Expander mandrel problem... anyone experienced this before?

[copperking81]

Wondering if anyone else has encountered this problem and can shed some light.

I ditched the expander balls in my Redding dies a ways back and for the neck expaning operation, I use a Sinclair carbide expander mandrel. I also use their die body. I've used this method on thousands of rounds on probably a half dozen different calibers and no issues to date. Only positive results in minimizing run out.

Well, I just started reloading for a .300 WSM and encountered an issue while using the same technique. The attached picture doesn't show it well but at the base of the shoulder the brass has been pushed slightly outward...like the shoulder got pinched / pushed down during the expanding operation.

It clearly didn't happen during FL resizing since I can't even get any of the affected cases back in the FL sizing die now. My first thought was that the shoulder or tip of the neck was bottoming out in the die body but I don't see any evidence of that. I painted up the neck and shoulder with a sharpie and I don't see any marks in the die body. Doesn't look like its going in deep enough either. Only thing I can come up with is that the friction when the mandrel goes in is great enough that the brass is getting pushed down and overflowing over the sides of the case body.

Attached are pics of the brass, the expander mandrel, and the die body.

 

[Sundown]

Did you reset the mandrel die to the new case? Is the case bottoming out on the mandrel die body?

 

[retired]

yep i bet he hit the end of mandrel.

Did you reset the mandrel die to the new case? Is the case bottoming out on the mandrel die body?

 

[Steve morgan]

Wondering if anyone else has encountered this problem and can shed some light.

I ditched the expander balls in my Redding dies a ways back and for the neck expaning operation, I use a Sinclair carbide expander mandrel. I also use their die body. I've used this method on thousands of rounds on probably a half dozen different calibers and no issues to date. Only positive results in minimizing run out.

Well, I just started reloading for a .300 WSM and encountered an issue while using the same technique. The attached picture doesn't show it well but at the base of the shoulder the brass has been pushed slightly outward...like the shoulder got pinched / pushed down during the expanding operation.

It clearly didn't happen during FL resizing since I can't even get any of the affected cases back in the FL sizing die now. My first thought was that the shoulder or tip of the neck was bottoming out in the die body but I don't see any evidence of that. I painted up the neck and shoulder with a sharpie and I don't see any marks in the die body. Doesn't look like its going in deep enough either. Only thing I can come up with is that the friction when the mandrel goes in is great enough that the brass is getting pushed down and overflowing over the sides of the case body.

Attached are pics of the brass, the expander mandrel, and the die body.

View attachment 1047586

View attachment 1047587 View attachment 1047588

Case mouth is probably hitting shoulder on mandrill

 

[copperking81]

I don't think it's bottoming out. I'm using a Co-Ax press and can see how much of the case is showing at the bottom of the die when the case is fully in the die body with the press in full battery. There is plenty of brass showing. If I pull the die and case off the press and insert it by hand, bottoming it out, there is significantly less brass showing at the base of the case.

I also tried marking up the neck with a sharpie, running it through the die body, and then checking for black marks in the die body. No marks at all...

 

[copperking81]

Unfortunately, I don't have brass on hand to try and recreate the condition while observing. I'll get more later and look for it but hoping to trace down root cause before hand...

 

[Toejoe12]

If it's not bottoming out then the next question is how much is your FL die sizing the neck down? Next.....what is the mandrel size? If you felt a lot of resistance and/or you're expanding back up over .0025 or .003 you could be crushing the shoulder a tad if you're annealing and the necks and shoulders are softer. Lastly, make sure you have the correct caliber mandrel in the die.......I've been there done that

 

[Dusty Stevens]

Too tight or not enough lube. Get a smaller dia mandrel. Porter precision products makes one that takes any size instead of using a universal turning mandrel.

 

[copperking81]

I have mandrels for every caliber I load. The .30 cal mandrel, which is what I used for this, is the biggest I've got so can't be the wrong mandrel (all others are too small). It sizes .002 under bullet diameter. It's carbide which they say doesn't require lube, and I haven't ever used it, but I'm betting that's the problem in this case.

Its Nosler brass... if that has any bearing on the matter.

The carbide mandrels ain't cheap but I was willing to spend the 5X asking price, over the steel variety which do require lube, just so I don't have to lube. Its going to suck if I still have to for this cartridge.

 

[Dusty Stevens]

You need to lube it. Its a turning mandrel- when turning carbide doesnt need lube they say but if youre expanding your neck with no lube we just identified the issue.

 

[WillyTP]

I have mandrels for every caliber I load. The .30 cal mandrel, which is what I used for this, is the biggest I've got so can't be the wrong mandrel (all others are too small). It sizes .002 under bullet diameter. It's carbide which they say doesn't require lube, and I haven't ever used it, but I'm betting that's the problem in this case.

Its Nosler brass... if that has any bearing on the matter.

The carbide mandrels ain't cheap but I was willing to spend the 5X asking price, over the steel variety which do require lube, just so I don't have to lube. Its going to suck if I still have to for this cartridge.

Just curious but why is lube such a problem? When expanding new 6mm brass to 30 cal I’ve yet to encounter the brass collapsing like that. I have split some necks when I get too fast with the press handle.

 

[copperking81]

Yep, I think its the lube (or lack of). I have to say though, that I've reloaded several thousand rounds (.204, .220, .243, .270, and 30-06), never lubed and never had an issue. Concentricity always improved so I guess I didn't harm the brass... or could I have? If not, have I just been lucky?

And no, not that big of a deal to lube. Its just one more step I have to try and remember

 

[TikkaSporter]

Only time I ever made a case look like that with an expander mandrel, it was pushing the mandrel through a donut with out enough lube. Inside neck reamer and better lube routine solved the issue.

 

[ireload2]

Your case mouth is hitting something.
That is the same kind of defect you get when seating bullets and the case mouth hits the crimping shoulder too hard.

 

[R.Morehouse]

Curious....What brand of brass is it?