I crimp for my 416 Rigby with a Lee factory crimp die. The crimp rings of two cases came right off when I shot the rifle last week. Must have been blown through the barrel with the bullets. Clearly my crimping weakens the mouth so much so that it separates on the crimp line. What am I doing wrong? Can you over crimp with a Lee factory crimp die?

sounds like work hardened brass.
check the thickness if it been shot a number of times it could have thin neck.
I don't think you can over crimp with a lee crimp die. maybe if its modified

Thanks Hivelosity. But I anneal the cases regularly by applying the flame directly on the neck whilst turning. The cases of which the mouth crimps separated, must have been used three times max.

Can you post a picture of a crimped cartridge with your current set up?

As with anything it can be over done. I would say you over crimped your cases.
when I first started using my FCD I over did it, Not as you did, never lost part of the case.
I might recommend you adjust the FCD so it crimps just the edge of the case mouth, not so much as to have a straight flat area on the neck.
That's what I did, had the flat section of neck.
Leo

If you have your press set to a dead stop or you let it cam over The collet will only close so far/?
Do you trim you brass after each reload ?
If not you could have damaged the mouth of the case by re-crimping in the same crimp.
are you crimps on the cannalure?
Picture is worth a 1000 words. Like the Africa says
I have loaded a lot of 416 weth. mags and never had an issue

Thank you everybody - this is my crimp. I crimp my Rigby loads “upside down” with a Lee FCD for 416 Remington - just add the appropriate spacers!
https://imgur.com/a/h48dZ
https://imgur.com/a/4E99s

You are over crimping, forming a step which weakens the brass. I do not like the Lee factory crimps.
I like a smooth, rounded turned over crimp; not the sharp step like you have. Over crimping is not necessary. They aren't for machine guns.

I had that issue with .458 WM Hornady brass once even on brand new cases.

Never with any other brass.

But I agree you may be crimping a little too hard. With CEB bullets...I like the case mouth to stop just behind a band...then lightly crimp the mouth into the groove with a LFC die.

quote:

You are over crimping,

+1

Making that sharp stepped crimp into a sharp machined groove in those brass bullets is asking for the cartridge brass to be pulled off at the weakened place.

dpcd:

Exactly. Putting "same heavy crimp" to soft bullet body or "round" groove is different story.

I shoot 100's of those CEB brass bullets per year. I crimp them all with a LFC die...albeit in standard fashion.

I try to work all loads with those where I seat the case mouth to the base of a band and then set the die where it just gently rolls over the next band back into that relief groove.

I have .500 NE brass that have been loaded over 10 times and never annealed. No issue.

The same with .458 WM and .375 H&H. Usually only get 10 loading with .458 but forever with .375 brass...both Winchester.

I tried a box of Hornady .458 brass and had this problem on first firing of new brass...with no change to set up.

Went back to WW brass...no issue.

But I agree that those .416 hulls have way too much crimp.

I’ve had some issues with a few Lee FCD’s. Not all. The ones I had issues with we put a very slight taper on them to get rid of the sharp edge on the bottom. Problem solved. Not sure how my machinest buddy did it but he said it was easy.

Thanks once again for all the good advice. Because I crimp upside down I'm going to add another spacer to reduce the crimp surface on the mouth but with the bullet seated as it is right now. I will file the sharp edge off the die (easier from the top) and apply a softer crimp to just gently fold the mouth edge into the groove. Simples!

quote:

Originally posted by adam2:
I crimp for my 416 Rigby with a Lee factory crimp die. What am I doing wrong? Can you over crimp with a Lee factory crimp die?

Hell yes

The LFC die is adjusted by regulating how far you ram up the sleeve at the die bottom. I start by just contacting the sleeve with the shell holder and moving up at 1/4 die turn increments. It doesn't take much to give a tight crimp. Your pics show way too much crimp. You barely want to imprint the brass with the collet fingers.

MOre likely is annealing can be tricky if you guess and by gosh it without the temp paint. Ive never had any problem with the Lee crimp, but if necks get thick I can see where it could be a problem...Check your chamber, might need to inside or outside trim the necks, also check your trim length, lots can go wrong when brass isn't right, especially with big bore brass that tends to be thin in many cases, particularly in double rifle calibers.