Canadian Airgun Forum

I got the bulk CO2 conversion completed on my QB78 deluxe as well as a chrony from a fellow forum member. So I did some test today outside in my backyard.

Test Setup:

QB78 Deluxe, attached with (in sequence) bulk fill adapter, 1/8 Quick Disconnect, Remote Line, On/off valve, 9 oz CO2 bottle (At about 8 oz full)

10 seconds shooting sequence:

Pull bolt Back
Record Velocity by hand
Grab Pellet
Load Pellet
Aim
Shoot

I completed all of the above actions in about 10 seconds and I did that for 65 shots straight. I stopped at 65 shots because I run out of pellets on hand and I don't want to ruin the data with one minute break running back into house for pellets. Here are the results. I am very impressed, pleased, satisfied, and amazed.

It may be appeared as that muzzle velocity is decreasing near 47-50th shot, but bear in mind that the drop is less than 10 fps. If I set the minimum velocity at 0 fps for the graph, all we gonna see is a straight horizontal line (well, pretty much). Please also consider the fact that the CO2 bottle possibly could not absorb the heat fast enough to reach steady state in 10 seconds.

Here is the full data sheet in google doc

Please tell me which bulk fill setup you are using? Are you leaving the hose connected and the valve open? I have something similar but I am not getting the same results as you.

_________________
Tim
CSSA, ORA
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Blow ye winds like the trumpets blow. But without that sound!

yes I am leaving the hose connected and valve open.

if i leave the valve closed, I will get no consistency, it will be just like 530, 520, 505, 485, 465.. like that, straight downhill decreasing fps

Here is the remote line, I got it locally in store.

Here is the bulk fill adapter, or just PM sniper in the forum, he has more expensive ones from the states.

These 2 items are the only ones I will need, the male 1/8 quick disconnect from the remote line can be screwed onto the bulk fill adapter. and of course, a 9 oz CO2 bottle. I have mine installed with an on/off valve.

Thanks man! That's exactly what I was experiencing. 520 507 498 470 etc. I was filling, then detaching the hose.

But I thought that a bulk fill was supposed to give you like 30-40 "good shots"

Soon I will be picking up a used Discovery in 177 so I am really looking forward to that. But I wish you could fill a Bulk QB, detach and get 20-30 shots all within 20 fps of each other.

_________________
Tim
CSSA, ORA
------
Blow ye winds like the trumpets blow. But without that sound!

In order to do that, you need to not use the remote line, but rather get a adapter to connect to the bulk fill adapter straight from the CO2 bottle, then you need to sort of tilt the thing and make sure some liquid CO2 gets in the QB's CO2 reservoir

In order to bulk-fill the main tube properly, you need to invert the source bottle so that you are transferring liquid CO2 to the gun.... In addition, if you shoot too quickly you will cool the gun off and the velocity will continue to drop.... Shooting about every 30 seconds is the fastest you should go.... and even then, the first few shots will show decreasing velocity until the gun reaches equilibrium....

Have you secured the valve properly against the pressure of the CO2?.... That is necessary for safety in a bulk-fill setup....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

Thanks for the help Bob,

I thought the QB78 was okay for bulk CO2 applications without modification to the valve mounting hardware.

_________________
Tim
CSSA, ORA
------
Blow ye winds like the trumpets blow. But without that sound!

Don't pay any attention to me.... I just had a brain fart and relapsed to thinking about 22XXs....

The QBs are fine for bulk fill CO2 use....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

Good news Bob. I'll try inverting the bottle.

Don't worry about the brain fart, they started with me when I turned 30.

Bottom line is when you post, I read.

_________________
Tim
CSSA, ORA
------
Blow ye winds like the trumpets blow. But without that sound!