Two Distinct Velocity Groups Today...?

[MNbogboy]

LabRadar

Yes, way to go if money isn't a problem.
The Magneto speed is very consistent and as accurate as the Labradar but it will affect POI and often group size.
On lighter barrels, especially with free recoil, impacts tend to move away from the bayonet position. Also the added weight often acts like a barrel "tuner" and actually tightens most groups. On heavy barrels these effects are less noticeable.

I use my magneto speed for determining initial powder charge velocities and for final velocity verification at load development completion.
Shooting with both the mag speed and optical at the start of a session can give you a "baseline" for the optical with the current light condition. Data still can be collected & adjusted during that session without the mag speed attached.
There definitely are options.
Good shooting.

 

[planetwaves]

Yes, way to go if money isn't a problem.
The Magneto speed is very consistent and as accurate as the Labradar but it will affect POI and often group size.
On lighter barrels, especially with free recoil, impacts tend to move away from the bayonet position. Also the added weight often acts like a barrel "tuner" and actually tightens most groups. On heavy barrels these effects are less noticeable.

I use my magneto speed for determining initial powder charge velocities and for final velocity verification at load development completion.
Shooting with both the mag speed and optical at the start of a session can give you a "baseline" for the optical with the current light condition. Data still can be collected & adjusted during that session without the mag speed attached.
There definitely are options.
Good shooting.

Yes, with magnetospeed, on my rifles the poi is about 5 or 6 inches high and there is more scatter. But the accuracy of FPS is great. So I work up a load first and then measure FPS, spread, etc.

 

[Canhunter35]

I've seen it where case lube dries, causing this effect. If you had waited a week on the stuff you loaded that day it may have been all the same velocity by then

 

[Canhunter35]

Yep! That's super frustrating. I've seen it and the obvious solution is to load all of them at the same time. One reason I've read or been told that explains the phenomenon has to do with how soon after resizing you load and seat bullets. The theory goes that after a few days the brass gets a chance to "set". I'm really not sure if there's any science behind this but I will admit that loading bullets days after sizing and everything after was more consistent in velocity than those loaded immediately after sizing compared to later. Outside of some weird brass voodoo a more logical answer to me is humidity. Since water is incompressible, higher or lower air humidity when loading could create pressure differences. I have not done any kind of testing with this but since I do not have a climate controlled clinical lab area to load so I try to be conscious of those unusually high humidity days. Just some food for thought here. Would love to hear if others have any thoughts to this theory.

It's because the lube dries. If u load right after resizing, the lube is wet and sticks to bullets, really holding them that you cannot even pull them. I like to wait a week after sizing