Bioval BBs - FPS drop?
 

In my last outdoor game I tried 0.25 Bioval BBs that were given to me as a door prize on some show.

I have noticed that FPS would drop from 390 which was nominal to the point where BBs would fly for no more than 30 feet.

Thinking there is a problem with my gun I brought my backup gun and had the same issue.

The first gun has PDI 6.01 455mm barrel with PDI W-hold rubber. The second has Prometheus 320mm (300mm) barrel with PDI W-hold rubber.

When I got home I measured with digital caliper the diameter of bioval BBs and it was anywhere from 5.88 to 5.92mm. The BBs I usually use - Madbul 0.2 has diameter 5.92-5.93 mm in average. I wonder if this could be the source of the problem.

Did anyone else had similar issue, or I am looking in a wrong direction?

I had biovals jam in pretty much every gun i tried them in, one time leading to a hop up unit actually breaking. Stay very far away

yeah the sizing sucks on them, idealy youd want 5.95-5.98mm but i had a buddy read some bbs as wide as 6.04mm biovals included. Definately gunna jam, and or lose a bunch of velocity in a 6.01-6.04mm barrel, a stock 6.06-6.08 inner they will work, or should at least but otherwise theyre useless, not to mention alot of em were not perfectly round and had alot of odd air bubbles ie: they didnt have one symetrical one in the middle but looked rather like swiss cheese when cut open

Same experience - Biovals jam.

Oh wow! Thank you guys, good to know!

I had great results with Bioval BB's... once they were put in the trash.

Same issue here. I found they work in my KWA pistol though

Save them for your tornado

Knowing biovals somehow it'll still get jammed.

Biovals are bad. My PTW chewed them up.