Overexpansion of neck on a Mauser 7x57

[Homerange]

Ah, not enough then. Been there done that too and gave away grease types lubes and went to powdered graphite mixed in fine lead shot that you plunge the case into and then pop the case into the die.
It takes a couple of sizing's to fully coat the die and then you're away if you don't mind the bit of a mess graphite makes. I don't as it's cheap and a little goes a long way.

Most of the sizing is happening at the shoulder/neck area so this must be properly lubed for minimal effort.

 

[Uncle Ed]

You are actually kidding me .... I just thought about it again and not just put a little bit of the Lee Resizing Lube on the case .. but lots ... and guess what ....
EVERYONE was right .... the lube IS the issue.

I didn't know that Ewoks reloaded, just remember if the case screams in pain add more lube.

 

[Pops70]

Ah, not enough then. Been there done that too and gave away grease types lubes and went to powdered graphite mixed in fine lead shot that you plunge the case into and then pop the case into the die.
It takes a couple of sizing's to fully coat the die and then you're away if you don't mind the bit of a mess graphite makes. I don't as it's cheap and a little goes a long way.

Most of the sizing is happening at the shoulder/neck area so this must be properly lubed for minimal effort.

I tried different amounts of lube just now and yes, more is better with the cases I have.
I'll just have to bite the bullet and spend a little more on that side ... stuck cases are not fun.
The 303's size easily with the one shot ... but the large 7x57 only with the paste lube.

Thanks everyone for the input.
One issue solved .... but still going to make a chamber cast to get proper measurements.

 

[MislMan]

Good to see you found the issue. I didn't notice it mentioned but, has this brass been annealed? Not really a requirement but that might help a little bit.

 

[DGP4]

I'm was beginning to think that someone used the wrong reamer when the 7MM barrel was installed. I'm surprised that the problem was the lube. I have never had my necks expand that much on my 7MM mauser!

 

[WVRJ]

You have chamber problems,no doubt about it.Someone didn't ream it right.You'll probably wind up setting the barrel back and re-doing the chamber.

 

[WVRJ]

The brass is still being overworked.Case lube is helping,but it's also hiding the underlying problem of the chamber being sloppy.I doubt it'll shoot the best.

 

[Pops70]

I have never had my necks expand that much on my 7MM mauser!

It's not really fixed if that much lube is required. But at least I can use the brass more than once.
Should they expand that much? Probably not, but in reality back then they would just throw the spent cases out, so it didn't matter.

 

[Pops70]

The brass is still being overworked.Case lube is helping,but it's also hiding the underlying problem of the chamber being sloppy.I doubt it'll shoot the best.

It's just a fun weapon for now. If I ever find a barrel with a better chamber, I can exchange it and go for better shooting results.
At least I can now play with some loads and projectile seating and not have to buy new brass all the time.

 

[Pops70]

Good to see you found the issue. I didn't notice it mentioned but, has this brass been annealed? Not really a requirement but that might help a little bit.

It was once fired factory ammo and not treated.