TRG65 Posted July 18, 2003 Share Posted July 18, 2003 When I was recently chronographing some loads because I was testing spring effect, I found they were running about 16fps lower than I have in my records (more than 2 SD's). The load that I thought I was using is 2.85grs vv310 under a 147 zero JHP and a win srp. I hadn't refilled my powder measure before starting to load this last batch. The powder level started below the baffle. I have found in the past that I can still get about 150 rounds before the powder runs totally out so I wasn't concerned. Then I chroned them. Link to comment Share on other sites More sharing options...
Duane Thomas Posted July 18, 2003 Share Posted July 18, 2003 I wouldn't sweat 16 fps. In the overall scheme of things, that's no difference at all. The phase of the moon could have been different than the last time you chronoed. "2.85 grains." Man, where did you find a scale that can measure the hundredths of a grain? I hope you don't really think you're getting exactly that on every throw of the powder charge. Link to comment Share on other sites More sharing options...
EricW Posted July 18, 2003 Share Posted July 18, 2003 If you look at the bottom of the powder measure, you'll see a baffle. That baffle essesntially eliminates (mostly) the weight of the column of the powder above it. You really shouldn't see much powder charge variation as long as you're running off the top 1/3 of the powder measure. FWIW, I never load with the powder level closer than about 2" to the top of the baffle. Link to comment Share on other sites More sharing options...
TRG65 Posted July 18, 2003 Author Share Posted July 18, 2003 All I did was averaged 10 or 20 throws and the average was 2.85, and no I don't think I'm really getting exactly 2.85 grs. Another time I averaged I got 2.83; the average does stay pretty close. The difference in 16 fps in a 127-128 pf load with a 147grain 9mm bullet is a 124-125 pf load. So one time I chronoed and I was just fine on pf and the next time I'm barely there. SD is very tight so I was not expecting to see any drop more than about 5-6 fps. So if the baffle eliminates the column weight, why do you keep the powder measure so full? Link to comment Share on other sites More sharing options...
EricW Posted July 18, 2003 Share Posted July 18, 2003 So if the baffle eliminates the column weight, why do you keep the powder measure so full? 2" over the baffle is about 1/3 full. That's not very full in my way of thinking. I never start a loading session without a 90% full measure - primarily because I rarely start a reloading session with the intent of doing less than 500 to 1000 rounds. I keep it that full to: A) ensure a consistent flow of powder to the measure and... 47.2) not run out of powder and load dud rounds. BTW, 2.9 grains is not a lot of powder. Dillon measures are generally regarded accurate to +/- 0.1 grain. The easy way to gain consistency in your load - if you're *really* worried about it (which I wouldn't be) - is to switch to a slower powder that requires a higher charge weight. That way, the inaccuracy will be distributed across a greater charge, resulting in less velocity variation. But DT is correct in that 16fps is nothing to worry about. ----------------- Oops, I had my fractions inverted in my head. I should have said that you shouldn't see any charge variations as long as you're running off a 1/4 to 1/3 full or fuller powder measure. Link to comment Share on other sites More sharing options...
George Posted July 18, 2003 Share Posted July 18, 2003 I have always tried to keep the powder level over a couple inches in all my Dillon measures (all on a 550). I recently wanted to run a batch of powder out, so I went to the absolute bottom of the measure and here is what I found out. As long as there is enough powder to fill the funnel shaped bottom of the measure, the charges throw the same as a 1/4, 1/2, or full measure. I didn't believe it but even the last charge I threw with barely an 1/8" of powder above the charge bar opening weighed the same as when I set the measure (3/4 full) at the start of the loading session. BTW, this was with ball powder (ww 748). Make of it what you will, but it looks like the Dillon measures are real good shjt. I will still stay away from the bottom 1/4 of the tank if possible, but I won't be afraid of it anymore. Regards, Link to comment Share on other sites More sharing options...
kahana Posted July 19, 2003 Share Posted July 19, 2003 George, I have a Dillon 650 and I tried the same thing finishing out some powder.......... Same results as you and I agree with your conclusion. laters, gr Link to comment Share on other sites More sharing options...
Flexmoney Posted July 19, 2003 Share Posted July 19, 2003 Seth, Did your last chrono session include both spring rates? If you are just comparing to your past record...well, there are lots of things that could cause a 16fps variation. (heat and humidity...or lack there of...comes to mind) Link to comment Share on other sites More sharing options...
kevin c Posted July 19, 2003 Share Posted July 19, 2003 Some tubular grained powders, like the VV I use in limited, meter extremely well, and I find that "Its good to the last drop". Some flake powders, especially the older ones, perhaps because of the shape of the powder grain, or mebbe the lower density, don't meter for me nearly as well as the powder measure goes less than a third full. The flake powders also take longer (more test charges thrown, or more tapping on the side of the hopper) to settle into a consistent charge per throw. Link to comment Share on other sites More sharing options...
TRG65 Posted July 19, 2003 Author Share Posted July 19, 2003 The chrono sessions comparing springs were about 12 hours apart, just because by the time I had the batch loaded I didn't want to shoot the whole 100 rounds. It was actually a magazine function test. The previous batch that was the higher pf was from late June. I do all my chronoing and testing in my basement with an indoor lighting setup; the humidity and temperature are pretty constent year round. While I don't think there was a significant variation in enviromental or lighting conditions, I'm going to try a pared down version of the spring test Brian suggested so I have more than one set of data. But I'm going to fill the powder hopper. Link to comment Share on other sites More sharing options...
SAB Posted August 17, 2003 Share Posted August 17, 2003 When I first got my 1050, I tested the power measure's consistency by weighing 20 throws when nearly full and again when nearly empty and found no significant difference, but the test was done on a 223REM load of about 25gr, not a pistol load (large powder bar in the measure). SAB Link to comment Share on other sites More sharing options...
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