300PRC Build

[BATattack]

International rules allow for any cal under 8mm. Even with this rule being much less restrictive than many Australian ranges you won't see many world class shooters using anything bigger than a 300wsm.

Most common Cal's would be

.284
7mm RSAUM
7mm-6.5PRC (6.5PRC necked up to 7mm or similar variant)
300wsm

Cal's in that realm seem to be an optimum balance between precision, bullet BC, barrel life and recoil in a 10kg gun (no muzzle brakes remember)

[PeteFox]

The velocity limit for a given bullet weight is relatively easy to calculate.
SAAMI have the formula here >>. https://saami.org/glossary/kinetic-ener ... quation,V2)%2F(14000*gc).

To work out the maximum velocity for a given bullet weight and energy limit the formula can be re- jigged as : V = sqrt(450,436 x 3500 / projectile mass in grains)

I plugged the formula into Excel and graph and table of results is below. The line in the graph is at 3500 ft/lb energy

energy limits.jpg

The table lists the maximum speeds for the given weight projectiles to be at 3500ft/lb energy. Items in red are above max velocity.

velocity limits.jpg

It shows that big 30 cal bullets can't be driven hard and be within the limits and anything above 30-06 size may be too much gun. 30SAUM and 300WSM would need a reduced powder load which sort of defeats the purpose.

Pete

[Matt P]

Not every range has a 3500 ft/lb restriction, there are many ranges in NSW that have 4125 ft/lb limits and even a few that allow 338 Lap. As mentioned earlier it’s not the NRAA that implements these restrictions. Unfortunately there isn’t a organised ELR competition in Australia that I know of.

[macguru]

I guess a list of ranges and their limits would be a good thing, if anyone has that information available

[RDavies]

Around the world, the top shooters have gravitated to a limited amount of cases such as 6.5/7mm PRC (and its similar wildcats), 7 SAUM, 7mm/270WSM (or 7mm/300WSM) and 300WSM, with a few pushing 284 based wildcats hard at close to SAUM speeds as being the best compromised between inherent accuracy, recoil tolerance, ease of keeping in tune, fouling and wind bucking. If the bigger cartridges were an advantage, trust me, the top shooters would've certainly tried them. At the last few World Championships, the above cartridges were used by almost everyone and I am confident I could say EVERYONE in the top 50. And this is shooting at all long distance, with the individuals being pair or triples fired on manual targets for 15-20 shots so would suit the bigger calibers. I do know some people who did try bigger cases but didn't take them or didn't find them as consistent.

Even though the most recent world championship did not have any energy limits, I am fairly confident that in the individuals (3 to a mound slow fire), no one used anything which would've gone over the 4125 lb/ft limit still allowed at many ranges. In the teams shoots which were fired string fire on manual targets, so a bit slower than in usually shot in Australia, very few would've used cartridges which would've been substantially over the 3500 lb/ft limit even though barrel life and cost would not have been a factor and all shooting was done at long range.

With shooting in Australia now more different to what is shot in other countries, there is now even less call for bigger cartridges. With our shorter distances usually being shot and much faster rate of fire, there is less need for the bigger, wind bucking cartridges for the majority of competitions here. If I shot more pairs or triples (Bisley style) comps or Match rifle (1000-1200 yds and some 1500yds) I would seriously consider a 300 WSM, which I do love, but nothing bigger. As not many people in Australia shoot these style of competitions any longer, very few would do better with anything bigger than 6.5/7mm PRC or 7 SAUM, and a lot of people would be best served by 284 based cartridges.