6.5 RPM what is it good for?

6.5x300 WBY said:

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.

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just_jon said:

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.

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NorthernShot said:

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.

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just_jon said:

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

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Bobhunts said:

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.

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K.E.C. Darkside said:

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

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