Resizing issue- extreme pressure required

I was resizing some 6.5 creedmoor and 300 Win Mag brass last night. The 6.5 dies are brand new. The brass is Starline brass bought new and fired once. The initial resizing was nothing more than me making sure the case mouths were round. The 300 WM brass was bought new from Gunwerks and has been fired 1 or 2 times. I’ve been using the 300 dies for over 30 years. For some reason last night it took an extreme amount of force to resize the brass. I was using the same lube and procedure I’ve used for years. I thought I was going to break the bench. I polished the expander on the new die and cleaned the die but it did not help. Never had to use this kind of force. The only thing different is the brass for the 300. The brass and the die are new for the 6.5. Can different brands of brass be more difficult than others to resize? I’ve never used either of these brands before. It was a workout to do a few pieces.
Any thoughts would be appreciated.

 

Yes, different brands of brass can be more difficult than others to resize depending on the thickness of the brass as well as the extent of annealing. Brass thickness trying to squeeze between the expander and the die will require more force as thickness increases.

 

You might try screwing the expander down in the die deeper.. if its up in the area of the neck the neck sizing part of the die might be squeezing it down while the expander is trying to open it up.. in other words make sure the expander is below the neck sizing part of the die

 

Try polishing the inside of the die with a shotgun cleaning mop and J&B Bore Paiste.

If you are lazy like me just disassemble the die and put the die body in a vibratory tumbler with treated walnut media and tumble overnight.

I'm thinking the die may have gotten dirty on the inside and causing the increased effort.

 

Isn't there and issue with resizing some belted magnums that require a special sizing die? Atleast I remember it that way when I have the 7mm mag urge now and then.

 

Also take a few measurements before and after sizing

 

Cleaned the hole in the sizing die? Allows air to escape when the lubed brass is sealed to the interior of the die.

Essentially, you may have hydraulic the brass and die.

 

Sounds like the only thing new in your loading is the new brass. I would start by measuring the twice fired Starline base and whatever cases you been using.

 

RCBS sizing die?

 

Make sure the depriming pin is not to large to go through the hole without pressure (yes I've seen them to big) also make sure it is not bent and causing you trouble.

 

This ^^^