Shearing off a hair ring of brass during crimp

[greenjoytj]

I am using a Redding 45 Colt bullet seating die, to crimp a bullet cast from 20:1 alloy in a Lyman 452664 four cavity mold in Hornady brass.

I apply maximum crimp with the die body turned down to touch the shell holder.

When I wipe off the bullet to remove lube that has squirted out of the crimp groove up the side of the bullet there is hair thin ring of brass on the paper towel mixed with the lube.

Why am I shearing off brass? Too much crimp?
The finish crimp looks good with the case mouth tucked under the upper edge of the crimp groove to prevent the bullet from being pushed back into the case.

Fired cases still show a slight roll in of residual crimp, which I thought would or should have been ironed out flat parallel to the case wall by the passage of the bullet.

I do use a LEE de-burring tool on the case mouth for a minimalist approach to keep the brass case mouth near original thickness.

[mto7464]

why so much crimp? Back off some just get rid of the flare.

[JimB..]

You sure it’s not lead? Sounds like you might be starting to crimp a little early and catching the driving band.

[ioon44]

From what you described I would agree "Too much crimp"

[redhawk0]

I used to do this on 44 Mag...its too heavy of a crimp. I've also switched to using Lee FCD for my various calibers. It does work much better for crimping. You can crimp as hard as you want without leaving the brass sliver that you're seeing.

redhawk

[Mytmousemalibu]

If you wet tumble, it does peen the case mouth making it a little thicker and that displaced material can shear off as little slivers. Nasty little things!

[greenjoytj]

It’s definitely a brass hair ring I can see the gold colour of the brass.
I do wet tumble with SS pins, but I run my finger tip around the case mouth looking for peening and occasionally find some. It gets removed with the de-burr tool.

I’ll try backing off the amount of crimp I apply with Redding die to 9 o’clock instead of the full 12 o’clock that I have been using.

I have the LEE collet style crimp die, just haven’t got around to trying it yet because I thought it wouldn’t be the best choice to crimp onto the classic sloping crimp groove.

[gnostic]

Just back off the crimp, seating die and see if it stops happening...

[Burnt Fingers]

I've never had to have a crimp die touching the shell holder. Most crimp dies will collapse the case if screwed down that far.

[NSB]

Too much crimp. Too many people add a lot more crimp than is needed to do its job. Pretty much just take the flair off the brass and you're good.

[country gent]

Under pressure the brass cases edge may be shearing off a small bit in the die. This can be increased with pressure, soft brass, sharper corners. or a rough die surface. Another that can affect this is bullet dia neck wall thickness. a bigger bullet may be starting the crimp in the very edge of the crimp area and be in the slight relief cut / corner there, gabbing and pulling a little brass off.

[Iron369]

I get it with 9mm

[Iron369]

Even without any projectiles.

[mdi]

I got the same "hair" when I was reloading some 44 Magnum with heavy loads and an extra heavy roll crimp. Actually the only real "problem" was cleaning up the brass hairs. No difference I could tell in accuracy, pressure indications, etc.. I started using a Lee plain old roll crimp and experienced the brass shaving, but it's not really shaving, its rubbing off a burr. I did two things that eliminated the hairs; first I deburred the case mouth inside and out (not a chamfer, just rounded, took off a few thousandths to "break" the sharp edge.). A bit later I got a Redding Profile crimp die which helped (when I forgot to deburr the case mouths). Works pretty good. I took my crimping a step further recently and got a 44 Magnum collet crimp die from Lee. Excellent tool...

[Bazoo]

I've experienced this before. It is either from too little deburring of the case mouth, or a slightly rough die. RCBS told me I could polish the inside of the die at the crimp ring and it would help as it could be a slight ridge in the die. It can be a combo of both.

Trimming your brass for consistent length will help a lot also.

[Springfield]

Just removing the flare may not be enough for heavy loads in a tube fed lever rifle. Have you ever looked inside a crimping die? Some have just an edge that the brass hits and rolls over, thus scraping off a bit of brass. It doesn't really hurt anything, but I have found my Redding Profile crimp die does a much smoother crimp, especially with my thinner 44-40 brass.

[ShooterAZ]

I am having this very problem right now also, with one die and one caliber. It's with the Redding profile crimp die for the 45 Auto Rim, using brand new Starline brass. I'm waiting to see if it's just a one time thing, or if it's going to keep occurring. If it does keep happening I will contact Redding and see what they say.

[megasupermagnum]

It's just a burr being cut off. The die could be rough, or the brass could have a burr. Either way its no problem. Consider it a free deburring, you normally have a pay extra for that. The collet crimp die is the bees knees though, and won't shave brass.

[Outpost75]

Insufficient outside deburr of the case mouth, combined with excessive crimp.

There is no need whatever for that heavy a crimp, even in a tubular magazine rifle.

Back it off!

[jsizemore]

If he's crimping that early in the seating process then the die is squeezing the brass while the mouth is at the driving band. The brass hasn't even got to the groove yet.