Andrew Massi
Well-Known Member
H4831sc, imr 4955 both gave equal velocity as rl26 but with better sd and temp stability with the 124hh
Cranking up the RPM
- Thread starter Swamplord
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I am wondering why saami has Max pressure on the 6.5rpm at 65k psi, when the 6.5-284 and 284win are both at 58k psi.
It sounds like the rebated rim on the 284 is what decreases that max pressure, so how could a case that's just longer handle more pressure? The only other difference I see in the design is that the rpm chamber has a taper of about 0.013/in and the 284win has a taper of about 0.016/in. I wouldn't think that tiny change could allow a significant bump in pressure.
It sounds like the rebated rim on the 284 is what decreases that max pressure, so how could a case that's just longer handle more pressure? The only other difference I see in the design is that the rpm chamber has a taper of about 0.013/in and the 284win has a taper of about 0.016/in. I wouldn't think that tiny change could allow a significant bump in pressure.
Andrew Massi
Well-Known Member
It's a modern cartridge with modern powders. Look at the 6.5 creedmoor(62k)and 6.5 prc.(65k)
Andrew Massi
Well-Known Member
Both
Yes but 6.5-284 is new. The 100+ year old '06 max is 60k psi. The 280ai is at 65k and that's not even the original AI design
The 284 case is known to show pressure signs on the head at lower pressures and it's largely thought to be because of the rebated rim being so much smaller than the base. Saum and wsm cases are rebated, but the difference in size between base and head isn't as great.
Andrew Massi
Well-Known Member
The 284 case may show that if bullets are seated into the powder column also the 284 win was standardized around a semi auto (model 100)and lever action(88) short rifle so that must be taken into account- those actions are considerably weaker and more pressure sensitive than a bolt.action(especially weatherbys six lug. A very strong action)
.473 case heads have proven to be capable of exceeding 65k
Manufacturers who wish to establish a saami cartridge get to set that psi rating, saami then tests it and determines if it's safe.
When norma standardized the wildcat 6.5-284 they decided what psi rating met their needs(barrel life, brass life et el)
nosler same for the 280ai.
Weatherby developed a case that is capable of routinely handling ,65k psi and they gave that design to saami for testing. Saami merely approves their design as being reasonably safe in modern actions, bullets, powders et el.
5 hours ago Weatherby announced the arrival of the 338 WBY RPM on their Facebook page ...
very cool, more brass for my 358 RIPM and less work necking up, than from the 6.5 RPM I am using
and everybody thought it would be the 7mm RPM next .....
weatherby.com
...
very cool, more brass for my 358 RIPM and less work necking up, than from the 6.5 RPM I am using
and everybody thought it would be the 7mm RPM next .....
338 WBY RPM - Weatherby, Inc.
338 WBY RPM Rebated Precision Magnum We’re proud to announce that the sixteenth Weatherby® Magnum cartridge has gained acceptance into the SAAMI Standards. Several years in the making, the 338 Weatherby Rebated Precision Magnum (WBY RPM) is the latest in a long line of innovative Weatherby...
weatherby.com
Calvin45
Well-Known Member
How would this compare to the very old .338 win mag? Besides the belt. Interesting, looks good in the picture.5 hours ago Weatherby announced the arrival of the 338 WBY RPM on their Facebook page ...
very cool, more brass for my 358 RIPM and less work necking up, than from the 6.5 RPM I am using
and everybody thought it would be the 7mm RPM next .....
...View attachment 337856338 WBY RPM - Weatherby, Inc.
338 WBY RPM Rebated Precision Magnum We’re proud to announce that the sixteenth Weatherby® Magnum cartridge has gained acceptance into the SAAMI Standards. Several years in the making, the 338 Weatherby Rebated Precision Magnum (WBY RPM) is the latest in a long line of innovative Weatherby...
Calvin45
Well-Known Member
Good for them for focusing on meeting demand for existing products as first priority!!!!!!!!!
my only concern is brass quality, you dont hear much on it.
if you have to download to get any decent case life 3-5 reloads then it aint worth it, but if you can match the 338 win mag and then get 5 or more reloads it becomes a nice option
if you have to download to get any decent case life 3-5 reloads then it aint worth it, but if you can match the 338 win mag and then get 5 or more reloads it becomes a nice option
