Aa S410 Project, A Bedtime Story.

[Mister Gain 1,764]

Now there's a chance this write-up might send you to sleep as it's just a bit of a yarn really, but the 2 mates I go shooting
with have differing views, the 'old chestnut'... 177 or 22 for hunting?

I currently use a HW100KS in 22, an excellent rifle, but I recently shot a small bunny at my zero of 27 yards, and the pellet
went right through its head, and plenty of gore hanging out. We all know what that looks like so I won't post a photo.
Anyway, I thought I'd better chrono the rifle. For most of its 2 year life it has been steady at 11.7 ft/lbs, and I thought it may
have crept up. Actually it has lost 1.1 ft/lbs, (10.6 ft/lbs) so it looks like it will need a service or at least change the barrel
seal.

Well my mate who advocates the virtues of 177 said he had an old Air Arms S410 Classic in 177 he was looking to get rid
of. It had been stuck in his garage for about 5 years since he had tinkered with it. He couldn't get it above 9.6 ft/lbs, plus
there were some bits missing etc etc.. it would be something to practise on before I delve into the HW100.
I told him I would have it off him. Next time we met up at the permission he produced the aforementioned rifle, but in kit
form.

The following day when I had a fiddle with it, straight away I could see the magazine indexer wasn't there, and there was no
female fill coupling either, so I couldn't even fill it. Ended up with a bit of a list and got to work spending the pounds.
After a couple of days I had quite a few of the bits, including a new set of 'O' rings, so got to work. First of all I filled a
magazine with AA Fields 4.51's and cleaned everything up. Polished the pellet probe/bolt, cleaned and polished the hammer
guide and inside of the hammer itself, it was as smooth as glass and slid up and down really well. I did notice an extra metal
washer behind the main spring guide, but I left it there initially in case it had been put there for a reason (later removed it).
Put in the transfer port seal which my mate supplied and re-assembled everything. It wasn't indexing properly even though I
knew the new indexer was correctly fitted, so took apart both magazines to find the small springs and ball bearings were
seized, so the balls were not being pushed into the magazine notches during magazine rotation. A strip down, clean up and
spray with teflon had it working perfectly.

Filled it up with air, noticed the male filler had a slight leak, and got out the chrono.
First reading was 12.6... WTF. Straight out with the security screw (pre anti-tamper) and got an Allen key on the grub screw
and rotated it clockwise to bring the power down, took a few rotations, but got it down enough.
Reckon the grubscrew had been fully opened when my mate was tinkering with it years ago. Anyway, by the time I had put
10 pellets through it, it had dropped to 9.6 ft/lbs.. the same reading my mate couldn't get it up from. I tried and neither could
I, despite lots of trying.
I thought about it and concluded that the barrel seal O ring was probably getting brittle or worn and needed replacement, and
over the years standing idle had reformed to its original shape enough to put the first few readings over power, before
resuming its worn shape, and letting air out past the pellet probe.

OK then, removal of the barrel was required to renew the seal. I removed the scope and mounts, and then undid the 2
retaining grub screws, so that the barrel could slip out.
Wrong... it was solid, so another strip down to remove the bolt housing, in an attempt to get some purchase on the barrel
and twist it out.
Try as I might, the barrel refused to budge, I tried until my balls were in my neck. I managed to rotate it a fraction, as I
noticed the transfer port holes no longer lined up. Feeling rather dejected I spent an hour on the internet trying to get some
help. Dead ends were all I could find until I came across a sentence written by DavyT in 2011 where he said the early S410's
were held in with a superglue type adhesive and would need heating for barrel removal. What a relief. Out came the old
womans hair drier (didn't want to use a hot air gun in case the heat was too fierce and caused the metal to warp.) It worked
like a dream, and out came the barrel, only problem was that the barrel seal holder left behind the end part, which in itself
would have been OK if the transfer port was not now misaligned. It is quite a thin piece of turned brass, so wasn't going to
take much punishment.
I found that a screwdriver bit holder was exactly the right size to use as a drift, and it worked perfectly thank f**k.
I can only assume that when they were manufactured they were 'glued' in prior to drilling the transfer port holes. As such you

have to be very careful with alignment when reassembling. So the new seal was in, the holes aligned and barrel refitted.
I noticed that the transfer port seal my mate supplied was about twice the thickness of the Air Arms one, so that got
replaced by the proper one.

A refill with air and back on the chrono. Bit of fiddling and now holding pretty steady at 11.4 average. Back on with the
scope, and re-zero to secondary zero (13.8 yards-small garden unfortunately) after playing with chairgun pro, and deciding
on 35 yard primary zero. That gives a 1" killzone from 8.6 yds to 39.8 yds.
Obviously I'll zero it properly when I next visit the permission.
The blueing isn't the best but acceptable, no doubt a project for a later date.

My new sling, which needed remodelling to suit the Talon swivels (bit of cutting and sewing LOL) had arrived, along with a
BSA tactical casemat (sling), another tin of AA Fields in 4.52 and a new cylinder filler valve, which is fitted and doesn't leak,
and it's good to go.

Oi... wake up, I've finished.

[Jacko338 0]

Hi there mate, the male filler leak is usually caused by people emptying the redo out with a 5p in the screw cover to depress the ball valve, they are pretty cheap to replace if you haven't already. Bond gun accessories is worth a look for AA spares and Julian bond is good with advice and won't sell you anything if you can do without it. Hope that's of some use to you. Happy tinkering.

[Mister Gain 1,764]

Hi there mate, the male filler leak is usually caused by people emptying the redo out with a 5p in the screw cover to depress the ball valve, they are pretty cheap to replace if you haven't already. Bond gun accessories is worth a look for AA spares and Julian bond is good with advice and won't sell you anything if you can do without it. Hope that's of some use to you. Happy tinkering.

 

It's all done thanks mate, I shopped around for the parts, John Knibbs, Best-Fittings, etc all hassle free.

Just got to get out and use it.

[mattybugeye 884]

Nice job mate

[Mister Gain 1,764]

Nice job mate

 

Thanks Matt, despite the bit of frustration, I quite enjoyed the tinkering. I am even considering maybe splashing out on a Robert Lane regulator, but I will see how the gun performs for a while and then decide.

[j j m 6,533]

Good job mate

[Jacko338 0]

Good job big man

[The one 8,460]

Sounds like you know what your doing and will end up with a nice restored gun

[davyt63 1,845]

Well done jacko,any further help you need just pm me buddy.

don't bother wasting your air by filling to 190 bar,they seem to work best at around 160/140bar ,its where its sweet spot is.this will change by about 10/15bar between rifles

also don't be caught by filling to 190bar and putting 10 shots over a chronograph, and thinking shit its only doing 9.5ft/lbs
because if your turn the grub screw out at 190bar,and its 11.5ft/lbs, by the time rifle reaches its sweet spot it will be over.

it should be reading10.5 at 190bar as it settles on its sweet spot to about 11.5/11.7? you really need to get a 100 shot string,to find its sweet spot really.

 

also some models have a tiny grub screw beneath the bolt housing,to hold the brass shim in,undo this before removing the barrel to.

hope this helps

PS.

if you cant get the FPE over 9.5 through its shot string,then you need to make sure the firing pot needs to be screwed out.

to 56mm for .177 & 58mm for .22

Edited October 20, 2014 by davyt63

[Mister Gain 1,764]

Well done jacko,any further help you need just pm me buddy.

 

don't bother wasting your air by filling to 190 bar,they seem to work best at around 160/140bar ,its where its sweet spot is.this will change by about 10/15bar between rifles

 

also don't be caught by filling to 190bar and putting 10 shots over a chronograph, and thinking shit its only doing 9.5ft/lbs

because if your turn the grub screw out at 190bar,and its 11.5ft/lbs, by the time rifle reaches its sweet spot it will be over.

 

it should be reading10.5 at 190bar as it settles on its sweet spot to about 11.5/11.7? you really need to get a 100 shot string,to find its sweet spot really.

 

also some models have a tiny grub screw beneath the bolt housing,to hold the brass shim in,undo this before removing the barrel to.

hope this helps

 

PS.

if you cant get the FPE over 9.5 through its shot string,then you need to make sure the firing pot needs to be screwed out.

to 56mm for .177 & 58mm for .22

 

I believe your reply was aimed at me Davy

Thanks for the hints and tips, appreciate it.

The advice regarding heating the barrel was a great help.

I did find both the grub screws to remove the barrel, one for the brass bit was hiding underneath the magazine clip.

I'll set the target up tomorrow and put a load of AA Fields through it with the chrono, and see how it goes through the range down to about 130 bar.

 

I haven't actually unscrewed the cylinder yet, but have the replacement 'O' rings ready and waiting.

Also, I like the results I got in Chairgun Pro with my scope set on 8x mag with the mildots lining up pretty much bang on. The shallow trajectory should help no end with the night shooting and range estimation.