S410 Low Power Problem

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Portland_Jon
Posts: 4
Joined: Thu May 06, 2021 6:37 pm

S410 Low Power Problem

Mon Aug 16, 2021 5:12 pm

Hi all. I'm tearing what little hair I have left out with this S410. It's a .22 carbine and very well used that my friend asked me to look at as it was leaking on the firing valve. I sorted that out but it was inconsistent so I gave it a full rebuild. It's now had a new firing valve and pin, both springs and all new o-rings. I just can't get the power back up to where it should be. It just won't go above 530fps with JSB's when it should be 580ish.

I phoned Julian last week and he said to clean everything which I've done. The hammer shaft is polished to a mirror finish and the hammer has almost zero friction but I'm lost for ldeas. Anyone got any suggestions please?

Jon

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Portland_Jon
Posts: 4
Joined: Thu May 06, 2021 6:37 pm

Re: S410 Low Power Problem

Tue Aug 17, 2021 8:41 am

I'll have a look in a bit but I remember thinking that the hole in the back of the firing pot was too small. It's smaller than the transfer port so it's likely to be the problem.

Jon

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Roger5
Posts: 1071
Joined: Sat Jul 25, 2015 8:04 am
Location: Hampton middlesex

Re: S410 Low Power Problem

Tue Aug 17, 2021 9:10 am

What's the year ?

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Roger5
Posts: 1071
Joined: Sat Jul 25, 2015 8:04 am
Location: Hampton middlesex

Re: S410 Low Power Problem

Tue Aug 17, 2021 9:25 am

Ok, what did you set the firing valve at ?
Have you inadvertently blocked the transfer port when refitting the seal ?

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Blackbaronfish
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Location: Nuneaton

Re: S410 Low Power Problem

Tue Aug 17, 2021 10:32 am

Is the transfer o’ring still in place.

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

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Roger5
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Joined: Sat Jul 25, 2015 8:04 am
Location: Hampton middlesex

Re: S410 Low Power Problem

Tue Aug 17, 2021 10:41 am

Leave the hole in the pot alone
And what pressure are you filling to when you chrono it ?

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Portland_Jon
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Joined: Thu May 06, 2021 6:37 pm

Re: S410 Low Power Problem

Tue Aug 17, 2021 2:47 pm

I took the hole in the pot out to 4.6mm and set it at 57mm protruding. Filled the reservoir to 150bar and still only making 530fps with JSB'S.

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Portland_Jon
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Joined: Thu May 06, 2021 6:37 pm

Re: S410 Low Power Problem

Tue Aug 17, 2021 4:34 pm

An update. I discovered that the hammer spring spacer (W263) was missing and I couldn't find it. I made one on the lathe and inserted it and it went up to 560ish. That's in the ball park but before I changed the firing valve it easily made the limit. The only simple thing that I can think of is that I don't have the correct transfer port o-ring and am using a set that I have which I think are too thick and may be covering the port when compressed.

Jon

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Roger5
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Joined: Sat Jul 25, 2015 8:04 am
Location: Hampton middlesex

Re: S410 Low Power Problem

Wed Aug 18, 2021 7:32 am

S427 is the transfer port seal,
My S410 .22 is running at 565fps 11.36ftlb with AADF5.52 16gn
That's at about 130bar, well enough

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