Category: Tacticool

September 8, 2022 – ‘Tacticool’ Thursday

September 8, 2022 / bhayes952

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.

	1	2	3	4	5	6
1	219	399	497	565	618	657
2	223	400	504	562	615	659
3	226	392	498	568	617	662
4	231	400	502	561	616	666
5	226	398	493	564	622	664
6	220	402	494	568	618	664
7	220	396	500	566	611	663
8	225	389	499	563	618	669
9	232	397	502	559	623	665
10	218	398	497	567	613	668
	224 +/-15	397 +/- 12	499 +/- 11	564 +/- 10	617 +/- 11	664 +/- 11

values in fps

	7	8	9	10	11	12
1	701	726	752	775	798	812
2	700	732	755	781	796	808
3	698	727	751	779	799	803
4	688	730	760	781	793	802
5	695	729	758	771	790	810
6	695	729	758	772	797	803
7	699	725	763	774	798	811
8	696	728	758	773	798	807
9	695	724	757	777	795	809
10	693	723	757	777	789	811
	696 +/- 11	727 +/- 8	757 +/- 11	776 +/- 11	795 +/- 11	808 +/- 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.

September 1, 2022, ‘Tacticool’ Thursday

September 1, 2022 / bhayes952

So I found more stuff to test, what are you going to do about it? As I pull my son’s Crossman 760 off of the wall, I saw my Daisy 840 looking all lonely. This was my one and only air rifle until about five years ago.

This was the quintessential air rifle of a country boy. My brother and I had the same model. Many a time, a rope was tied across the barrel and the grip and then off on our bikes or trekking through the fields. Our favorite thing to do was take old catalogs and setup on the deck. We would shoot the catalog for half an hour and then leaf through to laugh at what we had hit on the inside pages. We shot things that we were not supposed to but I think that was a rite of passage and made me the rifle shooter I am today.

Time and kid’s ownership was not good to these things. My brother’s broke where the grip was attached to the action turning it into a stockless rifle. Mine, the spot welds broke on the rear sight leaving it more of a guess than an actual rifle. I was able to super glue it for a couple years but that has long since fallen apart and now lost forever. The forearm is also split where the two plastic halves are joined together. So far, it is still usable.

I first realized that it was time for an upgrade when I had a family of racoons living under our kitchen about five years ago. We were eating dinner on our deck and it was in the tree right next to us. I shot it to try and chase it away. When the BB hit it in the chest, the animal brushed the spot where it was hit and slowly climbed out of the tree and sauntered away. I realized that this was not going to work in a pest elimination capacity. That is when I bought the Crossman Legacy 1000.

The Daisy 840 was a single pump BB/pellet rifle. I did some research on this rifle to see if I could learn anything about it. Apparently, it was made between 1978-1986. It advertised 300 fps. My brother’s came with a scope which was broken within a six months, mine did not. I tested it to see how it was going to compare the the 760 and at first, I was only going to use BBs since the magazine was full. I quickly found out that this thing shot all over the place and my trap was not holding BB’s (when it hit where I was aiming).

	840 BB	840 pellet	760	1000	Optimus
1	263	180	579	775	944
2	307	248	544	781	942
3	285	239	540	779	968
4	282	265	542	781	936
5	264	257	549	771	938
6	200	248	541	772	965
7	180	223	529	774	940
8	242	223	539	773	906
9	189	263	552	777	964
10	132	230	554	777	953
	234 +/- 169	238 +/- 76	547 +/-40	776 +/-11	946 +/- 55

All values in fps

All values were measured at the muzzle and each rifle was pumped to the maximum (1 or 10 pumps) using the Crossman 7.4 grain wadcutter pellet. This was an attempt to compare the maximum performance across the spectrum. The thing that struck me was the inconsistency of the the 840.

Before I get too down on the 840, it needs to be said that this rifle is almost 40 years old and hasn’t been well treated. I am considering trying to do some minor seal maintenance by adding some lubricating oil. There has literally nothing ever done in that manner to the rifle.

Despite that, I was a little shocked when I missed the target multiple times standing five feet away. In all of this testing, this is the only occasion where this has occurred. The difference between BBs and pellets is that only pellets are stabilized (and therefore accurate). But, I was capable of hitting targets fifty feet away in one shot as a youth with a BB. My operating assumption is that the wildly varying velocity is causing the accuracy problems, so we will see.

I also had to double cock the action each time I shot a pellet. I am not sure what that problem is. I didn’t seem to have that problem with BB’s and I don’t understand what the different types of ammunition would have to do with the problem. That is a wait and see problem.

End Your Programming Routine: If my relubrication efforts fail, it may be time to end the run of the Daisy 840. There are no serviceable parts, it is missing a rear sight and I can’t trust the accuracy or performance. A single pump is pretty nice for shooting a lot, even if it is not the most powerful tool. But, if you cant keep the shots within the backstop, it is not safe.

August 25, 2022 – ‘Tacticool’ Thursday

August 25, 2022 / bhayes952

Bonus! I know that I said only one more in this line but I wanted to know something else while I started testing. My son has a Crossman 760 that I was curious how it compared to what I was doing.

The 760 is to prototypical first air rifle. It is affordable and ubiquitous. Most people I knew had one growing up. It can fire BBs or pellets and pumps from 1 to 10 pumps for variable power. Think of it as a value proposition, it is the most bang for the buck.

As all youth’s air rifles do, this particular one has a history. My wife and son bought it at an auction for the private school my kids were attending years ago. They paid probably double what it was worth but they won. My son was very excited at the time. However, it has mostly sat in the corner since the initial outing at the range. Here is the data that I found.

	760	1000
1	579	775
2	544	781
3	540	779
4	542	781
5	549	771
6	541	772
7	529	774
8	539	773
9	552	777
10	554	777
Average	546 +/- 40	776 +/-11

All data in fps

I was surprised to see that the 760 is significantly less powerful than the 1000. This was a new pellet, the Crossman 7.4 grain wadcutter, ten pumps each measuring the muzzle velocity. The data for the 1000 is part of the new data set I am doing in my number of pumps vs. velocity analysis coming next week.

The boxes are long gone. I really don’t know what the published velocity is supposed to be. According to today’s literature the velocity is 350-700 fps for the 760 and 750-1000 fps for the 1000. Those numbers are going to be subject to the weight of the pellet as you have seen from my previous data.

I actually have one more BB gun to look at which I will do in a couple weeks. I haven’t done any testing with BBs but since I was checking the catalog of performance, I was curious. I will talk all about that then.

End Your Programming Routine: I have to say, the 760 is much easier to pump than the 1000. I have a feeling that the longer forearm on the 1000 is an indicator that the air chamber is bigger, hence how to get more velocity. I am much preferring my break barrel spring air rifle to pumping 10 times to get similar velocity. But, for a kid this is a fantasy come true.

August 18, 2022 – ‘Tacticool’ Thursday

August 18, 2022 / bhayes952

We finally get to the whole reason for doing weeks of testing today. My initial question was what difference does the pellet weight make in energy. Or said differently, what pellet would be best to eliminated pests. Is a heavier or lighter pellet better? My opinion is that the highest energy pellet is the best. To calculate that, I need to know the velocity of the different weight pellets.

On the left is the Crossman Powershot 5.4 grain and on the right is the Gamo Rocket 9.6 grain. You might recall to date, all testing has been done with various models of the Gamo 7.54 grain pellet. An interesting anecdote about the Powershot is that I was reading reviews about it and apparently can penetrate 16 gauge steel in the right circumstances. I bought it because it was light, for comparison purposes.

5.4gr Muzzle	5.4gr 30′	7.54gr Muzzle	7.54gr 30′	9.6gr Muzzle	9.6gr 30′
1006	879	942	849	864	797
1028	884	946	853	855	777
1028	901	966	866	855	785
1005	904	959	859	857	798
1040	875	953	855	847	795
1007	880	952	870	848	784
1049	913	973	852	840	793
1039	885	947	853	852	787
1027	895	951	868	840	786
1036	903	966	858	844	791
1026.5 +/-46.9	891.9 +/- 38.9	964.6 +/- 19.5	857.3 +/- 22.2	850 +/- 23.4	789.3 +/- 20

All values in fps

Why do I keep measuring velocities at two different distances? I am hoping to get enough data that I can calculate (or guess) velocity at distance and have an educated guess at performance with one measurement. Using formulas I have discussed in the past, here are the results in energy at target distance.

5.4gr 30′	7.54gr 30′	9.6gr 30′
9.5	12.3	13.2

All values in ft*lbs

From the data, it would appear that my hypothesis is correct for my assumption. The 9.6 grain pellet has the most energy at target range. Therefore, this would be the most effective pellet for pest control.

I want to point out that energy should not be the sole determining factor in selection of ammunition. Barrel rate of twist can only stabilize projections within a certain weight range. That really translates to accuracy and consistency. There are additional considerations for wind drift as well. The lighter the pellet, the more likely wind is going to effect point of impact as well. That variable is more difficult to test, but it is a known fact. Finally, depending on the distance of the target and the overall velocity, pellets drop based on the rate of gravity, so the slower the pellet the more drop at distance making aiming (and accuracy) more difficult.

End Your Programming Routine: I hope that you have enjoyed my mini-series on pellet ballistics. I have learned a lot as well as re-awakening some long dormant brain cells on math. I will be back from time to time with this line of writing because I have thoroughly enjoyed the process and I have the tools to do it now. I have one more test in this line to complete but it is going to take a bit of effort to finish. For now, I am coming back with something different next week.

August 11, 2022 – ‘Tacticool’ Thursday

August 11, 2022 / bhayes952

I promise that this topic line is not going to go on forever. Right now, I am am having too much fun and still have too many questions. This week, I am comparing results from Crossman Optimus and the Crossman 1000 using the 7.54grain Hunter pellet. To date, all of my work has been with the Optimus because it is just a better tool. The 10 pump BB/pellet rifle (1000) is a pain in the butt to shoot multiple times.

That being said, I am going to do a pump/velocity test in the future. I want to know if it is really worth pumping 10 times or not because it 5 pumps is almost the same, then I will be more willing to shoot it more consistently. I already know that the point of impact changes with less pumps. This implies a velocity change, but I want to know definitively.

For the record, the Optimus is on the left and the 1000 is on the right of this picture. I wanted to compare as closely as possible so I used the same pellet and the 1000 was pumped to the maximum 10 pumps. The data is below.

Muzzle – Optimus	30′ – Optimus	Muzzle – 1000	30′ – 1000
942	849	752	726
946	853	740	708
966	866	749	719
959	859	748	700
953	855	743	699
952	870	743	703
973	852	752	729
947	853	755	700
951	868	736	724
966	858	737	729
964.6 +/- 19.5	857.3 +/- 30	745.5 +/- 20	713.7 +/- 35.6

all values in FPS

The Optimus data is the same data from a couple weeks ago. The 1000 data is all new. I suppose the thing that struck me was that there was not much velocity change over 30 feet. So, I did some comparative analysis below. I think that it all makes sense from what I expected.

	% Difference
Optimus muzzle vs 30′	10.8%
1000 muzzle vs 30′	4.4%
Optimus vs 1000 Muzzle	25.9%
Optimus vs 1000 30′	18.3%

For fun, I checked a couple other things. What happens if it is over pumped? With 12 pumps at 30′ I got 727, 651 and 771 fps. It looks like the data is all over the place and I didn’t do enough for proper statistical analysis. Maybe there is an overpressure valve? I don’t know and I am not really going to pursue more, I was curious what happened.

Finally, I changed pellets from the Hunter to the Magnum Energy @ 30′ 712, 711, 726 fps. I think those results were the same that I observed in the Optimus. So, that data seems to make sense.

End Your Programming Routine: The truth be told was that I purchased the Optimus because the 1000 was such a pain to shoot repeatedly. All that being said, the Hunter pellet out of the 1000 is potent enough to dispatch cat sized vermin at eight pumps in one shot. My biggest fear was needing a follow-up shot to finish the job and spending 30 seconds reloading. Let us see where the data leads.

August 4, 2022 – ‘Tacticool’ Thursday

August 4, 2022 / bhayes952

One thing that can potentially effect accuracy is the variability of the projectile. I am told that serious hand loaders weigh and sort bullets. For the best accuracy, you want everything the same. This is the only way you can have consistency.

To date, I have taken for granted that all the pellets were the same. On the container, it says that they weigh 7.54 grains. That is a pretty precise measurement. For me to technically validate that, I would need an analytical balance that reads three places past the decimal point such as X.XXX . I am not going to spend $5000 because it is not that important but that is what I would need. I do however have a scale, so I thought that I would give it a shot in just checking what my readings are.

The last digit is considered the degree of certainty. In my scale pictured above, I can only expect numbers ahead of the last digit to be correct. Or said another way, 100.0X can be certain.

When I switch the units from grams to grains, I only get 7.X as precision. This means that the reality is I cannot validate that the pellets are 7.54 grains. The best I can do it get relative comparisons. For fun, I did a couple tests. The first one was to measure one pellet ten consecutive times on slightly different locations on the scale.

Pellet	1	2	3	4	5	6	7	8	9	10
1	7.8	7.6	7.7	7.8	7.7	7.8	7.7	7.7	7.7	7.8
2	7.6	7.6	7.6	7.6	7.6	7.6	7.6	7.6	7.6	7.6
3	7.7	7.7	7.7	7.6	7.7	7.6	7.6	7.7	7.7	7.7

What can we learn from this? Truthfully, not a lot if we know that we can only trust 7.X grains. There is no absolute way to determine the difference between the two pellets. I would say looking at the data, it would appear that consistency improved greatly between measurements for pellet one versus pellet two.

From a relative perspective, it would appear that there is some difference between the pellets. Even though I cannot accurately weigh them, I am getting some different results when I switch pellets and that is consistent. I did a second test to weigh 10 different pellets.

Pellet	Weight (grains)
1	7.9
2	7.6
3	7.7
4	7.9
5	7.9
6	7.6
7	7.9
8	7.9
9	7.7
10	7.8

So, it appears that the spread is between 7.6 – 7.9 with a weighting toward the higher end. My conclusion for all of this is I believe that there is some difference with the pellet weight. If I take my measured spread (0.3 grains) and divide by the nominal weight (7.54 grains), I calculate 4%. In reality, that is not a lot but it is something.

End Your Programming Routine: There is some statistical analysis that can be done to determine how accurate your measurements are. Given my equipment’s limitations, I don’t think that it is really worth doing the analysis. This wouldn’t be a question if what I was measuring was heavier. Regardless, I think that this technique has potential to provide context in changes of accuracy.

July 28, 2022 – ‘Tacticool’ Thursday

July 28, 2022 / bhayes952

I changed my mind about what I am going to talk about today. I was reading the definition of statistical significance and there is even some debate to whether it is actually accurate. You don’t want to see the math and you probably don’t even care about the esoteric aspects. In theory, significance validates the data set. Since I measured all of the data, my equipment is either working (data valid) or it is not (data invalid). I choose to believe that it is valid.

In lieu of a more complicated analysis, I am going to talk about the difference between two different pellet shapes. What is going on? I shot all of my pellets in one container so the ones I switched to had a different shape, see the picture below.

The pellet on the left is what I have been working with. The name given by the manufacturer in ‘Energy’. The one on the right is called ‘Hunter’. Both are 7.56 grains in weight and constructed of lead. In the course of gathering data I noticed an accuracy difference, see below. This is known as point of aim versus point of impact between two different pellets.

Looking at the target on the upper left, those were shot with Energy pellets. The X represents the point of aim and you can see that the results ring the point of aim. Switching over to the Hunter, I see there is a significant drop in the point of impact from the point of aim. My point here is ammunition is not always swappable with identical results.

To address this, I need to re-sight in my scope. For purposes of just getting velocity measurements, that is not important today but it is worth noting this is the case.

	Muzzle Velocity (fps)	Velocity @ 30′ (fps)
1	951	906
2	965	892
3	974	908
4	968	904
5	960	906
6	965	905
7	956	909
8	971	909
9	963	907
10	970	908
	964.6 +/- 19.5	905.4 +/- 15

You will recall from previous weeks with the Energy pellet I got 955.8 +/- 30.3 fps and 857.3 +/- 22.2 fps. That is a percent difference of 0.91% and 5.45% respectively comparing Energy versus Hunter pellets at muzzle and 30′ readings. In my mind, the data says that muzzle velocity is about the same, however there is a clear velocity difference at 30′ between the Hunter and Energy pellets.

I think that it is also worth noting that my numbers are becoming more consistent. There is a pretty narrow window that the pellets need to travel to for the chronograph to read. I am estimating that my failure to read count has dropped by two thirds. So, I would say that I am getting better using the tool. Regardless, this is why we do math on the data. This is the term normalized.

End Your Programming Routine: You are now on your way to becoming an actual physicist. I didn’t publish a hypothesis before I started this but if I would have, I would have thought that the Energy pellet would have more velocity at 30′ than the Hunter based on shape alone. Since there are only two variables in calculating energy, mass and velocity and the mass is the same for both pellets, it seems like Energy is actually misnamed.

July 21, 2022 – ‘Tacticool’ Thursday

July 21, 2022 / bhayes952

We are back to math again. I am today we are going to talk about percent difference. Percent difference is comparing two measurements and quantifying the difference as a percentage. I have the measurements of the velocity at the target.

Taking what we have learned so far, I am not going to go over the calculations again, but I will present the data.

That leaves me with an average velocity of 857.3 +/- 22.2 fps at 30′. You might ask yourself why you would want to know this information? Well, first of you rarely shoot something that is at muzzle length so you want to judge the amount of energy at some distance (effectiveness). I can also calculate the estimated amount of bullet drop over distance (performance). There is also some some consideration to gravity and the effect of friction. I would call that percent difference.

End Your Programming Routine: At some point in the future, I may decide to look out farther in distance for another data point. But I shot up all of those particular pellets which makes a true (scientific) comparison not possible. So, my next look is going to be the data that I have collected versus a new shaped pellet of the same weight. With that I am going to talk about statistical significance next week.

July 14, 2022 – ‘Tacticool’ Thursday

July 14, 2022 / bhayes952

More math today, hurray! I hope that I am bringing this in an approachable fashion because I find it interesting. It’s one of the ways to sort of geek out in the area without spending a whole bunch of money. Math is essentially free after the experiment is done.

Today I want to talk about Standard Deviation (often represented by SD). You can get super in the weeds with the extra places you can take the math, but that we will not do. So what is it? Standard deviation is statistical modelling to predict the probability of values following within a calculated range. Or said another way, what can I expect my velocities to be based on the measurements that I have taken.

Let’s not get scared but there are a couple mathematical terms to discuss. The first is that this simple calculation is going to only look between the the first two divisions (called the Greek letter sigma). One sigma (or deviation) are values representing 68% of all the measurements (or the majority).

We will assume that the data is normal and distributed like the graph. In that case, we can just multiply the standard deviation we calculate by 2 to get 95%. Same with getting 3 sigma. The mathematical description of sigma is variance. The variance is the average distance between the calculated mean value. This is why we can simply multiply the variance by a factor.

One reason to do this is that you can create expected behavior. Another one is that you can validate that your equipment is working properly (using the higher level math). I will leave it at that since I feel like if you are not convinced already, me keeping on probably won’t help. Using my data from last Thursday, let’s get into the calculation.

To really get to what I am saying here is that 68% of the time, the velocity is going to fall between 945.7 and 965.9 feet per second. That translates to the mean minus the standard deviation (955.8 – 10.1 = 945.7) and the mean plus the standard deviation (955.8 + 10.1 = 965.9). And finally, 99.7% of the pellets will be 925.5 – 986.1 fps.

Of course, like the supreme court this is a very myopic look at things. This is a 7.56 grain pellet, velocity measured at the muzzle with no wind, 65 degree ambient temperature and 50% relative humidity. I am going to look at some of the other variables as time moves on.

End Your Programming Routine: Hopefully, that made some sense. You can also use excel to do this without understanding the formula if you can figure out how to make formulas work. My points today are 1) this is possible to do relatively simply 2) my rifle is pretty consistent 3) and now I have some data to compare other experiments against. Next week, I am going to look at velocity at the target.

July 7, 2022 – ‘Tacticool’ Thursday

July 7, 2022 / bhayes952

During the holiday weekend, I finally got some time to mess around with my chronograph. My initial test was not very favorable. I wasn’t able to get any readings the first time I messed with it (before vacation). But, I spent some time last Saturday to try and figure out what was wrong.

Today, I am going to talk about math again. I know, I know it is less fun than watching paint dry. I want to talk about looking at the dataset, calculating average with standard deviation and energy as a result of my velocity measurements. Should be fun.

A quick aside about math. We use math to describe physical behavior. I am not just solving problems for problem sake, like sudoku. I am looking at the data so that I can compare certain behaviors like 1) how consistent is the rifle 2) is a lighter faster pellet better than a heavier and slower pellet (when I look at the energy)? 3) Does pellet shape make a difference with the same weight?

Maybe it is the cold medicine talking but I came up with this idea this morning. Art and math are very similar. Both are attempting to describe life in different ways. One is by representation and the other is by description. One is subjective by interpretation and the other is deterministic, using concrete laws and methods. What I am trying to say is that you don’t have to know how to do math (like art) to appreciate what it does for us. Unlike art, I can show you how I got to my final numbers.

I went about this in a pseudo scientific way. I shot a bunch of times and recorded the data that I liked the best. In all seriousness, I need to spend more time with this device to understand what a good reading looks like. However, I had a lot of readings that were similar and some that were way off the reservation. I threw out those measurements as outliers. In science, those would have qualified reasons to be excluded. There are mathematical ways of proving those outliers, but that is super advanced math. That being said, I am just going to ignore them as bad measurements.

Here is the dataset I ended up with (feet per second or fps). I think you can see why excluded the results in the images above.

The first thing that we need to calculate is the mean. Another word for that is average.

What I have calculated is the average pellet velocity is 955.8 fps. We will need that number to calculate the standard deviation. It looks reasonable so far but I think that I will save that calculation for next week. Before I end, I will plug the average velocity into the energy calculation because that is the number I am looking for to compare everything in the future.

End Your Programming Routine: If I assume that the outlier measurements were problems measuring and not exactly irregularities firing the rifle, I am pretty impressed with the consistency of the velocities. I did ignore values that did not change after firing. Again, I don’t know if the velocities were the same, but I assume that the pellet did not measure. Give me some time with this device and I can have more confidence in the actual results.

Archives by Month

Recent Posts

Recent Comments

Categories

Meta