After reading about teflon mods and such,
I decided to look into the nozzle to cylinder head tip seal..

It was alittle loose, and doing a compression test, I found that air could leak out
albeit at a "slight" rate.. Probably negligable since the piston compresses air at
such a "high" rate..

At first, I thought about modifying the nozzle itself but I could not find anything
thin enough to fill the very slight gap between it and the cylinder head tip.
I didnt want to use Teflon or a coating because they would eventually wear off..

So I decided today to "slightly" ream the cylinder head tip to fill the area where
the seal is vital. That being its "Tip" and the nozzles "Middle"

As shown in the diagram:
The RED points out areas where leaks are possible.
The BLUE points out the "reamed" out tip of the cylinder head tip
Which is brass & expands nicely without cracking...



This is a picture of a .22 cal shell casing. It is what gave me the idea to begin with...
As they are sort of crimped at the tip to hold the bullet,
So why not expanding the diameter instead of reducing it?


I used a cone shaped piece to work the diameter until it formed a better fit inside
the nozzle... It was just trial and error until it slid in easy, but passed the compression
test better than stock... a 100% seal would have made it too tight, and potentially
cause tappet plate breakage or feeding issues.. So I stopped when it was "better".
The reamed tip was then polished and rounded to ease its movement against the
inner surface of the nozzle.

I tested the gun on a line of cans of varying brands..
(Coke, Sprite, Canada Dry, Mountain Dew)



Top row (3) and (3) are Mountain Dew
Second (2) on the right are Canada dry
Third (1) and (2) are Coke
Last (1) on the right is Sprite

I had a few cans left from "Before Mod" tests to compare to..
The "Before Mod" tests show rips, but only slight...
Before the mod, at the most shots would knock a wedge out about 2-3mm
This pic shows the lower spectrum of "Before" results:


This "After" picture shows how a couple BBs almost went through the bottom..
The hole made by the BB ripped a wedge out of the bottom about 5mm


It appears "After Mod" the Average is 2-3mm wedges and a couple
"Almost" penetrations..

Not sure what the FPS gain is as the BBs still don't go through,
but at least there seems to be a gain however slight..

All tests were done the same...
Can unsupported
Muzzel 3 inches away
Hopup Off
Clean barrel
AE 0.2g BBs

Of the same brand cans side by side there is a difference in degree of penetration..
But not enough to form an average, as I only had a few "before" cans to compare to.

In summary, rather than coating or altering the nozzle I think its better to expand the cylinder head tip.
It should hold up to wear much better. This can be done to virtually any stock cylinder head.
Although a replacement nozzle is cheap enough to buy & test, the $10-12 can be better used
on a bag of 3000 quailty BBs!

I don't have a Chrono yet, but I was pleased that the results showed some sort of gain,
whatever FPS it may be... I know Coke-Can / Poor mans test results arent an accurate
indication of FPS, but IF they were true, the FPS would be somewhere between
340 and 385.. and Since it was able to penetrate both sides from the very start,
it may be more towards the middle/higher end of that range considering there was an
improvement since then.

Side tests show that the second side is torn open much more than before as well..
Before, it would rip a large crack in the first side, then rip 2 small flaps on the second.
Now, it rips a larger crack in the first side, and a clearly larger exit hole on the other.

This post has been edited by Noobie: Jan 7 2007, 09:40 AM