Pressure Traces: 3 duplexes with Reloder 7
Jun 23, 2011 14:53:21 GMT -5
Post by TGinPA on Jun 23, 2011 14:53:21 GMT -5
Pressure Traces: 3 duplexes with Reloder 7
Reloder 7 possesses a burn rate theoretically suitable for use in duplex loads with 195-200gr sabotted bullets. As a double-based powder, when compared to single-based powders with comparable burn rates, it’s ignition might also be less affected by low temperatures. Richard’s load data base lists only 3 RL7 containing duplex loads with velocity data and he traced N110/RL7 duplex loads in weeks 1, 4 and 7 in his tracing data. To extend experience with duplexing Reloder 7, I traced loads with three boosters: XMP5744, SR4759 and N110 with 200gr sabotted bullets, all at velocities exceeding 2700fps. All duplex loads gave similar traces, IMO, suggesting that any of these three boosters would work as part of a duplex load with RL7 for sabotted bullets in this velocity range. Because these traces were obtained in relatively warm conditions, it is probable that powder loads might be tweaked upward in cooler conditions, further increasing velocity without sabot disruption. Pairing RL7 with a double-based booster (ie XMP5744) did not seem to grossly alter pressure-velocity relationships or pressure trace shape when compared to loads with the other two nitrocellulose-based boosters. Also of interest was the performance of XMP5744 in this application. In my experience, when used as a booster, this powder often leaves a bore residue of unburnt powder grains. In this application, this was not apparent.
TG
Gage and Module Manufacturer = RSI USB model
Trigger Sensitivity = 2, Strain Gage Voltage =4.9 Gage Factor =2.1 PSI Correction Factor: 0
Barrel Temp = 67-69 degrees F. measured at the sensor (IR). 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: PacNor .45 Cal Muzzleloader Barrel OD = 1.06in. Barrel ID = .452in.
Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=1.1in. Bullet Diam.= .40in.
Type = Hornady 40 cal. Bullet weight = 200gr. ,unknurled. Sabot: Harvester Smooth Blue Primer: Fed 209A
Powder: Panel 1: N110/RL7 16/41gr.
Panel 2: SR4759/RL7 10/55gr.
Panel 3: XMP5744/RL7 20/45gr
Shot fm. dirty barrel. These loads seemed safe in my barrel under the test conditions but may not be so in other conditions.
Reloder 7 possesses a burn rate theoretically suitable for use in duplex loads with 195-200gr sabotted bullets. As a double-based powder, when compared to single-based powders with comparable burn rates, it’s ignition might also be less affected by low temperatures. Richard’s load data base lists only 3 RL7 containing duplex loads with velocity data and he traced N110/RL7 duplex loads in weeks 1, 4 and 7 in his tracing data. To extend experience with duplexing Reloder 7, I traced loads with three boosters: XMP5744, SR4759 and N110 with 200gr sabotted bullets, all at velocities exceeding 2700fps. All duplex loads gave similar traces, IMO, suggesting that any of these three boosters would work as part of a duplex load with RL7 for sabotted bullets in this velocity range. Because these traces were obtained in relatively warm conditions, it is probable that powder loads might be tweaked upward in cooler conditions, further increasing velocity without sabot disruption. Pairing RL7 with a double-based booster (ie XMP5744) did not seem to grossly alter pressure-velocity relationships or pressure trace shape when compared to loads with the other two nitrocellulose-based boosters. Also of interest was the performance of XMP5744 in this application. In my experience, when used as a booster, this powder often leaves a bore residue of unburnt powder grains. In this application, this was not apparent.
TG
Gage and Module Manufacturer = RSI USB model
Trigger Sensitivity = 2, Strain Gage Voltage =4.9 Gage Factor =2.1 PSI Correction Factor: 0
Barrel Temp = 67-69 degrees F. measured at the sensor (IR). 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: PacNor .45 Cal Muzzleloader Barrel OD = 1.06in. Barrel ID = .452in.
Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=1.1in. Bullet Diam.= .40in.
Type = Hornady 40 cal. Bullet weight = 200gr. ,unknurled. Sabot: Harvester Smooth Blue Primer: Fed 209A
Powder: Panel 1: N110/RL7 16/41gr.
Panel 2: SR4759/RL7 10/55gr.
Panel 3: XMP5744/RL7 20/45gr
Shot fm. dirty barrel. These loads seemed safe in my barrel under the test conditions but may not be so in other conditions.
?