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Discussion Starter · #1 ·
I got a chrono today YAY!
And I was testing my sniper rifle with various springs. I put in one which puts out washed .25g King arms bb's at 491 fps.
I fired ten shots and everyone was between 491 and 492. Then maybe one in twenty being 490 r 493.
I though the general consensus is the higher the FPS the less consistent.
Yet at one joule the it is 290-293. w/ the same bb's.

So I decided to try out .3g golden ball (also washed) and it was between 450-454 approx.

I thought heavier bb's yield more consistent results? Could someone please elaborate?

BTW for the .25g bb's the consistency went from 1fps to 3 (Difference between washed and non washed)

Thanks.
 

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There are several factors going into this. Consistency, resistance, performance of parts and maybe more. First, you have nothing to worry about if you velocity is moving 1-2 FPS between the said speeds. I am just going to suggest some possible causes since I am not a physicist.

Consistency has a lot to do with your seals but also the repeatability of a task. If some parts begins to drag more than normal, it could affect velocity. If the spring does not react exactly the same it could effect velocity. BBs do not weight the same even though they are coming from the same bag (.205-.195). And, BB diameter plays a role in consistency too. Holding your gun 3" away from the chrono and then again at 0" can make a difference in expected results. You hopup could as well, since each setting it can be ideal for certain weight BBs. Of course you could just have you BBs in backwards.
 

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Discussion Starter · #3 ·
I've changed spring several times (as in tested with three different springs) and I cannot repeat the consistency I was getting. I mean it was 421, 422, 421, 422, 421, 422, 421 exactly. Now it's more like 422, 425, 421, 423, 420, 422, 428, 424, 422. It's just really annyining.
Then with a weaker spring it's varying more than normal too.
 

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Depending on the ranges you are shooting for, I wouldn't worry about it. Its not like you are going to see a huge impact from +/-5FPS deviations under 200' that you couldn't just as easily blame something else anyway.
 

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Discussion Starter · #6 ·
mateba said:
Depending on the ranges you are shooting for, I wouldn't worry about it. Its not like you are going to see a huge impact from +/-5FPS deviations under 200' that you couldn't just as easily blame something else anyway.
I know it doesn't really effect it but I had bragging rights at my sight with the +/- 2 fps. Then +/- .5-.8 fps.
Ah well.
 

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Something I've noticed, while a little extreme, is how far the gun is from the chrono.

Something I've looked at is the varying velocities with the gun shooting at different angles, and at different distances from the actual sensor of the chrono. While for a field event, or just to get the feel for the fps, it works just fine, but, when you start to test for consistency, you'll start running into problems. Just a few degrees off can shave off several fps, an inch forward or back can do the same thing.

The research was done to explore how people might get around chrono readings, however unlikely, we were able to produce about a -10-15fps variation depending on the chrono and the angle/distance the shot was made. Using something small works better, but still, very small variations can lead to a few fps of variation. It makes it very hard to read into consistency.

I was once under the impression that I had a gun with less than 1 fps of consistency. While that may still be the case, it would be almost impossible to properly measure without a vice grip to hold the chrono and gun in place.
 
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