reloading the 6mm-284 & 7mm-378

lawdog44

I was looking for some loading imformation anybody have an idea where I might start or have any to share ?

thanks lawdog44

ern98

Many of the new versions of the common reloading manuals have this cartridge listed. I picked up a copy of the Barnes so as to get data on this round. Still you have to do your own load development as this is mostly still a wildcat and has many variations. Barrel length alone will cause much variance between rifles. The 1000yd shooters are useing 28" and longer barrels. My hunting rifle has only a 23.5" barrel. Start a couple of grains low and work up from there. A chronograph and a set of caliphers will help alot in deciding which is the best load.

nononsense

lawdog44,

The .284 family of wildcat cartridges can be referenced through the similar cartridges based on the -'06 case because the two cases have a similar capacity. But the 6mm-06 has very little information as opposed to something like the standardized 25-06 cartridge. To skirt this, the easiest spot to begin is with the .240 Weatherby. Again, the case capacity is similar to the -'06 case but you still need to start low and work your way up slowly and safely.

The 7mm-378 WBY is a good idea (.378 WBY) taken to its worst extreme. I've worked with the 30-378 WBY and the 338-378 WBY and managed to get usable loads for hunting but always with much longer barrels than we as hunters are normally used to to carrying in the field. The powders required to fuel these behemoths resembles charcoal rather than smokeless gunpowder. Only the very slowest powders will even come close to providing some inkling of performance that we expect from this case capacity and then only with LONG barrels, something in the range of 30" or more and more is better in this example. This is NOT a sporting rifle cartridge, so if that's what you're looking for, I suggest trying a different idea.

There will be about 3 or 4 powders that will be suitable for loading in this cartridge and then only with the heaviest bullets: 50 BMG in all of its varieties, V V-20N29, WC860 and you can ask some of the surplus powder suppliers about WC872 as a possibility. If the WC872 will work then you can consider the AA-8700 as having some potential. I think its going to be too fast as a ball powder personally.

The throat ahead of this chamber will not last for very long, maybe as short as 4-500 shots, if that many. This idea is tantamount to setting off a blowtorch in your barrel each time you pull the trigger.

There are at least a couple of cartridges that will equal the performance that you might get with the 7mm-378 and they won't require custom dies, a custom reamer and an extra long barrel to accomplish your goals. Consider something along the lines of the 7mm RUM.

Here are a couple of links for reloading information:

http://www.reloadersnest.com/frontpage.asp?CaliberID=103

http://www.handloads.com/loaddata/default.asp

Best of luck with your projects.