6.5 RPM what is it good for?

[just_jon]

Jon, seriously you topped out at 3170 with US869? I understand topping out with N570 as I did as well at 3150. Very disappointed to say the least.
But US869 has been the best powder I played with. My 153.5 BERGERS are past 3250 with zero pressure. As soon as it cools off to sub 50° I'll be back pushing forward to find pressure. I feel 3300-3350 should be very easy. Just shocked at you peaked at 3170 with US869.
Is your rifle a Weatherby or ? Just trying to figure how you topped out so low with US869.

6.5x300 WBY - This is my first time using US869 and the results are indeed disappointing. I wasted a bunch of powder testing the 144 and 156 Bergers. Most of my testing was done in 70-80 degree temps which may have been a contributing factor. Since I have a bunch, I don't plan on giving up on US869 and will be back to testing in cooler temps. Rifle is a Weatherby Vanguard.

Jon

 

[Calvin45]

I've tested the 123AH and 124HH:

123AH
RL17: 71.0 gr @ 3580 fps. Hit pressure at 70.0 grains.
RL22: 78.0 gr @ 3507 fps. Hit pressure at 77.0 grains.
IMR 7828 SSC: 78.0 gr @ 3,385 fps. Never got to pressure.
H4350: 70.5 @ 3,457 fps. Hit pressure at 70.5 grains.

124HH
IMR 7828 SSC: 77.5 gr @ 3426 fps. Never got to pressure.
RL25: 80.0 gr @ 3381 fps. Never got to pressure.
N570: 81.0 gr @ 3573). Never got to pressure.

I have a bunch of 80HHT and 85HH that I plan on testing this fall. QL estimates RL16 can push the 85HH at 4240 fps. The 80HHT should do a bit better.

Holy smokes that's actually kinda slow with those 124s for what I thought this case would do, when I consider that the much smaller case 270 Winchester can exceed 3200 with bullets in that weight range under the right circumstances. But I suppose diminishing returns and overbore cases especially being more efficient with heavy pills.

I bet you easily hit 4250 with those 80/85 grain pills. My 24 inch barreled 257 weatherby hit 4170 with the 75 grain hammer hunter (HBN treated) and reloader 17 before hitting pressure signs.

 

[Bobhunts]

Hey Horsemen61,

I don't have one, but I have a 6.5-300 Weatherby mag. But the idea of the 6.5 RPM was to maximize the 6 lug action that Weatherby produces for their standard length action. So they blew out a 284 and lengthened it to increase powder capacity and allow a magnum cartridge fit in their lights action and then developed the Backcountry rifle for it. Lightweight rifle that hits harder than most can usually get that light while remaining stock off the shelf.

It's faster than the PRC by 50-100 fps and is a cool rebated rim Weatherby cartridge. It's not as fast or overbore as the 26 Nosler or the big daddy 6.5-300 Wby though.

I had one built from a trued Rem 700 action and am still in load development. I quit as I loaned my Garmin Xero to a buddy that drew a Nevada Elk tag. So far at the mid range of loads I am at 3112 average with 63.5 grns of H100.

 

[6.5x300 WBY]

6.5x300 WBY - This is my first time using US869 and the results are indeed disappointing. I wasted a bunch of powder testing the 144 and 156 Bergers. Most of my testing was done in 70-80 degree temps which may have been a contributing factor. Since I have a bunch, I don't plan on giving up on US869 and will be back to testing in cooler temps. Rifle is a Weatherby Vanguard.

Jon

Yup ok makes sense. I only do load testing at or below 50° for the 6.5x300.

Thx for the info. Hey would love to hear about those super light weight Hammers.

 

[K.E.C. Darkside]

I had one built from a trued Rem 700 action and am still in load development. I quit as I loaned my Garmin Xero to a buddy that drew a Nevada Elk tag. So far at the mid range of loads I am at 3112 average with 63.5 grns of H100.

Howdy, good to see someone build a custom 6.5/300. I have been thinking of doing a custom with the MB3 Wyatt mag box. To be able to get full case capacity a 3.825oal would be nice. I have a Mark V Accumark and I can't see how anyone can install a bigger box in one. Maybe someone out there knows how to do it. What size box are you using. Thanks David

 

[6.5x300 WBY]

Oops

 

[Bobhunts]

Howdy, good to see someone build a custom 6.5/300. I have been thinking of doing a custom with the MB3 Wyatt mag box. To be able to get full case capacity a 3.825oal would be nice. I have a Mark V Accumark and I can't see how anyone can install a bigger box in one. Maybe someone out there knows how to do it. What size box are you using. Thanks David

I built a 6.5 RPM.