Tag: accuracy

October 26, 2023 – How Many Pumps for Accuracy

October 26, 2023 /

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 21, 2023 – Heavy For Caliber

September 21, 2023 /

You know that I am a scientist and that I like to do things just for the heck of it. An experiment if you like. Well, this is an experiment. I found some .177 pellets online that I purchased a few years ago. They are 16.4 grains in weight which would be double the normal weight of run-of-the mill air rifle pellet. For reference, that would be in the 5-9 grain range.

In my quest to find the best pest elimination combination i.e. energy, I thought that I would give these things a try. Because of the weight of these pellets, they are not able to achieve the velocity of the lighter pellets and therefore, they make less energy than the other pellets I have tested. But what about accuracy?

I was reluctant to shoot these because the label said for PCP (Pneumatically Charged Pellet) rifles only. These are rifles that are filled with SCUBA tanks or air compressors like Lewis and Clark used (did you know that?). PCP rifles are becoming a thing because they are not considered firearms and are made all the way up to 50 caliber making them suitable for hunting large game.

When I put these pellets in my break barrel Crossman, they stuck out about 1/16″ of an inch of the chamber. A normal lead pellet would compress to be forced all the way into the chamber. This was my hesitation to trying them in the first place. But I closed the barrel anyway and gave it a shot (literally). It worked. OK, now I am going to zero the scope. And here is where the problem was manifested.

The picture above shows 10 and 50 shots with no scope changes at ten yards; the rifle is on a rest. My rifle cannot shoot these pellets with any degree of precision. The reason is that these pellets are heavy for caliber and why I think they were marked PCP rifle only. I will explain the phenomenom.

Heavy for caliber means that the projectile does not match the rifling groves in the barrel. In this case, the rate of twist is not significant enough to stabilize the projectile in flight and therefore accuracy suffers. For instance a .223 Remington typically shoots a 50-60 grain bullet in a barrel that is 1:9 or sometimes 1:8. The translation of those ratios are one full revolution in 9 (or 8) inches of barrel. The faster the rate of twist, the better heavier bullets will be accurate and fly true.

This is all fine until you look at the 22-250 which uses the same bullet as the .223 Remington. Those rifles come out in the 1:8 to 1:14 rates of twist with the typical being either 1:10 or 1:12. The primary difference between the two cartridges is velocity with the 22-250 being 33-50% faster. The same rate of twist equation doesn’t apply equally between these two calibers. Here is a link to an article that goes more in depth on the subject.

Generally speaking, the heavier the bullet, the faster rate of twist you want in your rifle. Like all compromises, the better you are on the heavy end of the scale, the more likely you are going to struggle on the light end of the scale. Somewhere out there, there is an optimum ammunition and barrel combination. This one is not it for me.

Now, contrast that to this target. This is 10, 10.5gr pellets at the same distance on the same rest as the picture above. I would estimate this to be about a one inch group. I fired these cold for the first time.

End Your Programming Routine: As I say all the time, know your equipment. Now that I know, I am going to burn up these heavy pellets to get to more productive practice. The truth will be that I won’t get much out of the rest of those pellets, maybe I will work on trigger and breathing discipline. I almost thought of trying to buy another PCP rifle for this fact. But then I also need a way to charge it and the rifles are pretty expensive, in a lot of cases more than a real rifle. So, maybe sometime in the future. For now, I am going to keep going to see if I can find the inflection point.