I was testing Blue Dot in some .41 Colt reloads today and on the last five rounds noticed if I flip the muzzle upward before shooting I got 745, 769 & 791 fps and when I dropped it toward the ground before shooting got 651 & 607 fps. These loads were all with 7.0gr Blue Dot. Has anyone else noticed this?
Blue Dot position sensitive?
- Thread starter 41 Colt
- Start date
- Location
- In the middle of gopher country
I have never used BD in hangun.
However, I have noticed in rifles that the velocity changes a little. The change is in the order of 50 fps in the 2800 fps range.
However, I have noticed in rifles that the velocity changes a little. The change is in the order of 50 fps in the 2800 fps range.
Jordan Smith
CGN Ultra frequent flyer
- Location
- Calgary, AB
I've used BD in several rifle cartridges for reduced loads, and the average velocities, SD, and ES are among the lowest of any load or powder I've ever used. This holds true across the board for the half dozen, or so, rifles I've used it in from .22-250 to .338WM. I'm typically using between 15 and 25gr of powder, and position in the case seems to be irrelevant, and very insensitive with regards to ignition and velocity results.
How full is your case with that charge? If the powder charge is filling the usable cartridge volume by less than 2/3 you can usually expect some effect on velocity due to powder position in these small capacity low pressure pistol cartridges. Loading antique revolver cartridges is a different game altogether than reduced loads in rifle cartridges.
Jordan Smith
CGN Ultra frequent flyer
- Location
- Calgary, AB
I'm not sure if you were responding to me or not, but my cases are typically about 20% full. I throw a powder charge and seat a bullet, one at a time, in order to avoid double-charging a case. BD is very position insensitive in this application, IME.
I don't doubt your results but we're talking about 2 different things here; what may be true in your rifle cartridge is not necessarily so in pistol cartridge. Powders have different burn characterisitics at different pressures, and this would seem to be an example of that.
My experience with BD in short antique low pressure cases like the .455 webley is that they are position sensitive, just like the original poster found in his .41 colt loads.
These old pistol cartridges are loaded to 10-12K psi (1/2 the pressure of a reduced rifle load) and are fired out of a 4 inch barrel as opposed to a 20inch or longer rifle barrel. It's not that surprising they react differently.
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75% is pretty good case usage. I've never been abe to get as consistent velocity results from BD in pistols as i do with Unique or Bullseye. I kind of think that BD is right on the edge of being too slow for reliable repeatable ignition in a low pressure pistol cartridge.
Jordan Smith
CGN Ultra frequent flyer
- Location
- Calgary, AB
Agreed. That's why I said "in this application"
I just put it out there for informational purposes...
