Can someone tell me what this round is, parent case, and where to find load data for it? Thanks.

The 240 Gibbs is an 06 case. blown out to around .455 at the shoulder with the shoulder moved forward. Neck is approximately .25" and shoulder is 35 deg.

http://stevespages.com/jpg/cd240gibbs.jpg


Burning around 60 grs of powder you can move an 85 gr bullet around 3450-3500FPS. A 240 Wby gives you around the same velocity with about 7-10grs less. I built my own version years ago on an improved 280 case. I had about 1.5-2grs more capacity. The case is WAY overbore. I burned the throat out of mine to the point I couldn't reach the lands in less than 1000rds. Closer to 6-700.

This is from the Gibbs Articles:


For the 243 I think a slightly improved 6mmrem case gets you the best bang for the $.

here's some (max loads) data


75 Hodgdon H-450 66.0 3,602
Remarks: OAL = 3.060 inches
75 Hodgdon H-4350 59.0 3,597
Remarks: OAL = 3.060 inches
75 Hodgdon H-870 71.0 3,596
Remarks: OAL = 3.060 inches
75 IMR IMR-4831 60.0 3,589
Remarks: OAL = 3.060 inches
75 Hodgdon H-4831 63.0 3,556
Remarks: OAL = 3.060 inches
75 IMR IMR-7828 63.0 3,511
Remarks: OAL = 3.060 inches
75 Alliant RL-22 63.0 3,665
Remarks: OAL = 3.060 inches
85 Hodgdon H-870 69.0 3,500
Remarks: OAL = 3.110 inches
85 Hodgdon H-450 64.0 3,461
Remarks: OAL = 3.110 inches
85 IMR IMR-4831 59.0 3,460
Remarks: OAL = 3.110 inches
85 Hodgdon H-4350 58.0 3,452
Remarks: OAL = 3.110 inches
85 IMR IMR-7828 62.0 3,449
Remarks: OAL = 3.110 inches
85 Hodgdon H-4831 61.0 3,420
Remarks: OAL = 3.110 inches
85 Alliant RL-22 61.0 3,469
Remarks: OAL = 3.110 inches
105 Hodgdon H-870 67.0 3,255
Remarks: OAL = 3.105 inches
105 IMR IMR-4831 57.0 3,224
Remarks: OAL = 3.105 inches
105 IMR IMR-7828 59.0 3,202
Remarks: OAL = 3.105 inches
105 Hodgdon H-450 61.0 3,198
Remarks: OAL = 3.105 inches
105 Hodgdon H-4831 58.0 3,164
Remarks: OAL = 3.105 inches
105 Hodgdon H-4350 56.0 3,155
Remarks: OAL = 3.105 inches
105 Alliant RL-22 59.0 3,214
Remarks: OAL = 3.105 inches