New Brass Seating Force Test

Recently we highlighted the Infinity APS die from Short Action Customs. Today we’re using it in the AMP Press to explore how bullet seating forces vary with different types of brass.


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The Experiment

I wanted to see how seating forces would vary by type of brass. I started with three varieties of 6.5 PRC brass: new Hornady brass, new ADG brass, and previously fired, resized Lapua brass as a control group. I did not mandrel any of this brass, which I typically do to open the necks on brand new cases.

For this session, we have the model 2 seating stem, type six base, regular cartridge centering sleeve and medium top pusher. (For more information on the SAC infinity die, watch the full video.)

To set up the AMP press, I used the test die to ensure it was functioning properly and  found zero with an unloaded case and bullet. To ensure consistency, I used the same bullet in each brass type, the Hornady 143 grain ELD-X.

I set the bullet seating depth using my dummy cartridge – in this case a loaded round of Hornady Precision Hunter ammunition. After this, I created three dummy cartridges with each type of brass. 

The Results

The previously fired and resized Lapua brass was by far the most consistent. Hornady’s new brass seemed to have the greatest variation.


Though we had a very small sample size, the kind of data you can collect with the AMP press is impressive. If I were to add annealing as a variable, I imagine I would get even more different results. This high-tech set-up worked well with the versatile SAC infinity die.

Get the Gear

SAC APS Infinity Die

Hornady 6.5 PRC Cases at Midsouth Shooters Supply and Creedmoor Sports

ADG 6.5 PRC Cases at Creedmoor Sports

AMP Press

Hornady 6.5mm 143 grain ELD-X Bullets at Midsouth Shooters Supply and Creedmoor Sports

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Gavin Gear

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