get good neck tension.

Knowing what you've gone through already, I'd cut to the the chase and just get the (carbide) RCBS set. It's got the right expander, the right seater/crimp combo, and you don't have to lube the cases. ;)
 
I've read that I shouldn't be able to push the bullets in even before crimping. The crimp just adds some insurance against movement.
Click to expand...

...as I said in my first post,

proper neck tension should keep the bullet from moving easily in the case without the crimp
Click to expand...

Thus if you are not over expanding the cases, and your sizing die is properly made, the only reason you need to crimp is to take the flare outta the case mouth. This is all folks do when reloading for pistols. Pistol bullets don't have a cannelure. Revolvers use a cannelured bullet to help prevent bullet jump under recoil. Very few plated bullets used in revolvers have a cannelure because they are used in applications where recoil is light and bullet jump is a moot point.

You should be flaring/belling the mouth of the case only enough to accept the very back of the bullet used. You do not expand the case for the whole length of the bullet. The bullet once started will stretch the case around itself, making for neck tension. If you can start a bullet into the case without any flare/bell, you either have a bad sizing die or undersized bullets. If you cannot start a bullet before expanding and then can push the bullet easily completely to the cannleure by hand after flaring/belling, you are over flaring/belling, or have a bad flaring die. Lighter bullets are more likely to display insufficient neck tension because they generally do not seat as deep into the case as heavier bullets, i.e. 125gr bullets are more likely to display insufficient neck tension than the 158 gr when either a bad die or incorrect technique is used. I had to buy a undersized sizing die from Lee for reloading .380 because their stock sizing die did not properly resize my cases resulting in insufficient neck tension. I tough I was saving money over buying a set of RCBS dies, but after paying out $30 for the undersized sizing die, it would have been cheaper to go with the RCBS in the first place.

As for handgun brass wearing out, as mikld said, most of the time the mouths will crack/split when they get old from being worked(belling and crimping). But they can also get hard and less pliable which can result in poor neck tension. New brass, properly annealed will "spring back", while older brass hardened from shooting and working will not. This is more noticeable from high pressure rounds like full house magnum loadings. Annealing used brass, while a common practice when reloading for rifle, is seldom done by those handloading for handgun.
 
If your brass measures .357" after the expanding operation, and if you're handy in a workshop, just some emery cloth or a fine file to reduce the diameter of the stem to .354" or so. I'd chuck the stem in my drill and spin the stem while I removed a bit of metal...
 
reddog81: The bullets are 0.357". They are 38 caliber for sure. Not 9mm.

buck460XVR: I agree. I think the neck tension is not enough. I might go for the RCBS set. My Lee set is carbide and I've had good luck with it. But, I've only done 158 gr bullets in the past.

mikld: I do have a mini-lathe and can turn down the expander plug. It should be 0.354"? Is that enough to start a 0.357" diameter bullet?

Do I need a separate crimping die? Or, stay with a crimp/seating die?
 
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