S400 problem

[matgriff]

I've had my AA S400 for a number of years now, it's in great condition, well looked after and I serviced it with a new seal kit about 12 months ago. I also have the Rowan 10 shot mag.

Just recently I've noticed two problems, maybe connected ? First is that the pellet loading bolt is getting jammed as it tries to push the pellet into the breech. The pellet seems to cock down at a slight angle as it slides to the end of the little guide shoe that comes withthe Rowan mag kit, and then its at a angle as it tries to enter the brass part of the breech. Something's changed as it's been fine for 5 years or so.

Also I've noticed that I'm feeling a small puff of escaping air when I shoot, I can feel it on my face/eyes.

I've stripped the gun down, everthing seal wise looks OK. The pellet loading issue must be mechanical, but I just can't work out why the pellets are not loading straight into the breech...

Any ideas ?

Thanks


Mat

[Roger5]

Hi Mat, just wondering, have you changed the pellet, or maybe a different size 4.51/4.52
My S400 also uses the little lifter to align the pellet ,what I noticed a while ago is that some pellets don't drop from the mag as they should do , the bolt then catches the bottom of the pellet causing damage as you push the bolt home, this can then cause jams. Air coming back at you when firing can be breech seal or depending on age of rifle the transfer port seal either leaking or gone missing. Rog

[matgriff]

Hi Rog...thanks for the reply.

I have started using JSB heavy pellets, presiously was using JSB exact diabalo .177. It's been ok with the heavy and I also tried the diabalo and it's the same. I notice it just as the bolt gets to it's final travel, its started to jam, and on closer inspection when I removed the scope, I can see that the pellets are being pushed along by the bolt, then just before they enter the brass part of the breech they cant off centre slightly, nose down, and the bolt's not pushing them square into the breech, it's a bit odd.

Regarding the transfer port seal, looking at the pics online I have the wrong one fitted, mine is really thin, the one's I've seen online look quite thick, I read it should be 6 x 1 mm, I'll measure mine with my vernier but it looks much less. I must have fitted the wrong one from the kit I got last year. Is there another one in the kit for a different place that's thinner ? maybe I mixed them up.

Probably time for a full strip down & clean and re-seal.

Thanks

Mat

[Roger5]

S427 is standard transfer port seal, there's 2 in the seal kit, one is also used on the gauge mount bolt, and it is the thin one
The fat one is S536 it goes on the gauge mount bolt, what year is your rifle? Rog

[matgriff]

Rifle is 2005. I definitely have the wrong transfer port seal, because the o/d is 7.5mm approx and the thickness is 0.8, weird because I still have the kit and the little bags with the part numbers on, although the photocopy sheet with the pictures is a bit tricky to follow, as they seem slightly different when overlayed.

I've now found the problem with the pellet loading.. although I need to look much closer on why. But it seems that the problem is that when the pellet reaches the start of the brass entrance to the breech block, it's loose, and before it enters the start of the barrel it moves off center, so the pellet and the barrel are missaligned somehow ?? difficult to explain without a photo. From what I can see the transfer port is slightly missaligned to the hole in that brass insert ? also, when aligning the actual barrel, there's a small hole in the brass collar, is that supposed to align with the small hole just before the transfer port ?

I need to look at the you tube video again to make sure I've got everthing correct.

Mat

[matgriff]

OK I figured it all out.... my breach seal has gone AWOL

So I guess that's why the pellet is moving off center, the nose is dropping into the little groove where the seal sits, and also why I can feel air escaping when I shoot... though the two must somehow be related.

Thanks for the advice Rog.

Not sure how that seal went missing, maybe got nicked by a pellet loading and then got pushed into the barrel

Think I'll buy a few spares along with the transfer port seals.


Mat

[Roger5]

The seal holder in the bolt Housing needs to align with the transfer port hole, if it doesn't, it will restrict the airflow to the pellet.
As you have the older Rifle , you could possibly get away with useing a slightly larger seal for the TP seal, not always possible on the later ones, as the bolt configuration changed i.e. A/A moved the 2 bolts which were in front of the TP seal , in doing so all that holds the seal is the bolt Housing pushing down onto it, and if you use a larger seal on these later rifles, it will lift the front of the bolt Housing , you would then have to push the barrel down to refit the barrel band.
This is the reason I only have the older ones myself, I'll stop now as you're probably dozing off LOL

[Roger5]

Nice one Mat, glad you sorted it Rog

[matgriff]

Hi Rog, yes OK understood Re the position of the screws on the block that clamp the TP seal.

I see it's possible to get a delrin plastic TP seal washer ? are these any good ?

Also, should there be any O ring on the barrel itself where it slides into the housing block ? I don't have one on mine, but there appears to be a groove recess that look like it should have a seal ?


Mat

[Roger5]

I know about the TPseals that you refer to, haven't used them myself, but as long as you have the early rifle up to about 2009/10 could be ok, chap on here (archer80 based in Perth) used them, can't remember which Rifle on though.
Seal on barrel, my understanding is that some have them and some don't, might be an idea to ask Julian, airarmsspares.com, he'll know Rog