Pneumatic gun performance – misunderstanding

[tromic]

When we are talking about gun performance it is necessary to specify at least:
Barrel diameter (11mm/13mm),
Shaft diameter (6.5mm, 7mm, 8mm),
Pressure in the gun. (30bars/20bars)

-Some 11 mm barrel guns with 7mm shaft should not exceed 30 bars (manufacturer documentation)
-Some 13 mm barrel guns with 8mm shaft should not exceed 20 bars (Asso), 30 bars (Mares)

I noticed that users use their Asso guns, with mamba, at 24-25 bars (this is 13 mm barrel, 8mm shaft)
If you use Cyrano (11mm barrel, 7mm shaft) at 24- 25 bars there is unsatisfactory performance.
This two guns could not be compared this way. To have similar performance Cyrano should be at 33-34 bars.
If you use Cyrano with 6,5 mm shaft, 27 bars could be enough for good performance.
I think you get what I want to say.

 

[cousy]

Tromic,


You are correct about the max pressure for the ASSO being 20 atm. I don't understand why their maximum charge is so low. However I own a number of the old Competition Series Mares guns with 13mm barrels and all but 2 of them have a maximum charge pressure of 30 atm. The other 2 have a max rating of 35 atm.

 

[tromic]

Tromic,


You are correct about the max pressure for the ASSO being 20 atm. I don't understand why their maximum charge is so low. However I own a number of the old Competition Series Mares guns with 13mm barrels and all but 2 of them have a maximum charge pressure of 30 atm. The other 2 have a max rating of 35 atm.

Cousy, you are right. I checked for Mares Sten: 30 bars, not 20. I made a correction. But that is not so important. I just want to say that one can not compare guns by applied pressure if they have different barrel diameter. It could cause misunderstanding. If asso with mamba would be very good at 24 bars (actualy overpressured) than it does not mean that Cyrano with mamba would be good at the same pressure.

 

[cousy]

I agree that you can not compare the performance between a 13mm and 11mm at the same pressure. When Mares introduced the 11mm barrel they claimed that it boosted the performance by 20%. This is no longer true when the gun is converted to a dry barrel since there is no water in the barrel to expel.

This does not mean that a 11mm gun can not be just as powerful as a 13mm dry barrel. If you increase the pressure in an 11mm barrel gun until the loading effort is equal to a 13mm barrel gun they should both shoot the same. I believe the Mamba guns can be pumped up to 30 atm and at that pressure they should have similar performance to a 13mm gun charged to 23 atm.

I would like to thank you for your post on your dry barrel conversions because it inspired me to design one of my own. It is a different design from yours but I did use your I idea to cover the exhaust ports with a rubber tubing.

 

[tromic]

I would to say thank you for your post on your dry barrel conversions because it inspired me to design one of my own. It is a different design from yours but I did use your I idea to cover the exhaust ports with a rubber tubing.

cousy, I would like to see your solution too.

 

[cousy]

I will post it in a new thread after I take a few photos of the conversion. It is very simple and cheap to make. The most expensive component for the conversion was the rubber tubing that I used to cover the exhaust ports.

 

[foxfish]

We will look forward to the new thread, can you post a link on this one please.

 

[cousy]

Okay, here is the link. http://forums.deeperblue.com/pnumat...other-dry-barrel-modification.html#post775964