Saturday, November 28, 2009

Partially Crimped Hornady TAP/FPD...

12 Gauge 00 Buck.

I haven't run across this before, the crimp is not fully closed. I found it when I was arming the Strategic Twelve Gauge of DoomTM --more on that later. I plan to disassemble this one and attempt to find the root cause. Perhaps wad not seated properly, perhaps double charge of shot, etc... If I puzzle it out, will relate here.

I emptied the shot from the improperly crimped round and counted eight pellets. After removing the shot, I noticed that the wad was inserted into the case unevenly. After pressing it into place, I reloaded the shot and was able to press the crimp closed.

I chose to weigh this shell with its four box mates and the results are as follows...
--I have no idea why there is such a large gap between this text and the data tables and between each data table. My html is mighty dated and rusty, but the following should have worked pretty well - any suggestions will be greatly appreciated. Apologies for the large gaps in the post, it looks dreadful, but I do not know how to fix it and the searches so far have yielded no answers.

RoundCrimp Status#1 (g)#2 (g)#3 (g)Avg (g)Ind Stdv

The weighing cycle was Round one to five repeated three times and the values recorded. The Avg (g) is the average of #1 (g) to #3 (g) for each round. The Avg (g) is the MS Excel function average and the Ind Stdv is the MS Excel function stdevp, yes, I know that a population of three is about useless in talking of standard deviations. I used it to show that, for the three measurements taken, the deviation is essentially the same and therefore the instrument yields repeatable results. I have certified standard weights that I could have used to prove this, but for the purposes of this blog... Lab Suiter, please... I am just not going there.

The improperly crimped one certainly seems to weigh more than its brethren, but this one has been handled (by me) to a much larger extent than the rest and it is possible that I have altered the mass inadvertently by too much touching. And maybe, it just weighs a bit more. The point being that I did not handle each of these with tongs or gloves.

The point of this exercise was to determine whether this shell might have been double charged. I believe, reviewing the data at hand, that there is little to no danger of this possibility.

Pop StdvPop Avg+3 stdev-3 stdev
Pro Cri StdvPro Cri Avg+3 stdev-3 stdev

The Pop Stdv is the MS Excel function stdevp used on the entire data set. The Pop Avg is the MS Excel function average used on the entire data set. +3 and -3 stdev is the Avg +/- 3 stdv. The Pro Cri Stdv is the MS Excel function stdevp used on the properly crimped data set and the Pro Cri Avg is the MS Excel function average used on the properly crimped data set.

Data gathered using an Ohaus (uncalibrated since move) Adventurer (Model AR-3130). Left uncalibrated as the actual value was unimportant, the difference in each member of the population was.

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