Lacking wind post rebuild

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davhill
Posts: 11
Joined: Wed Jul 03, 2019 12:14 am

Lacking wind post rebuild

Fri Aug 30, 2019 6:00 pm

Hi, here I am , seeking brains to be picked...again.

I've done a rebuild on my Gen 2 S410 Carbine and here's the griff.

I was seeking to solve inconsistency in pellet strikes and found this...

The hammer was not running smoothly and polishing the rail and washing the hammer in thinners has fixed this. I think somebody had lubed the
parts and this had turned to sticky varnish.

The seals have already been replaced and held pressure.

The firing valve housing was blackened and grubby and the sealing tip made Tutankhamun look healthy.
Again cleaned with thinners and polished. I put the housing back in three turns as counted and aligned nick marks I'd made.

So here's the parts list..

New seals
New hammer spring
New firing valve (black tip)
Some new socket cap screws

And the outcome?

The gun filled to 175 bar, which it is holding so far.

Now, firing shows the power in underwhelming in the extreme. At 20 yards, strikes that could puncture
the thin ply backstop merely bounce off.
Previously, I couldn't execute a fill because the valve tip was so flaky , Now, the valve holds pressure perfectly
but my S410 couldn't execute a snail.

Yours in distress, David

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davhill
Posts: 11
Joined: Wed Jul 03, 2019 12:14 am

Re: Lacking wind post rebuild

Fri Aug 30, 2019 8:38 pm

OK, here's a gloating post!

There's often a clue when things go wrong and there it was, for all to see.

Both mags had become a very tight fit and the reason for this became obvious.

The mags were fouling on the brass sleeve at the very rear end of the barrel, So, the barrel
was too far into its location. This meant that the transfer ports on the cylinder and in the barrel were misaligned, thus strangling
the airflow.

Having discovered this, my partner in crime and I used an allen key to align the two
and reassembled everything.

And lo! First go, the pellet put a respecatble pimple on the inside of plastic bucket at 5 yards.
Thereafter, at 14 yards, the gun was punching holes in our thin plywood and the grouping was back.

After a little preen, we'll try rezeroing at 25 yards so it's a matter of looking forward to tomorrow.

Cheers, David

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gdavison
Posts: 362
Joined: Tue Feb 17, 2015 6:43 am
Location: Baughurst

Re: Lacking wind post rebuild

Sat Aug 31, 2019 8:47 am

Congrats on the rebuild. Personally I would get it Chrono'd ASAP as basing a rifles power based on sound and plywood damage after a major rebuild does not bode well for being sub 12 footlb. Add you location into you profile and if you dont have access to a chrono ask and I am sure a forum member local to you may offer help
AA FTP900, AA HFT500, AA S510, FWB-800FT

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davhill
Posts: 11
Joined: Wed Jul 03, 2019 12:14 am

Re: Lacking wind post rebuild

Sat Aug 31, 2019 5:15 pm

Thanks, I'll get it chronified as soon as I can. I've put my location in my profile as suggested.

In the meantime, being able to wound plastic buckets and thin ply is showing that my AA is back up to power.
Not an accurate benchmark I know but needs must when the devil drives.

I'd like to be able to report all is hunky dory now but a couple of hours' testing in the hallway range (14yds) has
shown some encouraging results.

The 'randomosity' I described when first posting in July is still there but it's improving. However, it's showing greater consistency, probably
because the hammer and rail are pristine now and the hammer and new valve are freshly sprung.

But the problem remains.

Guess what, it's down to the pellets. So we tried a few different kinds...

I'd first used Milbros, which the barrel hates.
I tried some AA Diablo Field (.22, 16 grain), which it preferred.
Ditto H&N Field.
I then got some Powershot PRECISION ( Probably the most consistent pellet you can buy).
Oh yeah? Pull the other one, it hates them.

Comparisons, using these and my mate's GRT rifle showed that the Powershots were rubbish.
Trying my AA with the Diablo and H&N loads showed it's improving.
So, I've ordered 500 H&Ns and will probably use the Powershot (and Milbros to
cast myself a lovely paperweight.

Zofort, so good, as they didn't say in the Wermacht.

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Blackbaronfish
Posts: 3626
Joined: Sun Feb 15, 2015 6:20 pm
Location: Nuneaton

Re: Lacking wind post rebuild

Sat Aug 31, 2019 9:51 pm

So where are you located

BBF
Did I mention that I'm the only one to have attended EVERY annual meet since we started

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davhill
Posts: 11
Joined: Wed Jul 03, 2019 12:14 am

Re: Lacking wind post rebuild

Sat Aug 31, 2019 11:16 pm

Burneside, near Kendal in Cumbria.

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davhill
Posts: 11
Joined: Wed Jul 03, 2019 12:14 am

Re: Lacking wind post rebuild

Thu Sep 05, 2019 12:43 am

Curiouser and curiouser, as Alice said, this is getting wierd.
Having had everthing fitted and aligned, my S410 was up and running.
Charged to 170 bar, which is what remains in my dive bottle, it
stood in the corner happily - not!

After an unspecified time, I'd hear Pssshhht. The air was leaking
out of the two holes on the sides of the (T-bar) filler valve.
Removing the valve revealed nothing obvious. But the small O-ring
near the tip of the 'bullet' inside the housing felt deecidedly hard so I changed it.
This time, the prssure cylinder hed its charge for 14 hours and then went Pssshht, again.

The gun hadn't been touched in those 14 hours and remained untouched until it let go.
A very careful examination of the 'bullet' and valve showed clearly that the tip
O-ring seems not to do anything at all.The bullet fits into the valve metal-to-metal in its
location?

I can't think why the charge of air should appear retained but be let go at an unspecified
time for no apparent reason. The gun was in the living room at normal room temperature
and there was no other interference.

I've returned home now and left the gun with my pal. He plans to have a chat with the staffers at
a loal gun dealership.

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Blackbaronfish
Posts: 3626
Joined: Sun Feb 15, 2015 6:20 pm
Location: Nuneaton

Re: Lacking wind post rebuild

Thu Sep 05, 2019 1:03 pm

You have a small air leakage somewhere. The rifle is venting at the point there is no more pressure left in the cylinder keeping the valve closed.
They usually vent at 50 bar or there about. The usual culprit is the seal on the dog leg. The Allen bolt sometimes comes loose so it’s worth trying to nip that up first

BBF
Did I mention that I'm the only one to have attended EVERY annual meet since we started

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davhill
Posts: 11
Joined: Wed Jul 03, 2019 12:14 am

Re: Lacking wind post rebuild

Fri Sep 06, 2019 12:10 am

Thank you, Blackbaronfish, that makes perfect sense. In fact, the dogleg bolt had to be persuaded out
bcause its hex socket rounded and because John Knibbs charged a king's ransom for the wrong
screw, we had to refit the original, with the screw slot we'd cut. So, I've copied your post to my pal and
asked him to put a wipe of diluted washing up liquid on that area and do a 175 bar recharge. I'll await the outcome with interest.

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rob2hook
Posts: 39
Joined: Sat Jul 21, 2018 10:29 am

Re: Lacking wind post rebuild

Mon Sep 09, 2019 5:44 pm

Surely if it were leaking and losing pressure until it vents, then the final audible vent would be through the breech not the filler valve? It sounds to me as though the filling valve is not functioning correctly, despite the attention you have lavished on it (no gratitude). You certainly should not have metal to metal contact in there - the o-ring on the tip should be making the seal. At worst a whole new valve can be found for around £20.

Rob.

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