Tag: pumps

October 26, 2023 – How Many Pumps for Accuracy

Hopefully, my zeal for experimentation and data translates into interest. I know that not everybody is like me. But, I get excited when people are excited about what they are doing. It really doesn’t matter what the topic is, I find it fascinating when people are into their thing. I may not want to do it, but I enjoy the enthusiasm.

The truth is, I wrote the article “I Hate Pumping” a few weeks ago prematurely. It was always my plan to test accuracy of BBs based on the number of pumps. I should have written after I collected all of the data first but I was in a little bit of a funk. I was getting ready to hunting and was suffering a little bit of brain fatigue. I needed something on the spot and I didn’t have time to do all the work.

My creativity seems to go in spurts. Right now, I am flush with ideas and time is getting a little less constraining. Now that the sun is going down with some evening left, I have time to read, think and tinker in the evening whereas in the summer it seems like it is go until you drop. I have several weeks of topics (that I think are good) in the queue. So, I want to close the loop on this testing for you.

Let me start with what I was trying to accomplish. Using the Crossman 1000 and shooting BBs, what does the number of pumps do to velocity? I did a series on pellets many months ago but I wanted to use BB’s this time because my preferred rifle, the Crossman Optimus only shoots pellets and I have a whole bunch of BBs. After understanding the pump to energy curve and knowing how many pumps would be adequate energy to dispatch pests, I wondered if this was even an accurate platform with BBs.

I found out that pumping the maximum twelve pumps is a chore but it was also pretty wild after the initial five attempts. To boil it all down, is it even worth it to shoot BBs? Looking at the picture, I think that you can see nine pumps is a significant improvement in accuracy over 12, it looks like seven is slightly better, five looks pretty dialed in and three starts to wander again.

This is good news. If the results would have all been like twelve pumps, I would have given up. Five is also a far cry from twelve pumps in the effort department. Looking at the energy data, I am not sure the energy is adequate for pests at five pumps, but that is OK, BBs are far cheaper to shoot if we are just talking about practice and trigger control and I have a lot of them around. The most important thing for practice is that it will hit where you aim.

Of course, now I will not leave things here. I am going to try a new series with my son’s Crossman 760. I did a baseline test months ago with pellets and found that rifle to be vastly inferior to the potential velocity. Ten pumps (the max) was equal to about four pumps on the Crossman 1000. What I am now trying to establish is that is it the velocity that stabilized the BB or is it rifle specific?

That being said, expect another one of these with a new set of data. This time, I promise that I will wait until I have everything completed. But like I said above, I need to do a better job closing the loop with subjects that I introduce. Maybe I should introduce a new category like ‘Results’ to share my conclusion. That will keep me more honest when using it and then I can write the post in a more scientific fashion. I will think on that.

End Your Programming Routine: Based on my results, BBs can be accurate without needing Popeye’s arms. That being said, not all tools are best suited for every job. Where I have settled is that I should be able to adequately shoot BBs with five pumps for practice. Stayed tuned for another analysis on potentially why five pumps is the best.

September 8, 2022 – ‘Tacticool’ Thursday

I was reading the literature to see what to expect with the Crossman Legacy 1000. I didn’t actually realize that it is a twelve pump maximum, not a ten pump. Let me tell you, that is a heck of a lot of pumping. In this experiment, I am measuring the velocity of each number of pumps to determine if it at what point is the work of pumping diminishing.

123456
1219399497565618657
2223400504562615659
3226392498568617662
4231400502561616666
5226398493564622664
6220402494568618664
7220396500566611663
8225389499563618669
9232397502559623665
10218398497567613668
224 +/-15397 +/- 12499 +/- 11564 +/- 10617 +/- 11664 +/- 11
values in fps
789101112
1701726752775798812
2700732755781796808
3698727751779799803
4688730760781793802
5695729758771790810
6695729758772797803
7699725763774798811
8696728758773798807
9695724757777795809
10693723757777789811
696 +/- 11727 +/- 8757 +/- 11776 +/- 11795 +/- 11808 +/- 11
values in fps

One thing from the data that is very pleasing is that repeatability is extremely consistent. It is interesting that the standard deviation is very constant throughout the experiment. That means that the rifle is operating the same as well as the ammunition. This data was obtained using the Crossman Wadcutter pellet (7.4 grains) at muzzle velocity.

There is math to actually determine the optimum pump versus velocity return. It involves calculus, so not so simple and therefore I won’t put it in here. Without actually showing the math, I am going to give the answer: two pumps. I have graphed the data to make it much easier to see. The math says that the inflection point of the curve

Despite the fact that two pumps is the optimum efficiency, we probably want to take advantage of the more available velocity. So, this becomes a subjective decision. In my view, the optimum maximum is eight pumps. 727 fps is 90% of the maximum 808 fps which would save 4 additional pumps.

Going back to my point of aim, point of impact discussion a couple of weeks ago the shooter really needs to settle on goals because simply pumping less or changing ammunition can relate this whole conversation moot. What I am implying is missing the target. When shooting at something the size of a squirrel head, an inch makes a difference between hit or miss.

To boil this all down, what I am suggesting is knowing the performance curve allows the shooter to select the desired outcome and subsequently sight in accordingly. Once that is done, then the shooter needs to stick with (or at least check the outcome) of variable changes.

End Your Programming Routine: I promise, this is the last concurrent week of this testing. Next week will be something new. This experiment actually took some work because of all the pumping and there was a lot of math. I am very surprised at how well this curve fit into a logarithmic function. I suppose that means that physics and math really does describe the world. I have always said that math is only interesting if you care about the results and what it says. In this case, I do care about the results, but it is nice to see that math validates how everything works.