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Shoot well, and hit hard.
Arild.
(And YES, I'm a NRA member!)
A few weeks ago I was contemplating the same concept of a 6.5mm wildcat based on the .270 Short Mag after reading an article about the cartridge. However, after looking at the performance data and case capacity, there was NO improvement over the performance of the 6.5mm-.284. When you toss in the fact that reamers are available, Lapua brass is available, and that die sets are available, I decided it was not worth the substantial work necessary to copy the performance of the 6.5mm-.284.
I already have a long throat 6.5mm-.284 target gun and I am just getting started on a standard throat hunting gun in the same caliber. For LR target/varmint, consider the 140gr Berger VLD bullet and for a hunting rifle a 120gr bullet. You need to first establish the weight (length) of bullet you desire in order to select the correct barrel twist. In any event, I would suggest Kreiger barrels over all others...
I am not a competitive target shooter. I just ring steel between 100-500 meters. I intend to have it set up and throated for 140 Partitions and use it for a 400 pound and under gun. I am not looking for the flatest 6.5, but it should be pretty flat.
I am not a fan of the 270, but for no real reason. The 270 WSM out performs the original by a good bit, so theoretically the 6.5 should just as easilly outperform the original 270, or am I wrong again? Lets stick with similar bullet weight ranges and fps, we should all agree on the SD and BC advantages of the 6.5(any).
In any event, I have a 6.5mm-.284 long throat that I achieve 3300fps with reasonable pressures for 120 gr bullets and 3100 fps from a 140gr bullet. I have loaded it up from this point and can hit 3400 fps with a 120gr bullet, but pressure is considerable and accuracy falls off quickly, not to mention greatly increasing throat erosion.
The point that I am making is, the short magnums are nothing new. The performance obtained from them is easily replicated in existing case designs, not to mention component availability. IF you want to wildcat a short magnum for the sake of wildcatting - go for it. However, don�t be surprised if you do a lot of work only to match existing case performance. I just think is it a lot of work and expense involved with little to no potential over existing case designs.
No harm, no foul...
If you can stick 5 rounds within 8 (or less) inches at 1000 yards, who gives a crap what the exterior ballistic trajectory looks like. Nothing is �flat� when you are shooting beyond 300 yards. Some case designs seem inherently more accurate than others, however, accuracy is more about quality actions, bullets, barrels, scopes, and proper action/chamber/barrel alignment. A bullet traveling at 3300fps dose not give a crap about the case design that got it to this velocity. All the bullet understands is its inherent ballistics potential and the environment it is traveling. A bullet will not behave or perform better from a $10,000 custom gun VS an ugly, junkyard $500 POS.
When comparing a .308 to a .300 Lapua, there is no comparison in the cartridge performance area, however, .308s can be as accurate as the .300 Lapua at 1,000 yards. So what if the .300 Lapua can squeeze another 300 to 500 fps over the .308. All this means is you gotta dial less elevation into the 300 Lapua. While this is an extreme example, the same can be said for virtually any similar case design.
If you compare the top 50 1,000 yard competition shooters and their guns, it�s the shooter that makes all the difference, not the cartridge. The guns are all very similar in design and barrels used. The bullets are mostly custom made, however, this is to ensure consistency, not impart some mysterious magic into their design.
At the end of the day, have fun building and experimenting with case designs. However, there is no magic or too many unknowns out there. Just about every case design possible has already been attempted by someone. Some work, most don�t, and few show any real improvements in existing designs.
JJ - I hope your WSM shoots lights out when you finish. Please share your observations and field experience with us. I don't trust the magazine writers to get the facts straight about anything!