I have W760, IMR 4064 and Hornady 139 spire point B/T's.
TIA
I'll post my favoirite 140 gr. load with a strong caveat that it is way, way outside the bounds of any 280 Remington book load. I haven't checked the pressure generated, but I am quite certain it is in the 63,000 to 65,000 psi realm of a hot-loaded 130 gr. in the 270 Winchester. My rifle is a Browning Medallion with 22" barrel.
The load is R-P fire-formed cases, primer pocket uniformed and flash hole deburred, Federal 210 primer, 62 grs. RL-22, 140 gr. Sierra GameKing (boat tail) or Pro-Hunter (flat base) seated to 0.005" off the lands. This load averages 3080 fps and consistently gives less than MOA at all ranges out to 300 yards.
I say again this load is outside manual recommendations, and Alliant suggests 59.5 grs. RL-22 behind Hornady's 139 gr. SP for 3000 fps (24" barrel) @ 57,500 psi. I use the load I listed not because it gets almost 3100 fps from a 22" barrel but because it is pin-point accurate in my rifle. Case life, by the way, is good. I'll get about 12 reloads before the necks start to show stress splits.
My next favorite load is 60 grs. H-1000 behind the 150 gr. Swift Scirocco. This is also with prepared R-P brass, and the bullet is seated 0.005" off the lands, but I switch to the Federal 215 primer. The load turns 2800 fps and also gives less than MOA accuracy at all ranges out to 300 yards.
Hodgdon's #27, page 152, lists 60 grs. H-1000 behind the 150 gr. Nosler Partition for 2797 fps (24" barrel) @ 49,300 c.u.p. (about 59,000 psi). The Scirocco bullet generates more pressure than Partitions -- at least it does in the '06 -- so I suspect this load, too, is up around 62,000 to 63,000 psi based on the velocity I have recorded.
Since the maximum average SAAMI pressure for the 280 Remington is the same as the '06 (60,000 psi), I would definitely not use either of these loads in a pump or semiauto.
One of these days I might outfit my Browning Medallion with a strain gage and take some pressure readings. I just haven't brought myself around to marring the finish on that rifle yet.
The 139/140s, with whatever powder, launches them the best out of a 280 rifle. Good velocity, very accurate, lethal on deer.
140 Nosler BT
57 grains IMR4831
Rem case
Rem 91/2 primer
Haven't chrono'd but shoots .5 MOA in my 700RS.
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Say what you mean, and mean what you say.
these chrono avg. 2904fps