7mm mag case sizing

[BW64]

First time fired & sizing in Lee FL die I get this. Seems like the die is crushing the case. Oal of case is ppl er specs. However shouldres grew .025 when fired.

BW

 

[CoyoteTan]

Throw away the Lee dies and order Redding dies.

 

[M-61]

A bit of info first. Is this fired in a factory rifle? If so whose?

 

[BW64]

Fired in Savage 111 with new x caliber barrel. Also I've used Lee dies for years with no problems at all.

BW

 

[M-61]

PM sent

 

[243winxb]

The diameter when the line is, before and after sizing would help. Compare diameter at http://www.saami.org/specifications_and_information/index.cfm



A change in lube may help.

shouldres grew .025 when fired.

This can cause the brass to stretch, resulting in a separation. But not normally on the first firing. I dont think this is your problem?

 

[BW64]

The diameter when the line is, before and after sizing would help. Compare diameter at http://www.saami.org/specifications_and_information/index.cfm

Does the dies mouth have a bevel?

A change in lube may help.

This can cause the brass to stretch, resulting in a separation. But not normally on the first firing. I dont think this is your problem?

View attachment 1043254

They measure .517 at the point just above the belt. Specs say .512. Also I just noticed there is a shiny ring just above the belt right after firing. Could the head space be off?? Again first time with belted cartridge. Thanks.

BW

 

[BW64]

Here's one that was only fired. Can you see the mark above the belt??

 

[243winxb]

They measure .517

Looks like a maximum chamber. .5166" is SAAMI's maximum.

new x caliber barrel.

shouldres grew .025 when fired.

Could the head space be off??

. Could be?

You need headspace gauges to check it. Headspace is on the belt.

The end of the chamber is something else.

 

[BW64]

DAM!!! I knew I should have gone with a non belted cartridge!!


BW

 

[BW64]

Yes used the gauge for headspace.

BW

 

[243winxb]

Post 8 photo does not look like a start of a separation. The ones i have seen are very thin and bright.

 

[243winxb]

The chambers diameter is oversize? Your brass measurement would be after spring back. Meaning the chamber is even larger?
This is my guess.

 

[BW64]

The chambers diameter is oversize? Your brass measurement would be after spring back. Meaning the chamber is even larger?
This is my guess.

AGAIN!! I had the same problem with a 6.5 cm barrel from Mcgowen!! But those cases would not fit in my Wilson seater die. Left 1/4" sticking out.

BW

 

[243winxb]

This is my guess.

Wait for more opinions. I am not a gunsmith.

 

[Bart B.]

That's normal with belted cases. A .015" wide shiny ring in front of the belt happens with maximum chamber belt headspace (.227") and minimum case belt headspace (.212") for 7 Rem Mag. It's the unsupported part of the case body exactly like rimless cases have about 1/10th inch forward of their extractor groove when case heads are against bolt faces at peak pressure.

SAAMI specs ....... .516" chamber diameter in front of its headspace shoulder. 2.109" is minimum case head to shoulder. 2.135" is maximum bolt face to chamber shoulder, a .026" difference.

 

[jepp2]

DAM!!! I knew I should have gone with a non belted cartridge!!

It will be just fine. Just takes some time to get used to the differences. Don't make the mistake of setting your die to headspace off the belt after the first firing. Set it off the shoulder just like other cartridges. The growth you saw is common on the first firing. The factory loads were set up to head space off the belt.

 

[BW64]

It will be just fine. Just takes some time to get used to the differences. Don't make the mistake of setting your die to headspace off the belt after the first firing. Set it off the shoulder just like other cartridges. The growth you saw is common on the first firing. The factory loads were set up to head space off the belt.

Please explain. My .308 & 6.5cm are set as per factory. I only neck size those.

BW

 

[Dusty Stevens]

Please explain. My .308 & 6.5cm are set as per factory. I only neck size those.

BW

They headspace off the shoulder where the belted mag headspaces off the belt. As for neck sizing the others thatll be a problem for a future post. Id try a different set of dies. Looks like your chamber is big and your dies are small and without a chamfer. Theyre digging into the brass instead of sliding over the bulge.

 

[jepp2]

My .308 & 6.5cm are set as per factory. I only neck size those.

When you say "set as per factory" please explain what you mean.

Many folks have been told the belted mags headspace off the belt. And if that is how you approach it, you will get about 3 load/firings until the cases have incipient case head separations. You just can't move the should close to 0.020" without stretching the case near the belt.

I don't know how you set your dies for your 308 & 6.5 CM, but when I set mine, I goal to only set the shoulder back 0.002" from the datum to case head length that will contact the shoulder of your chamber. To find this, I measure a fired case you can feel the bolt close on. Assuming you do something similar, just set your die the same for the belted magnum. Future firings will headspace off the shoulder, just like your other cartridges.

I really don't neck size very often anymore. I do use a body die and a collet die on many cartridges. The rest I use a FL sizing die that I have honed the die neck to the diameter I want so the expander only opens up the case neck 0.0005".