I've read here and elsewhere about fine tuning a load for maximum accuracy by varying the charge weight by as little as 0.3gr either way, implying a definite sensitivity to charge weight at the third-of-a-grain level.

When using my powder measure (it's the Lee Perfect Measure that came with the kit), I get thrown charges that vary by as much as +/- 0.7gr. This has been the case with H4831SC, RL15, and Win 760.

I've not used the measure to actually load cases yet because of this. So, a couple of questions:

Is this typical for powder measures to vary that much, or is it just a phenomenon of the Lee product?

Is a charge-to-charge variation of +/- 0.7 grs not worth worrying about? It would seem to me that it would be. So far I have been weighing every charge and I can see the allure of using a powder measure to simplify the process, but if powder measures are this "unstable" I don't think I want to go there.

Any thoughts would be appreciated.

Thanks

quote:

Is this typical for powder measures to vary that much, or is it just a phenomenon of the Lee product?

Yes it is but not with ball powders......many powder measures will drop ball powders +/- .1 grain

quote:

Is a charge-to-charge variation of +/- 0.7 grs not worth worrying about? I

charge to charge variation of +/- 1% IMO isn't significant for accuracy but may be significant if the mean load your shooting is very hot.....in which case one should weigh every load to .1 grain.

A single grain of powder can increase pressures of a (book) max load by as much as 3,000 PSI or so.....so be careful when loading to the "max"

If you're a benchrest shooter then accuracy is probably affected in some manner that a hunter might not discover for a while and it's insignificant.

With the powders you list, a high-quality measure will give somewhat more consistent drops -- on the order of + or - .2 grains.

While .7 grains is of some concern if your charge weight is, say, 25 grains, it is of very little concern if your charge is say, 60 grains. I suspect that most factory loads would be proud to have a charge variation of less than 2%.

The solution (assuming you don't want to spend another $100 for a new measure) is to drop your charges into your scale pan (with the measure set a little on the light side), then use a trickler to add the final half-grain or so to the charge. This takes a little time, but is advisable with any powder measure when using one of the coarse powders like conventional 4831 or something similar that meters with difficulty.

sometimes it makes a big difference in what size cases you are loading to. are you loading a 223 or a 300 win. mag... 1 grain difference in a 223 might make a big difference in accurace. but 1 grin say in a 300 win. mag you may not see any change at all.

I'm loading for 270Win and 375H&H... so it sounds like this kind of variation is not that big a deal as long as I am not in danger of sneaking past the max load point...

Thanks
Mike

quote:

Originally posted by mrjulian_1970:
I'm loading for 270Win and 375H&H... so it sounds like this kind of variation is not that big a deal as long as I am not in danger of sneaking past the max load point...

Thanks
Mike

It's a good idea to throw 20 charges and weigh them one at a time and record them so you have a handle on the actual variance. You might be surprised at the actual variance if you do this and you should also be able to draw a bell shaped curve of the results.

However when loading for cases with 60 grains and more of powder one should be able to throw charges and have fully adequate loads for hunting.

That said.....it takes very little extra time to weigh and trickle every load for sake of a clear conscious.

I agree with everything said here.

Just note, however, that some precision shooters think more of volumetric charges than of weighed charges. In other words, they would rather have ten cartridges charged with identical volumetric charges that vary a little in weight than ten with identical weight charges that vary a little in volume.

The bottom line is that your .270 and .375 probably won't know the difference whether they are fed dropped or weighed charges.

Dropping the charge first into the scale pan does allow you to check to see that something is not amiss, even if you then directly dump it into the powder funnel without adjusting for small variations.

My practice is never to bother with weighing ball powder charges; to check the weight on short-grained stick powders like 4895 or the RL series; and to drop-then-trickle on coarse powders like 4350, etc. I use a Redding Master measure (35 years old) which is said to be one of the more consistent on the market. Your Lee probably won't be quite as close, but it will still be fine with most of the fine-grained powders.

How much variation is in the scale?

quote:

Originally posted by mrjulian_1970:
I'm loading for 270Win and 375H&H... so it sounds like this kind of variation is not that big a deal as long as I am not in danger of sneaking past the max load point...

Thanks
Mike

If I'm spending the time play with seating depth,trimming case,sizing,tumbling, priming etc to get the cases right what's another step in weighting,trickle powder to get that right.

All the years I've been reloading I have never seen one load like 50.5 gr +/- .07gr. We know scales like the RCBS 1500 can be +/- 0.1gr even their 10-10 beam scale is accurate to 0.1 .gr