6.5 CM fireformed sized brass doesn’t chamber

[Max_The_Phoenix]

Hi
I have strange issue with my 6.5cm rifle.

My fireformed brass chambers easily
But resized using SAC FL sizing die wont. (No expander, 287 bushing)
I tried Hornady match grade bushing die as well.

I have to bump the shoulders back about 0.0045 (1.4845)in order to chamber the sized brass. (Bolt striped without ejector and firing pin)


Measurements using SAC headspace gage for factory ammo and my hand loads are the same:

Fireformed:
Base to shoulder 1.489
Web: 0.470
Neck: 0.295
O.A.L: 1.920

Note: 2 times fired brass was 1.4860-14865 base to shoulder on all cases.
Go and
Now once fired factory brass and my handload on the 3rd firing measures 1.4885-1.4890 that made me scratch my head for the past 2 weeks.
300 rounds down the pipe.


Sized:
Base to shoulder: 1.4865
Neck: 0.288
Web: 0.470
O.A.L: trimmed to 1.910


My questions

• Is 4.5 thou shoulder bump a lot for brass life longevity?
• How can I make it work for only 2 thou shoulder bump?

Any suggestions will be appreciated.

 

[straightshooter1]

Hi
I have strange issue with my 6.5cm rifle.

My fireformed brass chambers easily
But resized using SAC FL sizing die wont. (No expander, 287 bushing)
I tried Hornady match grade bushing die as well.

I have to bump the shoulders back about 0.0045 (1.4845)in order to chamber the sized brass. (Bolt striped without ejector and firing pin)


Measurements using SAC headspace gage for factory ammo and my hand loads are the same:

Fireformed:
Base to shoulder 1.489
Web: 0.470
Neck: 0.295
O.A.L: 1.920

Note: 2 times fired brass was 1.4860-14865 base to shoulder on all cases.
Go and
Now once fired factory brass and my handload on the 3rd firing measures 1.4885-1.4890 that made me scratch my head for the past 2 weeks.
300 rounds down the pipe.


Sized:
Base to shoulder: 1.4865
Neck: 0.288
Web: 0.470
O.A.L: trimmed to 1.910


My questions

• Is 4.5 thou shoulder bump a lot for brass life longevity?
• How can I make it work for only 2 thou shoulder bump?

Any suggestions will be appreciated.

I'd take a close look at what the bushing is doing when sizing, like maybe the false shoulder above the neck-shoulder junction that the bushing leaves is being expanded in the sizing process??? If you can fix this, you shouldn't have a problem going with a .002, over even less, bump.

Yes, .0045 shoulder bump is a lot to be doing repeatedly and will not give you long brass like.

 

[spife7980]

But that said the 2x fired measures 1.486 and he sizes to 1.484 to chamber. That jives which makes me suspect the initial 1.489 measurements being faulty.

OP: are these measurements the same with both the sac die and the hornady? Or does the hornady size the web more.

What’s the shoulder diameter: fired vs sized

Were primers removed for that first measurement?

 

[Max_The_Phoenix]

But that said the 2x fired measures 1.486 and he sizes to 1.484 to chamber. That jives which makes me suspect the initial 1.489 measurements being faulty.

OP: are these measurements the same with both the sac die and the hornady? Or does the hornady size the web more.

What’s the shoulder diameter: fired vs sized

We’re primers removed for that first measurement?

But that said the 2x fired measures 1.486 and he sizes to 1.484 to chamber. That jives which makes me suspect the initial 1.489 measurements being faulty.

OP: are these measurements the same with both the sac die and the hornady? Or does the hornady size the web more.

What’s the shoulder diameter: fired vs sized

We’re primers removed for that first measurement?

The measurements confirmed with at least 30 cases.
Yes both hornady and SAC size the web and measurements are the same

I even tried sizing with RCBS small base die, I had to size down to 1.4845

Bottom of the Shoulder dimension for sized is 0.4615 and Fired is 0.463
Primers were removed.

 

[TheOfficeT-Rex]

Might be time to take a sized case that won’t chamber, give it a sharpie coloring and see where it hangs up. Might be easier to troubleshoot from there.