Shaving brass when crimping

[johnandersonoutdoors]

Boy do I feel like I have a mystery on my hands. About two weeks ago I started experiencing little brass shavings that are super thin that are coming from the outside of the case mouth during the crimping step.

Over the last year I have loaded 2500 rounds of 9mm without any problems and I have been quite meticulous and these shavings just started two weeks ago. I don't get it.

I have been loading on a Redding single stage with Dillon 9mm dies. I measure all my cases and they all fall between .750 and .754. So I have my dies setup to work well with cases of that length. Over time I have played with shorter oals like 1.125 all the way up to 1.150. I am using Montana Gold 115 gr FMJ. I set the crimp to bring finished case mouth dimensions to around .376 to .378.

Like I said, 2500 rounds later after never experiencing a single problem and all of a sudden I am getting these shavings when I crimp.

It just doesn't make sense. I am not belling more than I used to. I am not crimping more than I used to. The only thing that changed in the last couple of weeks is I went from using Hornady bushing kit to easily swap my dies to a regular lock ring now. Also I increased oal to longest ever 1.160 (which actually is my most accurate ammo so far in my M&P9).

So 2500 rounds of great ammo with no shavings, then I switch die locking system and play with oal and now getting shaving like mad from the outside of the case mouth on crimping step. It literally looks like the mouth gets chamfered.

 

[Mohave-Tec]

It's not when you crimp, it just seams like it.
If you are using a Lee Classic Turret press, you've raised die height under the auto charger so the case mouth is no longer belling to accept the bullet during seating. Your case mouth is shaving copper off the side of your bullet.
I hope I've used the correct terminology.

 

[gamestalker]

Actually this is an on and off issue I see withal handgun cartridges, and I load on a single stage, and only load jacketed bullets. I use a Lee 9mm die set, RCBS .357, Lee 10mm, RCBS 44mag.,. I did't see it all the time, just now and then over the last 30 -ish years. At first I thought it was related to my crimp, but then I quit crimping all my AL rimless brass and it still shows up. For the most part it hasn't caused me to worry, so I've not done much to diagnose the cause.

But not too long ago, probably a year or so, I decided to find the culprit. So what I did to better make this determination, is the very next time it happened, I took the plug out and I polished the sharp edge off, cause that was the only part I could see had any evidence of jacket shavings on it, it stopped instantly, and it never happened again on that seating die. Next time it was with .357, same thing, polished it, and it never happened again. The edge of those seating plugs is sometimes really sharp on many of them, and they won't shave every single bullet, only one's that have the right, or wrong profile as it were, that allows it to slightly slide over the bullet at the point when resistance it the highest, sometimes that is during a crimp, sometimes just a tight fitting bullet neck tension. The fact that I was encountering it when I wasn't using any crimp at all, is what lead me to the plug as the culprit. Although, I noticed it was more common during crimping, which makes sense, as that is when there can be more resistance against the plug to bullet olgive.

GS

 

[Walkalong]

Deburr and chamfer the cases, and it will probably stop. If not, look to die adjustment. That said, once it does it on a case, it usually doesn't do it again, assuming the dies are set up OK.

 

[johnandersonoutdoors]

gamestalker,

I will take a look at seating stem again and maybe mess with it, but I am very sure it is happening during crimp. I am building dummy rounds one at a time and literally seeing it happen.


Walkalong,

This is just weird. It is used brass that has previously been fired. The brass didn't do this the first time it was reloaded.

As I said in my original post, nothing has changed other than my die locking system and I am loading slightly longer oal than I ever had before.

I have tried scrubbing out the crimping dies but there wasn't really anything in there anyway to cause a problem.

 

[Blue68f100]

Deburr the brass was my first thought if new brass. But since these have been reloaded before the burrs are normally worked off.

Since the die is locked down now and not allowed to float your alignment may be off slightly. Lock the die in place when the ram is full up with a cartridge in place. See if that helps.

 

[GLOOB]

My 380 seat/crimp die does that, frequently. In addition to shavings, you can see some scratches on the case mouth. Sometimes, there's even a little sticking, then a crunch as the brass goes in. I have never loaded enough 380 to care, but I suspect the flared opening on the crimping ring part of the die is too small. So some of the brass gets caught on the edge before it finally slips through. If this is bothering you, you might take the die apart and see if you can't clean up that leading edge of the crimping ring.

 

[Walkalong]

I have had Lee expanders do it, until I polished them.

 

[Otto]

Check that your seating die is adjusted not to crimp while seating. Increase your bell.
If you're shaving FMJ bullets it's nearly always a die adjustment issue.

 

[rondog]

I see it too, but it's my Lee powder-through expander plugs doing it. They're intentionally made with a rough surface, when belling the case mouths it acts like a tiny file and deburrs the case mouths just a skosh before they hit the belling flare on the plug.

The rough surface also grabs the case and creates just a little friction, when pulling the ram back down after the powder dump this friction imparts a slight jarring action which helps to shake out the last bit of powder.

I found that all annoying when I first got my LCT setup, so I called Lee and asked what was wrong. They explained it was rough by design and told me all the above info. So I don't worry about the tiny shavings, I'll just clean them out periodically with a little brush.

 

[moxie]

It happens, especially with extra heavy crimp. Try backing it off a bit.

 

[gamestalker]

I don't know, I don't crimp rimless cartridges at all. I chamfer every single piece of brass too, yet it continued to happen off and on until I smoothed out the edge of the seating stems. There is apparently very likely more than one cause. I know I've seen it happen when nothing else could be causing it but the seating stem, being case mouth was nicely chamfered, and I wasn't crimping at all, soo? And I've pulled bullets to see if anything came off the bearing surface, and it was without evidence of shaving.

A mystery indeed.

GS

 

[GLOOB]

+1. This most certainly can happen with a Lee seating die. It's not shavings off the bullet. It's not using too much crimp. Either the crimp ring or maybe even the die body, itself, can catch and scratch the brass. No, this is not normal, but yes, it can happen if you get a bad die.

 

[Fatelvis]

This is the reason I always seat and crimp in separate steps now. If you have a slight bell in your case mouths at seating, it will definitely eliminate the shavings.

 

[Jaxondog]

What I believe is happening is you are belling the case a little too much. Then when you seat the bullet the edge of the case is scraping the inside of the die causing what probably looks like gold dust to appear under and around your shell holder. How am I doing so far?

 

[murf]

suggest you clean your die.

murf