Heads Up - Bullseye Charge Weights

[rbwillnj]

I have a collection of Star BE powder slides all marked on their sides with the weight of Bullseye powder that the slide actually dropped.  It has been my experience for the past 10 years or so, since I started reloading with Stars, that BE powder slides always drop 0.2-0.3 grains more BE than marked on the slide...........until now.

I just bought an 8 pounder of Bullseye, and now my BE powder slides are giving me the exact charge Star stamped on the slide.

[fc60]

Greetings,

Powder lots do vary. I have four different lots of Bullseye from the 1960's to present. I always use a chronograph when changing powder lots and retest my existing loads for accuracy.

Cheers,

Dave

[rbwillnj]

I do check charge weights when I switch from one container to another, and some times in between.  Though it might be a good idea, I don't crono each batch of powder, and I doubt if many do.....not for pistol anyway.

My point is, as long as I have been checking drop weights, a BE powder slide has never dropped the stamped weight,  it has always been 0.2-0 3 grains higher than the stamped weight.  Others I have talked to have said the same..   For the first time, I have a batch of powder that drops the weight stamped on the slide. 

For example, I have always ....always used a BE 3.7 slide to drop 4.1 grains of Bullseye for my wad gun.  Now I'm using a BE 4.1 slide.   That's a pretty big difference.  I'm not complaining, just making an observation, and maybe a suggestion that if your not doing it, folks should check their charge weights when they change batches of powder.

[NYKenn]

I check the drops each time I start reloading even with same powder still in tube from previous efforts.  I have noticed slight deviations, but usually + or - .1. Seldom more or less than that.

[tguntrader]

, I just got back from range. shot my clark custom for the first time in a 2 mo. on my bar it said it drops 2.7 mine  always drops about 2.9 like you was said when  i got my loads ready last night i took some old powder and new mixed it in one container It drop 2.7 like the bar said. could be the old powder was stronger?      hope this helps  tguntrader

[Lifetyme]

Friends and I are easily entertained so we have discussed this situation at length.  Powder volume is going to remain unchanged while moisture content will change, which seems to me will be the reason for the weight variance.  What effect the moisture content has on "strength", I cannot say.

One of the reasons I like the Star machine's fixed powder bars is that I get a consistent volume of powder thrown each charge.  I will weigh occasionally and have not seen any significant velocity difference when chronographing lots whose weight varies from the last.  I talked to an Alliant rep at SHOT and he told me that extremely old lots they have in frozen storage don't differ in "strength" from current production.

FWIW.

Bob

[rbwillnj]

I'm sure that Alliant and others work very hard to maintain a consistent strength (or cup pressure) from lot to lot.  I would be surprised if they measure that strength based on volume rather than weight.   I think there is a reason why we talk about charge weights rather than charge volumes.   

Moisture certainly could be the  reason for the variations in the drop weight from a given powder slide.   It would be interesting to see if a 2.9 grain charge from a 2.7 BE powder slide gives the same results as a 2.7 grain charge from the same powder slide.

When I first started shooting Bullseye, all the old timers talked about 3.5 grains of Bullseye under a 200 grain LSWC.   I found in my Ransom Rest testing that that load wasn't all that great.   I found that 4.0-4.1 grains of Bullseye gave me the best accuracy.  It may just be my gun, but the funny thing is that my 3.5 BE powder slide was drops a 3.8 tp 3.9 grain charge......most of the time.

[Hank Woll]

does someone have a location or member that i can contact to get slides that throw more than 3.5 gr of bullseye and even more than that for powder such as unique and red dot??-thanks hank woll

[rbwillnj]

Hank,  PM sent.

[rbwillnj]

Related to this topic, I found the following on the Lee website.

Quote: VMD Explanation

The Volume Measured Density (VMD) of a powder is the volume in cc's (cubic centimeter) that one grain of powder occupies. This can be used to calculate the dipper, disk cavity or powder measure setting required to obtain a desired weight of powder.

Example:

 If a powder has a VMD of  .1064 , and the desired charge weight is  4 grains,

4 x .1064 = .4256, or . 43 cc's

 This would translate to the  .3cc dipper, (because the next larger one is beyond.43 ccs) the  .43cc disk cavity, and a  .43cc setting on the Perfect powder measure.

 Lee attempts to keep a current list of newer powders and their VMDs on their "Instructions" page of the Lee Precision website.

Determine a VMD on your own

 Using any setting on your powder measure (preferably a whole number), drop a charge of the powder you wish to determine the VMD for. Weigh the charge. Divide the measure setting you used to drop the charge by the weight of the charge. The result is the volume (cc) of a single grain of powder (VMD)

 CC setting (powder measure setting)
 --------------------------------------- = VMD (volume in cc's for 1 grain)
 Weight of the sample

 It is very important that you repeat this process with any new container of the same powder because the powder companies allow themselves a 16% tolerance between batches. This can result in over charging if you work from the same setting and the next container of powder you get is more dense.     End Quote

16% tolerance seems huge.  I wonder if that is really true.   

[Star73]

This is a bit late for this thread BUT; a few yrs ago I started a new 4# of BE. My SP is to load a small no of rds w/ my std .45 WC charge of 4.15 (check drop wt 1st). The load were very weak, smoked, would not cycle dependably. The lot required 4.5 for reliability.

I called Alliant and they said results were well within their spec but did not say what that spec was. Over the yrs I used 3 bushings for the variations. They are 4.0, 4.15, & 4.25. Excepting the lot prev described they have covered the variations.

Hope this might be of use to someone?

Ron