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Old December 19th, 2007, 22:58   #1
CDN_Stalker
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BB weight vs. fps drop *rough* testing

Testtube came by tonight to discuss stuff and business (as well as drop off a bag of 0.20g and 0.25g Bastards as gifts to me.......... is good to be in partnership with the local Bastard!) and he and I did some rough chrony results with my new F1 Chrony and my CA M24 (Laylax/First Factory 150SP spring, used for 2 solid years and showing wear, Guarder 9mm bearing spring guide, Guarder piston and piston head, Prometheus 6.03mm tightbore barrel and RH65 hop up rubber) to see what differences BBs from 0.20g to 0.43g BBs had in relation to each other (about a foot away from the chrony). Since I'm running really low with the Straight 0.36g and 0.43g BBs, we only tested three shots of each, got an average and sorted out the differences in weight vs. fps drop. I figured this might prove interesting to some, and also gives rough estimate of fps if a gun is chronied with 0.20g BBs but the user wants to know about what 0.25g or 0.28g BBs might sit at in use from the muzzle.

BB Bastards:

0.20g

468.8
457.1
467.9
Average: 464.6fps

0.25g

429.9
425.3
430.2
Average 428.46fps

0.28g

397.9
403.0
400.1
Average 400.33fps

SIIS

0.30g

394.4
392.3
389.3
Average 392.00fps

Straight:

0.36g

359.7
366.9
355.8
Average 360.8fps

0.43g

336.2
340.3
335.2
Average 337.23

So, what we have for differences between weights (velocity vs. weight difference)is:

0.20g @ 464.6fps
\
}-36.14fps for +0.05g
/
0.25g @ 428.46fps
\
}-28.13fps for +0.03g
/
0.28g @ 400.33fps
\
}-8.1fps for +0.02g
/
0.30g @ 392.0fps
\
}-31.2 for +0.06g
/
0.36g @ 360.8fps
\
} -23.57fps for +0.07g
/
0.43g @ 337.23fps

Hope this provides some useful info, even if it's just basic stuff (again the word rough pops up, but seems a trend to count on for rule of thumb guessing is 10fps decrease in velocity for every 0.02g difference in BB weight increase.)

PS: Gonna post this around, so don't be surprised to see it elsewhere.

Last edited by CDN_Stalker; December 19th, 2007 at 23:04..
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