A fellow member of these forum requested i fill the powder chamber of the pictured 223 breech plug with 777 powder, finish the load with 80g of BH209, and clock it. He requested large rifle primer be used, and wanted me to compare this duplex load to a full load of BH209. So i did.






This morning, i set a target out at 47 yard, and set the clock at 16 yard. The bullet use in all testing was the 300g Deep Curl in a short black sabot.

The first three shots i took with 85g of BH209, and the clock read

1679 fps
1604
1604

The average of these is 1629 fps, which calculates to a muzzle velocity of 1675 fps.


Then i shot 3 shots using the duplex load, with 5g of 777 and 80g of BH. They clocked at

1515 fps
1563
1555

These average to 1544 fps, which calculates to a muzzle velocity of 1586 fps.





Then i shot 3 85g loads of 777. It wasn't necessary to swab between shots. They clocked

1670 fps
1635
1616

Which averaged to 1640 fps, and calculates to a muzzle velocity of 1686 fps.

Then i shot 3 85g loads of BH again. The first bullet went down hard because it was following 3 777 loads, but i managed to seat the bullet without a lot of pain. They clocked

1638 fps
1685
1598

Which averaged to 1640 fps, which was exactly what the 777 was, and of course the same 1686 fps muzzle velocity.





It seemed to me there was a large spread in the velocities. I figured it was my doing, because i wasn't being consistent enough in my measuring using the TC U view measure. I tried as hard as i could, to be consistent. To check and see if this was true, i shot 3 shots of 110g BH that had been measured by the Redding 3BR powder measure. These shots clocked at

1787 fps
1796
1796

These 3 speeds average to 1793 fps, which calculates to 1843 fps at the muzzle.




After shooting all these shots, only 2 groups are still visible on the target. The top 3 were made by the 85g 777 load; the next 3 down were made by the duplex load.