GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: gandalfretlaw on August 22, 2012, 03:57:20 AM
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Ok, this time I did a more elaborate shooting test. I shot 20 targets five shots each. Bags of ammo were randomly numbered so I didn't know what I was shooting. I then plugged the data into excel. I toyed with eliminating flyers but I'm not really sure that was helpful. So I charted it with flyers included and with them eliminated.
I kinda know what I made of the data. I'm wondering what others will see.
This was shot with a steel trigger Gamo Whisper 177 with a 3-9x40 scope on 5.5X at ten yards. I used a pillow on a 55gallon steel drum. I was going to use a vice but it would have taken forever to shot a hundred rounds, the pillow was a lot faster and nearly as good.
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No comments at all? :'(
Was the chart readable? I put it in an image as the rows don't line up when posted as text.
What it tells me is my best pellets are 4.47 and 4.48 (possibly even 4.49) but when I start getting into the higher numbers like 4.52 my group sizes increase. The Elevation was interesting but I'm unable to see a correlation to pellet head. For elevation I took the middle of the group and compared it to the center of the target. It did seem to be lower for smaller head sizes and higher for larger head sizes, but there wasn't a smoking gun really. I was expecting there to be a direct corelation, but I don't see one and I thought it would be going the oposite way from what it is. If anything it looks like larger pellet heads tend to hit a little higher meaning probable higher FPS.
I kinda think that 0.219 using 5.42 was an anomaly. Perhaps I simply need more data to get better averages. But I do see the 4.47 and 4.48 seem to do consistently better.
The RWS Superdomes I got from Pyramid come up 4.47 and 4.48 in random measuring and I shot fricking great with them. We'll see if I can repeat the performance for this weeks ten yard matches.
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Hi Walter,
I think most people tend to test many different pellet types first, to find one or a couple that shoot the most accurately. Domed pellets usually are the most accurate at long ranges, so I test those first in my guns. Generally, if you find that "one" (or a few types) of pellet that shoot well consistently, especially at range, the head size variances don't really affect that much, unless you are really looking for cutting-edge accuracy.
Your chart was fine, and I did notice slightly better groups with smaller head sizes too. It could show a general preference for smaller sizes. But I say, shoot lots of different pellet brands, and then perhaps work on which head size is "best" for that gun.
You can buy a pellet sampler with different shapes and weights of pellets from the straightshooters website. I've meant to get one myself, as it has a wide variety of them.
Either way, keep testing, more info is definitely good! ;D
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I'm actually thinking the opposite way though. My idea is find ideal head size first and then find pellets with those head sizes. With my theory having a sorted batch of CPHPs and using them on a given gun I can quickly determine what sizes it likes. The greatest and worst feature of the CPHPs are their variability. That I was able to sort sizes from 4.47 to 4.56 (ten different sizes) from a tin or two of pellets is amazing. It's no wonder their not the most consistent.
Also I have a high yield of sizes from 4.49 to 5.52 that should shoot very consistent in guns that like them.
After doing two rounds of such testing I'm thinking that the smallest pellet that will seal properly will produce the best accuracy.
Now armed with this information I don't see any reason to try a batch of 5.52 pellets (although I probably will anyway). Also it makes me want to get a tin of those JSB Exact Measured in the 5.50 size. I think they're called Cometa Stoenger or something like that. But I can only find them for sale in Europe.
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I may have to order some of those samplers. There's a guy on ebay doing the same thing:
http://www.ebay.com/sch/i.html?_nkw=pellet+sampler+assortment&_sacat=0&_odkw=pellet+sampler&_osacat=0 (http://www.ebay.com/sch/i.html?_nkw=pellet+sampler+assortment&_sacat=0&_odkw=pellet+sampler&_osacat=0)
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That's some pretty extensive testing there, Walter ;)
Nice work!
I never went through that much trouble when I was seeking the best pellets for my guns. I got lucky with most of them except one. I took the lazy route and bought a Beeman pellsizer, it basically resizes the pellets to an exact head size. The dies came in various sizes, so I bought the closest 3 to narrow it down to the right one.
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Wow, extensive testing. Thanks Walter.
Interesting that you found the looser sizes more positive.
Good stuff.
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So, sorting pellets is worth it?
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In my opinion, sorting pellets as a normal function is not worth it. Your better off paying $2-3 more for your pellets and getting ones that you don't have to sort. CPHPs are all over the place from 4.46 to 4.56. That's quite a drift. I do understand that the boxed Crosman Premiere pellets are much more consistent, but I haven't bought any as of yet.
I used the broad spectrum of their sizing to find out what sizes my gun likes. Then I found some pellets in that size range and surprise, surprise, it likes them very well. RWS pellets instead of being +/- 0.10 are more like +/- 0.01. I think most of the other makers are also like this. Some of them even tell you that their pellets are 4.52 for example. I just opened up a tin of Beeman pellets and although their not as consistent (+/- 0.02) they are mostly coming up around 4.49. I'm going to try shooting them and see how they do. The RWS my gun likes are around 4.48.
This all started when I noticed that some pellets were tight and some were loose when I put them in the breech of my new break barreled pellet rifle. It didn't take long for me to correspond the difference in the loading to the difference on the target. A lot of the "flyers" seem to be generated by pellets that fit differently.
Sorting CPHPs you can get pellets that shot well out of your gun, but if you sort 500 and only get 200 that shoot well you really might as well have bought better pellets.