Wildcat Loading: Off the Shelf Without Custom Dies

When people think of “wildcatting,” they think of custom dies and expensive setups. Did you know it doesn’t have to be that way? I’ll show you how to load a wildcat cartridge with an RCBS Rockchucker and dies!

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What are Wildcats?

SAAMI-approved cartridges have published specifications that every manufacturer follows for the chambering, ammunition, and dies. .308 is a perfect example of this. “Wildcat” cartridges do not fit into a SAAMI-spec, but are derived from SAAMI-spec cases to serve a specific purpose. The cartridge I shot in F-Class competition, 7 PRCW, is one such wildcat. The 7 PRCW is a 6.5 PRC case necked up to .284.

Since the only change is in the bullet diameter, .264 to .284, custom dies are not needed.

Set-Up and Fireforming

My press setup consists of an RCBS Rock Chucker Supreme on an InLine Fabrication Ultramount. 7 PRCW is a pretty simple wildcat, not all will be this easy.

I replaced the 6.5mm expander ball in the 6.5 PRC sizing die with a 7mm expander ball and removed the bushing.

Next, I lubed the case necks of virgin Lapua 6.5 PRC brass with foam tips and opened the case necks just enough for a 7mm bullet to fit.

Priming, loading this brass, and shooting it will “fireform it”, meaning it expands to my desired 7 PRCW chamber dimensions.

Working with Fireformed Cases

The resizing process is a bit different with fireformed cases. A 7 PRCW chamber is very close to a standard 6.5 PRC chamber, so the die body taper of the 6.5 PRC full-length sizing die will do just fine. What needs to change is the neck bushing. I like to use a .305 bushing in the full-length body die.

When I install a bushing, I screw it down all of the way until it hits, then back it off slightly and shake it. I listen for a slight rattle indicating the bushing has a little bit of float. I screwed this assembly back into the die and set it up appropriately. Next, I lubed the fireformed cases and zeroed them on dial calipers to ensure proper sizing.

After resizing and decapping all of the cases, I primed them on the press using the RCBS ram priming unit and checked the runout of each case using a Sinclair concentricity gauge.

After trimming, chamfering, and deburring each chase, it was time to add powder.

I used the RCBS MatchMaster powder dispenser and RCBS MatchMaster funnel kit to fill each case.

I seated each bullet to a cartridge OAL of 2.314”, dropping each bullet neatly into the MatchMaster die’s dedicated port.

Shooting

I took these loaded rounds out to 600 yards for testing, battling 10-20 mph winds and near-freezing temperatures.

My first three-shot group measured 0.84 MOA on a Shotmarker e-target. As I settled in and adjusted my tuner, my three-shot group size shrunk to 0.28 MOA.

Including a wide flyer lost to wind, 14 shots yielded a 1.62 MOA group at 600 yards. These were not ideal testing conditions, but sometimes you have to work with what you have.

In my opinion, this load could still use some refinement, especially since I have not done extensive testing with Ramshot Hunter.

Conclusion

This demonstration shows that some wildcats can be loaded with slight tweaks to dies and equipment you already have or can easily and affordably procure.