FAC reg leak ?

[Squinty]

Haven't been out rabbiting for a couple of weeks, last time out I had a zeroing session , changed bottles and 20 shots at rabbits. The Rapid was put away without topping up the bottle.
Went out last night, checked the bottle +/- 145 bar, topped up to 210.

Had 40 shots- a  little play with the Pard 008S LRF ballistic calculator waiting for it to get dark and 8 rabbits.
Checked the pressure this morning ..down to 145 bar,  should be good for 75-80 shots.

So looking back this is definietly the second , possibly the third time that the bottle has dropped to reg pressure.
As a matter of course I checked for leaks last time because of the low pressure and fitted a new bottle o-ring.
Didn't appear to be leaking from the breather when I serviced the reg in April...although when I take the stock off later that may prove otherwise.

Clues? Seems to be on the HP side as its dropped to reg pressure both times yet held there.

[angrybear]

Well 40 shots with my fast flow FAC (.25 @ 45fpe) from a 210bar fill would be down to below 140bar, so depending on the bottle heat when filled, I'd say you're not far off what I'd expect.

[jackrooz]

either the 2 little seals in the reg core ..or possibly valve face ,or stem seal


balloon over the barrel / mod



do you leave with the hammer locked down or unlocked and left loose

[Squinty]

either the 2 little seals in the reg core ..or possibly valve face ,or stem seal
balloon over the barrel / mod
do you leave with the hammer locked down or unlocked and left loose

thats what I was thinking...but the vent isn't leaking .
Its not creeping either although if I strip it down to replace the o- rings (again) I could always put the core in the lathe and reface it.

The valve is not leaking via the barrel. Checked and double checked with a balloon.
Gun is left de-cocked, doesn't leak.

Well 40 shots with my fast flow FAC (.25 @ 45fpe) from a 210bar fill would be down to below 140bar, so depending on the bottle heat when filled, I'd say you're not far off what I'd expect.

Hmm..this is a short chamber R7, .22 (30ft- 975fps with Express) and it was giving me 75+ shots with 10fps spread and best part of another mag for 25fps drop
My third go a running this on a reg and there is always something not quite right.
I could revert to fast-flow again and still get 50+at 30ft.
It would be a damned sight less hassle than this regulated lark has been.

[angrybear]

I know a few years back my MFR had a leak I couldn't find, I ended up with the action & bottle lying in the bath under water.
The leak was tiny, it took about 2 mins to form a single small bubble from the reg vent hole, but wipe it away & 2 mins later there was another.

[Ca_Varminter]

With a small Pesky air leak...
The Water bath is the Best way of finding the leak...
The complete stripping of your rapid is also preferred..
This means barrel, bolt, stock, trigger assembly and Hammer assembly!!!!
But of course, the bottle, adapter/reg and valve assembly stay in the receiver..to take the plunge
Then after the big Dunk, give it Good drying....
Blow it out, wipe everything down....

Good Luck
Stuart

[KevG]

leak detector is the best thing to use for the micro leaks ,I never use balloon on barrel idea,a smear of light oil is the best way over the muzzle  the slowest leak will form a bubble in a few seconds.
KevG

[Squinty]

I've had enough today ..thats the reg done, nose skimmed, rebuilt with just the pressure to set. Done the valve and cover, fast flow standing by if all else fails.

I'll nip down to the plumbing merchant tomorrow for some leak detector to check the back of the valve....I usually spit on my finger and wait for a bubble on the crown if the gun sounds like the valve o-rings sound a bit off..

Anyhoo..was going alright earlier, another play with the balistic calculator just low shot count again, 50 shots and it was at 145ish bar again. Not good for 480cc.

At least something is working as it should...those Express don't like to stop.

[Mickyd]

Hi which express  pellets are you using, Thanks md

[Squinty]

Hi which express  pellets are you using, Thanks md

JSB .22 14.35 grain says 14.5 on the tin
Perfect for night shooting rabbits no thwap on impact just a gentle 'tap', even managed four within yards of the next ...haven't done that in ages
Ones I had last night were all straight through headshots, accurate out to 75yds.
Not for bodyshots, they way they pass through half would have run.

[Squinty]

Yesterday I had a go at setting  the reg, the all attempts to get 145 bar ran full bottle pressure.

Reassembled it as was before the rebuild , 6 x 0.45 Belvilles (()) ((  and 0.5mm float
Tbe only change was the core length, which I had re-faced by 0.5mm;  mostly brass as the delrin had pushed back into its recess.
There was plenty of travel /adjustment remaining to cover this.

Tried new Belvilles 6x (()) ((
0.3mm and 0.4mm end float with the same result.
Also tried 5x 0.6mm () ()(  0.6mm float removed from one of Kev's short-cores that is now on my 177.
Full bottle pressure. .

Here's the confusing part, not closing  would suggest that the Belvilles are maxed out and flattened or the core nose isn't sealing?
In an attempt to rule out failure to seal I fitted the standard sub-12 stack () () () @ 0.6mm float to test longer travel.
hey presto 90 bar..which held all night.

So my thinking the reason why I was getting a poor shot count. ; the reg core has failed and the gun was running full pressure.. fast flow but strangled through the core?

when I re-faced the core nose it wasn't running perfectly true in the chuck... thinking now that although the face has trued to the lathe centre its bent at the small o-ring groove?

This reg came off my mk1. 20 that wouldn't run properly and I retrofitted fast flow... perhaps it was knackered to start with?