Best way to change a breech seal on a S400F?

[Cal50]

I recently acquired a lovely s400f Superlite. Shoots lovely but chronographed at 9.5ft/lb. I'm sure there's a knack to it but what is the best way to change the breech seal, get old one out and new in? 

It looks very worn so I'm hoping that's the cause of the power lose. I've ordered a full kit with hammer spring to so if it's still a shade low I'll look at swapping that out. Thanks for any hello in advance 👍

[Mice!]

@Biffo1262 has commented on doing a reseal on a 410 on the other thread,  always best to start on YouTube and watch how it's done to see if its something you think you can do.

[oldypigeonpopper]

Hello, a breech seal is very easy to change, I use a dentist kit off eBay, pick, tweezers, mirror, a torch is handy, take out old seal with pick, get some wood dowl cut length just before seal groove from muzzle end, spray oil in breach, use tweezers to place new seal in breach but carefully , use dowl to stop going in to far and new seal should pop in groove, push loading bolt forward to make sure seal is set in groove, the 400 should be around 10.5 to 11.5 ft llb, try the new breach seal but if no change you might want to get it serviced, AA PCPs go on working for years if looked after, phone AA with serial number so you know date of manufacture, they also service their air rifles , based in East Sussex 

Edited September 18, 2023 by oldypigeonpopper

[oldypigeonpopper]

13 minutes ago, oldypigeonpopper said:

Hello, a breech seal is very easy to change, I use a dentist kit off eBay, pick, tweezers, mirror, a torch is handy, take out old seal with pick, get some wood dowl cut length just before seal groove from muzzle end, spray oil in breach, use tweezers to place new seal in breach but carefully , use dowl to stop going in to far and new seal should pop in groove, push loading bolt forward to make sure seal is set in groove, the 400 should be around 10.5 to 11.5 ft llb, try the new breach seal but if no change you might want to get it serviced, AA PCPs go on working for years if looked after, phone AA with serial number so you know date of manufacture, they also service their air rifles , based in East Sussex 

You do not say where you are located ??

[Cal50]

38 minutes ago, Mice! said:

@Biffo1262 has commented on doing a reseal on a 410 on the other thread,  always best to start on YouTube and watch how it's done to see if its something you think you can do.

I'm happy I can do it. Just looking for advice on the easiest way to go at it in people experience. There's no good videos on YouTube that I've seen unfortunately.

[Mice!]

3 minutes ago, Cal50 said:

I'm happy I can do it. Just looking for advice on the easiest way to go at it in people experience. There's no good videos on YouTube that I've seen unfortunately.

Have a look if XTX have done a video,  his videos for BSA rifles are brilliant 

[Cal50]

22 minutes ago, oldypigeonpopper said:

Hello, a breech seal is very easy to change, I use a dentist kit off eBay, pick, tweezers, mirror, a torch is handy, take out old seal with pick, get some wood dowl cut length just before seal groove from muzzle end, spray oil in breach, use tweezers to place new seal in breach but carefully , use dowl to stop going in to far and new seal should pop in groove, push loading bolt forward to make sure seal is set in groove, the 400 should be around 10.5 to 11.5 ft llb, try the new breach seal but if no change you might want to get it serviced, AA PCPs go on working for years if looked after, phone AA with serial number so you know date of manufacture, they also service their air rifles , based in East Sussex 

The dowl idea is a good one but that's a very long thin length of wood I'd need to find. 

I'm sure I have a dentist pick somewhere so that should do the job. I might just see if with a bit of patience and care I can gently get it in without the dowl.

I've ordered full seal kit so will probably service it myself in a few months as I'm considering fitting a regulator.

1 minute ago, Mice! said:

Have a look if XTX have done a video,  his videos for BSA rifles are brilliant 

Ok will do thanks, I've also got a scorpion se I'll be doing soon aswell as that's lost a ft/lb over the last few years.

[Biffo1262]

On 18/09/2023 at 09:54, oldypigeonpopper said:

Hello, a breech seal is very easy to change, I use a dentist kit off eBay, pick, tweezers, mirror, a torch is handy, take out old seal with pick, get some wood dowl cut length just before seal groove from muzzle end, spray oil in breach, use tweezers to place new seal in breach but carefully , use dowl to stop going in to far and new seal should pop in groove, push loading bolt forward to make sure seal is set in groove, the 400 should be around 10.5 to 11.5 ft llb, try the new breach seal but if no change you might want to get it serviced, AA PCPs go on working for years if looked after, phone AA with serial number so you know date of manufacture, they also service their air rifles , based in East Sussex 

Yes, a set of O ring picks is essential.  Removing it is pretty simple but getting the new one to seat can be a PITA until.....I realised if if I pushed a pellet in by hand to the far part of the of the O ring seat and VOILA!  A doddle.  It just replaces the dowel.

Edited September 19, 2023 by Biffo1262
Spelling as usual.

[222mark]

Placing a piece of tissue paper over the bolt when you fire it will show you if the breech seal is leaking. Obviousley with a pellet in. The tissue will move if any air is being blown back.

[DUNKS]

Oh and be careful ferreting around with a dental pick. It's a harder material than your barrel

[Cal50]

18 hours ago, Biffo1262 said:

Yes, a set of O ring picks is essential.  Removing it is pretty simple but getting the new one to seat can be a PITA until.....I realised if if I pushed a pellet in by hand to the far part of the of the O ring seat and VOILA!  A doddle.  It just replaces the dowel.

Brilliant idea Thanks 👍

[Biffo1262]

It took me years to think of it and then it was a case of 'slaps forehead' it was so simple. 🤣

[bruno22rf]

On 20/09/2023 at 09:19, 222mark said:

Placing a piece of tissue paper over the bolt when you fire it will show you if the breech seal is leaking. Obviousley with a pellet in. The tissue will move if any air is being blown back.

Why not use Talcum powder - far more sensitive and easier to see.

[snarepeg]

I found a. Pellet pushed in fraction past seal helps getting the new one in, push it back with a rod if needs be.

as said a thin sharp instrument to hook old one out.

[Andy 01]

Same.
I use a flat head pellet pushed in backwards.
That gives you a flat surface to work against.
I can change one in seconds that way 🙂 

Andy