Many years ago when i was doing a lot of "wildcatting" one of things i wanted to do was, to get a bit more velocity out of my 9.3x74R double rifle. I also wanted the option, if needed, to beable to shoot factory rounds in it too. So i came up with a design that took some of the "taper" out of the parent case, and also moved the shoulder foreward a bit. This gives the case shoulder more surface to headspace on to hold case stretching to a mininum, along with giveing the case more capacity too.

Anyway, here's the design i came up with,



It was one of the last projects i worked on, and i never got around to wringing it out, but i hope to fix all of that as soon as it warms up a bit... I've chronographed quite a few loads out of these bbls in the past, so i "will" have something to compare the new design to.

You can clearly see the difference between a "factory" 74R case, and the "fireformed" case in the pict... The bullets in the two loaded cases are loaded with 286 NP's...

Next i need to work up new loads in the fireformed cases, and see what the velocity improvements are, while keeping the pressures "near" the origional design... I know it will easily pick up 100 fps, and maybe even 200???

The extra velocity should make the bigger bullets open up better at longer ranges on thin skined animials like deer, and the best part is, with the Valmet regulation will be no problem at all.

So,stay tuned...

DM

"The extra velocity should make the bigger bullets open up better at longer ranges on thin skined animials like deer"

Only 80 yards or so, but I've been pretty impressed at how 286 NPs work on deer from a "stock" 9,3x74R.





Sounds like a cool project anyway.....

Nosler custom ammo has 9.3x74r/286gn clocked at 2430fps. Maybe that loading is specific for falling block actions only,but if not, then you obviously have room to increase MV with yourcat.

What action is this intended for?? Is it for the breaktop (double - Valmet/Tikka?) gun displayed in your picture, or is that gun simply displayed as part of an illustration?? If this is the type of gun you are loading and wildcatting for, do you know the pressures you'll generate with your wildcat, and do you know what force (pressure x case head area) your gun is made to deal with??

I can see the attraction of wildcatting in a bolt action or falling block single shot. I don't think I'd personally dick with breaktops (Jaeger Verschluss excluded, perhaps), unless you have inside knowledge of pressure, force and what the gun is designed to handle. At best you might shoot your gun loose, at worst you might create real danger for yourself and others. All that for 100 fps extra from a cartridge, which has been shown to work superbly as it is over the years.

- mike

quote:

What action is this intended for?? Is it for the breaktop (double - Valmet/Tikka?) gun displayed in your picture, or is that gun simply displayed as part of an illustration?? If this is the type of gun you are loading and wildcatting for, do you know the pressures you'll generate with your wildcat, and do you know what force (pressure x case head area) your gun is made to deal with??

The "fast" answer is "yes" the 412 is the gun it's chambered in, and "NO not exactly", to the rest of your question.

The "slow" answer is: What i DO know is that i designed the below pictured cartridges "long" before i came up with the 74R imp... I came up with all of the dimensions ect.. and Fred Huntington gave them the name when i sent them in to have some custom dies made.



(left to right... 416RDS, 375RDS, 338RDS, and a 30-06 for comparison)

AND, i've fired hundreds and hundreds of them myself useing the "same" action pictured in my origional post. I sold quite a few in 375, and at least two owners took them to africa flattening numerous animials. Also they were used in Alaska extensively!

I mfg'd new ammo and brass for them and sold it retail. I also swaged .375 cal. "bonded core" bullets of my own design and loaded them in the 375's. This is before everyone got on the "bonded core" wagon. I could sell all i cared to make untill i got sick of makeing them and moved on to more interesting projects.

After all of that, i've NOT had one pressure problem or any problems with my action loosening up one bit. With experience you learn what to look for and deal with it as you go... Also it doesn't hurt that i have my bbls fit "properly" to my action.

The 9.3x74Rimp is a pussycat compared to what my 412 has been through!

DM

I guess an empirical approach is better than no approach at all.
- mike

Thanks for the heads up here DM. I had forgotten about it. This looks like an idea whose time has come. You will get less back thrust with the straighter case; less body taper. I would be interested in 100 or 200 extra fps almost for free. The improved case life would be a positive result as well. Are you going to test and regulate it soon? We may have to talk more. Packy

I started thinking about this. Scary I know. A packrat thinking! Have you considered using VihtaVouri N540? It may or may not give you more fps. Might or might not be able to switch from 540 to other loads for regulation. Just a free thought. It might be worth what you paid for it and expensive powder to top it off. Good luck. Packy