Home Forums Hunting & Shooting Ask The Gunwriters 6.5 Weatherby RPM Mo betta than a 280 Ackley Improved????

Weatherby advertises the 6.5 Weatherby RPM 140-grain Nosler Accubond bullet to 3,075 fps


I'm spinning that same weight 140 AB at 3,100 out of a 22" barrel in 280 AI.

JBM Ballistics tale of the tape

6.5 WBY at 600 yds -49.3......800 yds --117.1
280 AI at ..600 yds -49.4.......800 yds --117.9

No.

7mm, is larger in diameter !
More whack !!
I have a 280ai, so I am biased.

SU35,

Since you didn't list how what zero/scope height you used for your calculations, I ran JBM with Bryan Litz's BC's with a 100-yard zero, 1.5" scope height--and 5 mph 90-degree wind, and wind generally the real problem at extended ranges, not drop. Here's what resulted.

6.5mm 140 AB @ 3075:
157.4 inch drop at 800
26.1 inch wind drift
1625 fps

7mm 140 AB @ 3100:
163.4 inch drop at 800
29.1 inch wind drift
1537 fps

Haha!...you honor me.

As most here would know from my time here on the fire I've been a 6.5 guy since almost forever.

But I have this 700 Ti that I put a factory mountain rifle barrel in 280 that had been punched Ackley.
Couldn't help but want to compare to the latest 6.5 design. Think I'll keep it at 280 Ack. It is also a better cross over for mountain elk.



I went off a 2.6" 100 yd zero and 4,500' elevation Nosler BC's

Copied from JBM

....Range Drop Drop Windage Velocity

6.5... 800 -117.1 -14.0 38.2 4.6 1890.2
7mm 800 -117.9 -14.1 40.2 4.8 1858.5


What were Bryan Litz's BC's ?

140 6.5mm--.463 G7
140 7mm--.424 G7

These are averages down to 1500 fps, and are derived both from chronographing and various other factors, including form factors derived from measurements of the bullets.

I have found Bryan's BCs very accurate at longer ranges, which is why I depend on them when testing rifles/scopes/bullets on the local 1000-yard range. They save a lot of time and ammo!

No kidding, what media can get I get a hold of to see his BC's?

I grabbed a box of 6.5 RPM ammo the other day and pulled the 140gr Accubond, powder charge weighed 64.6grs, the case held 80.1grs of water, the second one held 80.8grs of water, its simply just a 6.5-284 extended, here's a cpl pictures with a

6.5-284 / 6.5 RPM / 280 Ackley




6.5-284 / 6.5 RPM / 280 Ackley / empty 6.5 RPM



Article from a magazine with measured H20 weights

You can check out his website, www.appliedballistics.com--but I end up buying the latest edition of his book, BALLISTIC PERFORMANCE OF RIFLE BULLETS, so I can have the latest, best info on hand. It also includes chapters with lots of excellent ancillary info.

Thank you MD, very much!

BCCP, excellent photos! That RPM case necked up shows some great potential.