The Birth of a New Cartridge

     ‘Wildcat Cartridge’ a definition: A custom cartridge for which firearms are not mass produced or commercially available. The wildcat case is formed from a commercially available ‘parent’ case by cold forming, using custom made dies or by fire forming in the chamber of the custom built rifle. Where did it start and how did I get on this rollercoaster that is wildcatting? I enjoy my shooting and reloading, having ventured into proven wildcat cartridges I enjoy the benefits that the wildcats offer. So why did I get involved in a brand new wildcat? Because I was asked to and because I could are the only answers I have to offer.

     In the middle of August 2008 I received a ‘personal message’ from Con, a .358 calibre diehard, inviting me to go thirds in a Manson reamer for a wildcat based on the then new .300 Ruger Compact Magnum (.300RCM). The idea was to simply neck the .300RCM up to .358”. Being a relatively new inductee into the .358 Brotherhood I was already aware of the advantages of the .358 bore, cheap jacketed pistol projectiles for ‘varminting’ being one of them. So it was easy to say yes and thus started my rollercoaster ride. The first task was deciding what to call the wildcat, a few ideas were bandied about and it was decided that we would go with the politically correct ‘.358 CRG’. .358 being the diameter, CRG the first initial of the Christian names of shareholders in the reamer purchase, Chrys (Con), Richard and Greg (Rule303). 

     Con placed the order with Manson Precision Reamers, a relatively easy task conducted via email, this is where the project hit its first snag. The .300RCM was being mass produced, rifles from Ruger and ammunition from Hornady were commercially available but the cartridge hadn’t been registered so drawings weren’t yet available. Manson Precision Reamers couldn’t produce a reamer without a drawing, so we waited.

Reamer specs for the .358 CRG

   While waiting I decided to start to assemble some components. The .300RCM hadn’t hit Australian shores so most of the scouting was done off shore in the US of A. I managed to order 300 once fired .300RCM cases from oncefiredbrass.com. I reckoned by the time I’d get through the original 300 cases the .300RCM would be available in Australian gun shops. Sometime later while in my local gun shop, QLD Gun Exchange and Fishing, I found a set of Hornady .300RCM dies on the shelf, these were bought and went into the .358CRG box in the cupboard. I thought this would be a cheap option, my Gunsmith had opened Lee dies up in the past and couldn’t see any problems doing it with a set of Hornady dies. More on this later.

   After what seemed like an eternity the .300RCM was registered. Dave Manson sent a drawing of the .358CRG reamer to Con who then forwarded it on to Greg and myself. We all agreed it was what we wanted and Con placed the order for the reamer, go and no go headspace gauges. By all reports Dave Manson is a very agreeable gentleman and very easy to get along with. Meanwhile hand loaders in the US were reporting that they were unable to match the velocities of factory .300 RCM ammunition. Seems Hornady were using a secret powder / blend to achieve the advertised velocities.

     This started me thinking, what was it that we were trying to achieve by necking the .300 RCM up to .358”? I found it incredible that I had just under $500 in the project before I started to think about the justification, after all there are plenty of .35 cal cartridges already available.

 My favourite justification for all occasions “because I want to and because I can” would’ve carried me through in a pinch. The case capacity of the .300 RCM is close to the case capacity of the .350 Remington Magnum 72.7gr of water and 73.0gr of water respectively. So by increasing the neck diameter we should see an increase in capacity, so at worst we could expect to match the performance of the .350 Rem Mag in a beltless cartridge, a 225gr pill at 2700fps was a good enough reason for me to keep going with the project.

     The reamer had arrived and I needed to make a decision on an action. I had intended to use an M98 action that I had earmarked for a .416 Taylor custom build. I was convinced that a .416 Rigby in a CZ550 Safari Magnum would be a worthy replacement but was worried that the standard length of the M98 would be wasted on the short .358 CRG cartridge. Ruger had recently introduced the Hawkeye range which at the time hit the shelves for just under $900 and as a bonus they came chambered in .358 win. The Ruger MkII has a parochial following on AHN, I respect the opinions of some of the AHN members who recommend them. It was based on these recommendations that I decided to pursue a Ruger Hawkeye in .358 Win for the project. Easier said then done.

     After ringing just about every gun shop in Australia I’d given up hope of getting a .358 Win Hawkeye in less than twelve months, the aussie dollar was headed south against the US dollar which meant that new shipments would be priced accordingly. I briefly thought about chambering my .358 Win Mohawk to the .358 CRG but decided the short magazine box would be too restrictive. As luck would have it a Stainless Synthetic Hawkeye in .358 Win became available through AHN. The deal done, PTA submitted I was the owner of a near new stainless Hawkeye in .358 Win. The .358 CRG reamer would clean the .358 Win chamber up no problems. 

     All I needed now was a set of reloading dies and I’d be set to go. I’d been speaking to Jim Kent, from Buffalo Gun Smithing up the hill in Toowoomba, about machining the dies out to suit. Jim had done some work machining Lee dies for the various wild cats that his customers have ordered with no problems. The Hornady dies on the other hand were case hardened and would have to be annealed or normalised prior to machining. This presented some problems. The annealing process is a long drawn out affair with no guarantee that the die wouldn’t go out of shape during the process. The dies would have to be annealed then machined then hardened, so it was decided that it’d best if the dies were ground.

     Brisbane is a small town with a lot of small industry, which meant that lots of phone calls and lots of visits to workshops before I finally found a workshop that could do the work. I’m pleased to report that there a lot of hunters & shooters lurking in Brisbane’s Southside engineering shops. One workshop’s owner had the most amazing Hog Deer heads I have ever seen, mad keen bow hunter, but I digress. Rob from Millatech (the business formally know as Brisbane Precision Grinding) was able to open the neck area of the .300 RCM die out to .375” diameter, the work would attract a minimum charge of $100 + GST. Cheaper at half the price. 

     The whole lot was packaged up and transported up the hill to Jim Kent at Buffalo Gun Smithing. Those that know Jim will know that he’s a bit of a Ruger fan, so I left it with him. I also provided 50 once fired .300RCM cases and ten different weight and style of  .358” diameter pills, from 180gr to 250gr. Jim was confident that it would feed, and that he’d be able to increase the magazine capacity above two cartridges. So I left it with him. The relief I felt as I drove down the hill from Toowoomba was enough for to let out a woop-woop-wahooo. It’d been 53 weeks since the original PM from Con. It was finally happening, the .358 CRG was about to become a reality. 

The finished cartridge with a .22 rimfire for comparison

     Thanks and good karma vibes must go out to my two partners in crime Con and Rule303. Also to Steve99 who, for no other reason then he’s a nice bloke, gave me 5 x .350 Remington Magnum cases when I was putting together my fall back plan. I intend to publish Part 2 of this project once I start shooting the new beast.

Australian Hunting Net ©2009