Powder measure variation

[ArkansasFatboy]

Guys I am new to reloading.Well tonight I finished my first rounds.But my question is while using my RCBS piggyback powder measure I would weigh I load at 5gr the next might be 5.1 and the next might be 4.9 but this was all it would vary is this normal? I was loading .45acp 230gr lead cast bullets with 5gr unique powder are these variations exceptable:banghead:

 

[Lone_Gunman]

Thats the same kind of variation I get with the Lee Pro-Auto Disk powder measure system. I think there is at least that much variation in factory ammo also. I base this on the fact that the standard deviation of the velocities of my handloaded ammo is the same or better than factory ammo.

Also, I have found Unique does not meter as consistently as smaller ball powders.

 

[Steve C]

1/10th grain + or - is acceptable with a pistol load and is common with flake powders like Unique. You can minimize the variation by settling the powder in the hopper and the tube with a few raps on the measure before each throw.

Ball powders usually meter very well in the RCBS type powder measure. W231 is very consistant in the throws to the point its not measurable on a powder scale.

 

[Idano]

I totally agree that 1/10th of grain variance is very acceptable. It is that variance is why you shouldn't be loading max loads in a progressive IMO. When I am loading progressive I usually try to find a load that works well with my gun, fills the case at least half way and has a .5 grain safety margin either way. I can't always achieve that goal but try to get as close as possible.

 

[Walkalong]

When they can build a cheap measure that throws less than .1 grain variation it will dominate the market...Normal.... You'll find with some powders it's worse.

 

[Cloudpeak]

I quit using Unique because of variations with my powder measure. My thought was that a few tenths of a grain variation wasn't significant if you were talking charges of 20-50 grains of powder but might be at lower charge rates.

I worked up loads for my 40S&W and 45 ACP using Power Pistol and W231. Both of these powders measure very accurately in both of my powder measures (One Pacific that I use for working up loads and the Hornady LNL on my LNL Progressive.)

Today's project is to shoot for group some loads of 45 200gr SWC loaded with Clays. I weigh each load when I'm working up loads and I noticed the Clays has a variation of .2 to .3 of a grain on occasion. (Pacific measure, I haven't thrown any Clays through the Hornady measure, yet.) Clays is more "flakey" than Unique, IMO.

Cloudpeak

 

[Walkalong]

Ditto on Clays, with light charges I was getting very erratic charges thrown with my Redding 10X. I forget offhand which wieght it seetled down at and became consistent.

 

[cracked butt]

I would weigh I load at 5gr the next might be 5.1 and the next might be 4.9 but this was all it would vary is this normal?

If that is what its throwing, you are within the accuracy range of your scale unless you have a very expensive analytical scale- the range you are getting is about as good as its going to get, and I wouldn't worry about it a bit.

 

[Ares45]

Your powder measure measures powder by volume, not weight so it's inherently less accurate. Plus or minus 1/10th is within acceptable limits. Run with it unless you are loading max charges.

 

[cracked butt]

Your powder measure measures powder by volume, not weight so it's inherently less accurate.

Not true.
A given volume of powder will always be same volume, weight per given volume will fluctuate from one lot of powder to the next, or a measure of powder from a single can will fluctuate over time due to absorbing moisture from the air or drying out.

Example: you measure 2 cubic centimeters of powder from a can of IMR ABCD and 2CCs of powder from a 2nd lot of IMR ABCD, they will weigh differently but will be the same amount of powder.

 

[Walkalong]

Benchrest shooters don't measure (wiegh) powder charges. We throw them with our measures. Consistent volume is more important than wieght.

 

[brickeyee]

Always use a baffle with a volumetric measure to unload the weight pf the powder reservoir from the metering chamber.