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Losing energy with heavy weight bbs

3.2K views 1 reply 2 participants last post by  1tonne  
#1 · (Edited)
I'm using an Echo-1 PSR with the following mods and upgrades

AA 430x6.03mm inner barrel
ML lever
ML 70° bucking
Fully sealed cylinder
507fps with .20 bbs

If I understand all the info correctly I should use 0.43g bbs because of my cylinder to barrel ratio, but the joule measure is not the one that I expected.

0.20g - 507fps - 2.38j
0.30g - 418fps - 2.42j
0.40g - 322fps - 1.92j

I don't have access to 0.43g bbs atm, but I've played with 0.30g, 0.32g and 0.40g, the best results so far are with 0.40g bbs, but I was expecting more joules with that bb weight. Should I buy 0.43g bbs and use those or should I stick with 0.40g? It's worth the joule drop from 0.30g to 0.40g or should I use 0.36-0.38g bbs to have more energy?

Is worth mentioning that I can overhop 0.40g bbs with my current setup.

Edit: I measured my BASR fps in the field last Sunday, with little to no time for hop up adjustment and 2-3 shots per bb weight, so the numbers might be off.
 
#2 ·
Normally if I have a rifle firing around 500fps I would use 0.36-0.4gm bb's. The rifle won't have enough energy to push the 0.43gm bb out to long ranges though they will still shoot OK but you are better off sticking with the 0.4gm that you already use.
The reason why your 0.4gm bb is losing energy is because you have leak between the air nozzle and the bucking. Since you need more hopup to use the 0.4gm bb, this creates more downforce on the bb and so it is held that little bit longer in the bucking which allows pressure to build up. Since there is more pressure, the air bursts out between the bucking and the nozzle. If you get an AA VSR10 Hopup Chamber, you should see this issue fixed.