bioval BBs + hopup issue

[vancouver_sc]

Whenever I use bioval BBBMAX, first 4-5 shots are fine, then it's like the hopup no longer works and the BBs don't get enough spin.

If I replace them with normal BBs, this doesn't happen and hopup works just fine.

Any ideas?

[Eeyore]

What fps is your gun shooting at and is it a hard or soft rubber?

[Scarecrow]

Originally Posted by vancouver_sc

Whenever I use bioval BBBMAX, first 4-5 shots are fine, then it's like the hopup no longer works and the BBs don't get enough spin.

The BBBMax is a silica product that is very hard - if your hopup mechanism isn't tight, it could be gradually forcing the nubbin (the little rubber doohickey that sticks up making the hopup lump in your barrel) back down and actually turning the mechanism, and shutting your hopup 'off'.

Try this and report back.

1. Adjust your hop up. Make note of the hopup control wheel's position.
2. Fire the BBBMax until you get that effect you described.
3. Check and see if the hopup control wheel has rotated.

IF the wheel has not rotated, let the gun sit for an hour or so. After an hour, without adjusting the hopup, fire some more BBBMax. Is it firing back to normal or is it still wonky?

If it fires normally, then the hopup nubbin is being crushed by the BBBMax and is bouncing back from the crushed shape, reenabling the hopup effect - you need a stronger nubbin.

If it is still wonky, I suspect the hopup mechanism is adjusting, or the nubbin is staying crushed.

Thats my theory.

[vancouver_sc]

The gun is shooting around 420 fps.
I've tried both TM soft rubber and Guarder hard rubber, the same issue.
And no, the hop-up wheel doesn't rotate itself after shooting.
I think it has something to do with the glass-like surface of the biovals, very sensitive to small impurities/dust?

[Amos]

Scarecrow's suggestion makes sense in my mind,

Try a Shredder's Concave spacer, they're a hard plastic that wont take shit from no hard BB's

[Scarecrow]

Originally Posted by vancouver_sc

The gun is shooting around 420 fps.
I've tried both TM soft rubber and Guarder hard rubber, the same issue.
And no, the hop-up wheel doesn't rotate itself after shooting.
I think it has something to do with the glass-like surface of the biovals, very sensitive to small impurities/dust?

I'm 99% you're dealing with a crushed nubbin. Did you do the shoot-after 1 hour part of the experiment? That would tell you if the nubbin is coming back into shape after.

[vancouver_sc]

I've tested different nubs, harder, softer. Same issue. I'm gonna try one which you can't compress at all - 100% filled.