You may find what I see. Here’s a pic of the velocities of my .223 and I’ve highlighted two powders.
Red: 4007SSC. Top and middle will show you the approx 2700fps when the barrel is dirty with about 700 rounds of carbon in the barrel (carbon ring was cleaned regularly)
Then look at the bottom, after cleaning. Like you, the same load lost almost 100fps, as the 2700 fps dropped to just above 2600.
Two things are happening at the bottom. As the fouling grows, the speeds increase. Also, as the barrel warms, the velocities increase a bit too.
This heat effect is shown in green with another powder and this was with a dirty barrel. I didn’t write out the averages, but each 5 rounds is a group. The 2777 is a “1st round pop” when I started the 2nd batch of 10 shots.
The 1st round of a new string after a break can have funny values, so that’s why I didn’t include the 1st round of my groups in red at the bottom when I was calculating the averages.
I’m just observing behaviour. No conclusions on my end.
Red: 4007SSC. Top and middle will show you the approx 2700fps when the barrel is dirty with about 700 rounds of carbon in the barrel (carbon ring was cleaned regularly)
Then look at the bottom, after cleaning. Like you, the same load lost almost 100fps, as the 2700 fps dropped to just above 2600.
Two things are happening at the bottom. As the fouling grows, the speeds increase. Also, as the barrel warms, the velocities increase a bit too.
This heat effect is shown in green with another powder and this was with a dirty barrel. I didn’t write out the averages, but each 5 rounds is a group. The 2777 is a “1st round pop” when I started the 2nd batch of 10 shots.
The 1st round of a new string after a break can have funny values, so that’s why I didn’t include the 1st round of my groups in red at the bottom when I was calculating the averages.
I’m just observing behaviour. No conclusions on my end.
