FPS different weight pellets

[Yandeltx]

Let’s assume same gun shooting same PSI how much faster would a pellet that’s 20% lighter shoot over the heavier pellet?

 

[dizzums]

thats alot of math man and its late lol .. id guess 150fps ...

 

[Mycapt65]

Weight isn't the only factor in velocity. Fit and skirt design can affect it to.

 

[Yandeltx]

I will answer my own question, I rigged up the chrony this morning.

18.13 = 843 fps. JSB
14 gr = 943 fps CPHP

Just in case inquiring minds want to know.

 

[ImpactX]

I'm shooting .25 cal impact. Going from 34gr jsb to 25gr jsb, I get 100 fps increase. I also shoot 33gr nsa slug and 36gr nsa slug and its about 50 fps difference.

 

[bigHUN]

Keep in mind that for a best POI each different weight pellet "need" different - its own psi/bar tune. Yes you can shoot the pellet whatever speed you like, but the POI grouping won't be the same.

 

[badger5th]

My data with a Beeman R9 0.177cal springer:

H&N FTT green 5.71gr. 1,140 fps. 16.5 fpe
Crosman Domed 7.0gr. 950 fps. 14.0 fpe
H&N FTT 8.64gr. 860fps 14.2 fpe
JSB monster diabolo 13.43gr. 700 fps. 14.7 fpe

 

[Trucker3573]

I will answer my own question, I rigged up the chrony this morning.

18.13 = 843 fps. JSB
14 gr = 943 fps CPHP

Just in case inquiring minds want to know.

Had the question been phrased directly with those ammo weights I could have answered that. Done those tests many times and yes the 18’s are always just about 100 fps slower.