Custom sizing die from brass

[dogtown]

In the past with my common cartridges like .308WIN and 6.5x47, I've had custom FL sizing dies made using the dimensions of once-fired brass. These seem to do a great job of minimal sizing.

Now I've got a wildcat cartridge that I had a reamer built for. I then passed the reamer print off to the die maker to get my initial sizing and seating dies, but as I'm fireforming brass I had a thought: since they all use the same reamer spec, isn't a custom sizing dies based on fired brass, in this case, unnecessary and redundant?

Thought?

 

[Dusty Stevens]

It takes away error in reamer grinding and chambering. Fired brass is what they need to actually measure to be perfect

 

[CatShooter]

In the past with my common cartridges like .308WIN and 6.5x47, I've had custom FL sizing dies made using the dimensions of once-fired brass. These seem to do a great job of minimal sizing.

Now I've got a wildcat cartridge that I had a reamer built for. I then passed the reamer print off to the die maker to get my initial sizing and seating dies, but as I'm fireforming brass I had a thought: since they all use the same reamer spec, isn't a custom sizing dies based on fired brass, in this case, unnecessary and redundant?

Thought?

There is no "standard" reamer print - even for the factory cartridges.

 

[dogtown]

So maybe I'm not crazy and getting a custom FL sizing die isn't a bad idea? Good to know.

 

[lpreddick]

I have the feeling if you take 5 fired cases and REALLY measure them, you might get a variety of numbers. I just had my first custom/modified die set made by a whidden gunworks and they seemed to prefer a reamer print. Brass dimensions, after firing, rebound and some do so to different levels. Which one do you use to make the reamer? I like the concept of the brass conforming to the reamed chamber, not reamer conforming to fired brass. By the way, my whidden type s fl bushing die is a work of precision.