Pressure Trace:50cal Reloder7 as single & 250ftx
Dec 9, 2011 15:31:22 GMT -5
Post by TGinPA on Dec 9, 2011 15:31:22 GMT -5
Pressure Trace:50cal Reloder7 as single & 250ftx sabotted.
In a recent thread, it was suggested that Reloder7, when compared with other powders, as a single, might produce superior velocity relative to peak pressure generation. Because I couldn’t find pressure data for RL7 for 50cal 250gr sabotted bullets, I thought it might be of value to trace some loads (68 & 72gr) using this powder as a single with sabotted 250ftx bullets. The traces are shown below. Of interest was the consistency and reproducibility of the curves, even with such a “light-for-caliber” 250gr bullet. Because QL predicts a relatively low in-barrel (~90%) burn efficiency with a 250 gr bullet at this load level, I had expected to see a greater variance between shots. Despite the low burn efficiency, this powder even with light bullets, may be capable of useful accuracy, though temp sensitivity may be an issue. Further, if one believes in the OBT theory, the 72gr load should be the more accurate of the two.
TG
Gage and Module Manufacturer = RSI Bluetooth model
Trigger Sensitivity = 5, Strain Gage Voltage =5.096 Gage Factor =2.11). For gage calibration, I used a 3 shot average peak pressure (35kpsi) RB traced for 5744 43gr, 250SST (sabotted) and then adjusted the calibration factor in my trace module to give that pressure when that specific load was traced. Rifle Stand: Caldwell Lead Sled. Altitude: 450 ft Chronograph: Chrony Alpha Model 8 ft from muzzle. (13 fps added to all recorded velocities to correct for distance of chrony from muzzle.)
Barrel Type: Savage 50cal Cal Muzzleloader Barrel OD = 1.03 in Barrel ID = .502
Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=.58in Bullet Diam.= .452in. Bullet Type = Hornady .452 250gr ftx unknurled.
Sabot: Harvester RCR.
Powder: Panel 1:Reloder7 68gr, 2shots. Panel 2: Reloder7 72gr. 3 shots. Panel 3 Overlay of panels 1 & 2 for comparison. Primer: Fed209A
Shot fm dirty barrel. This load seemed safe in my barrel under the test conditions but may not be so in other conditions.
In a recent thread, it was suggested that Reloder7, when compared with other powders, as a single, might produce superior velocity relative to peak pressure generation. Because I couldn’t find pressure data for RL7 for 50cal 250gr sabotted bullets, I thought it might be of value to trace some loads (68 & 72gr) using this powder as a single with sabotted 250ftx bullets. The traces are shown below. Of interest was the consistency and reproducibility of the curves, even with such a “light-for-caliber” 250gr bullet. Because QL predicts a relatively low in-barrel (~90%) burn efficiency with a 250 gr bullet at this load level, I had expected to see a greater variance between shots. Despite the low burn efficiency, this powder even with light bullets, may be capable of useful accuracy, though temp sensitivity may be an issue. Further, if one believes in the OBT theory, the 72gr load should be the more accurate of the two.
TG
Gage and Module Manufacturer = RSI Bluetooth model
Trigger Sensitivity = 5, Strain Gage Voltage =5.096 Gage Factor =2.11). For gage calibration, I used a 3 shot average peak pressure (35kpsi) RB traced for 5744 43gr, 250SST (sabotted) and then adjusted the calibration factor in my trace module to give that pressure when that specific load was traced. Rifle Stand: Caldwell Lead Sled. Altitude: 450 ft Chronograph: Chrony Alpha Model 8 ft from muzzle. (13 fps added to all recorded velocities to correct for distance of chrony from muzzle.)
Barrel Type: Savage 50cal Cal Muzzleloader Barrel OD = 1.03 in Barrel ID = .502
Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=.58in Bullet Diam.= .452in. Bullet Type = Hornady .452 250gr ftx unknurled.
Sabot: Harvester RCR.
Powder: Panel 1:Reloder7 68gr, 2shots. Panel 2: Reloder7 72gr. 3 shots. Panel 3 Overlay of panels 1 & 2 for comparison. Primer: Fed209A
Shot fm dirty barrel. This load seemed safe in my barrel under the test conditions but may not be so in other conditions.
??
