Transfer Port Screw Adjustment

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deadeyeddick
Posts: 13
Joined: Mon Apr 03, 2017 11:27 am

Transfer Port Screw Adjustment

Wed Mar 20, 2019 7:24 pm

I recently had an s510 in .22 serviced by an RFD. I requested that he left the AT off so that I could fine adjust the output in relation to each selection of pellets. I weigh all my pellets into batches from each tin. I have currently set the output to 11.8 lbs using AA Diablo Field Heavy. The heaviest weighed 18.1 gn. Could I ask. Is it wrong to keep adjusting this screw for the purpose of fine tuning as intended. Is it also possible for the adjustment screw to become dislodged if adjusted too far out. Although I assume the 12 ft legal limit would be breeched before this.

I know if I adjust it too far the gun will go over 12 ft and become a firearm. This is not my intention.

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TenMetrePeter
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Location: Luton Beds UK

Re: Transfer Port Screw Adjustment

Wed Mar 20, 2019 8:21 pm

My opinion is firstly replace the cover with a M3 x 6 screw because the adjustment screw is not fully air tight.
A security keyed Torx screw allows you to take the gun out into the field effectively tamper proof. You don't want a law officer to find you sitting in the field with an allen key sticking out the screw hole.
Secondly the main problem is that the PVC friction patch can become loose with wear so buy a couple more adjuster screws from bgaltd.
Some suggest adding a second grub screw above the main one to lock it but I found it did not lock, rather it disturbed the adjustment.
I have a low power 6ftlb MPR so it may not be the same, but I found adjustment was very sensitive and half a turn can make a large change.

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deadeyeddick
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Re: Transfer Port Screw Adjustment

Wed Mar 20, 2019 9:06 pm

Hi many thanks for your reply. Very interesting. The RFD did fit a allen key headed cover screw which covers the adjustment whole to the transfer port adjustment. Can the adjustment screw on the transferred port be removed by just unscrewing it. What is the PVC friction patches and how do you go about replacing them.

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tonyc
Posts: 376
Joined: Mon May 29, 2017 10:55 am

Re: Transfer Port Screw Adjustment

Wed Mar 20, 2019 9:25 pm

A further suggestion, if you feel up to it!
If you reduce the pre-load on the firing valve spring you can restrict the maximum power to below 12ft lb when the transfer port is unrestricted. To do this you will need to de-pressurise the cylinder and unscrew it from the action. Then unscrew the valve housing a little (try 1/2 turn) and reassemble. Fill to 130 bar and check the power. You may need to repeat the process a few times to get it right but you will then have a gun which, barring disassembly, is not capable of going over the limit.

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deadeyeddick
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Re: Transfer Port Screw Adjustment

Wed Mar 20, 2019 10:00 pm

How can I contact bgaltd.

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TenMetrePeter
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Joined: Wed Jun 29, 2016 5:40 pm
Location: Luton Beds UK

Re: Transfer Port Screw Adjustment

Wed Mar 20, 2019 11:22 pm

deadeyeddick wrote:
Wed Mar 20, 2019 10:00 pm
How can I contact bgaltd.
https://www.airarmsspares.com

Or send PM to forum member bgaltd

The pvc patch is welded to the adjustment screw so you replace the screw itself. Its a bit like pre-applied Loctite.
Just screw it right out. You might want to first screw it right in, counting the turns so you can put it back roughly as it was.

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deadeyeddick
Posts: 13
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Re: Transfer Port Screw Adjustment

Thu Mar 21, 2019 8:09 am

Hi Peter . Sorry for being so thick, but I assume from you response the adjustment screw can be unscrewed and removed via the access hole without stripping the gun down.

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TenMetrePeter
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Location: Luton Beds UK

Re: Transfer Port Screw Adjustment

Thu Mar 21, 2019 8:36 am

deadeyeddick wrote:
Thu Mar 21, 2019 8:09 am
Hi Peter . Sorry for being so thick, but I assume from you response the adjustment screw can be unscrewed and removed via the access hole without stripping the gun down.
Yes.

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tonyc
Posts: 376
Joined: Mon May 29, 2017 10:55 am

Re: Transfer Port Screw Adjustment

Thu Mar 21, 2019 5:24 pm

TenMetrePeter wrote:
Wed Mar 20, 2019 11:22 pm
Just screw it right out. You might want to first screw it right in, counting the turns so you can put it back roughly as it was.
Peter, do you know the dimension or how many turns are required for the transfer port to be fully un-restricted? I wondered if there is an easy way of setting this in conjunction with backing off the pot to cap maximum power. If the screw is unwound too far it's going to increase the dead volume of the transfer port, reducing efficiency, which is what I want to avoid. Otherwise it's a matter of trial and error - simple enough provided there is minimal interdependency between valve setting and free flow through the transfer port. At the moment I have the venturi screw well back - possibly too far.

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Roger5
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Location: Hampton middlesex

Re: Transfer Port Screw Adjustment

Thu Mar 21, 2019 6:04 pm

tonyc wrote:
Thu Mar 21, 2019 5:24 pm
TenMetrePeter wrote:
Wed Mar 20, 2019 11:22 pm
Just screw it right out. You might want to first screw it right in, counting the turns so you can put it back roughly as it was.
Peter, do you know the dimension or how many turns are required for the transfer port to be fully un-restricted? I wondered if there is an easy way of setting this in conjunction with backing off the pot to cap maximum power. If the screw is unwound too far it's going to increase the dead volume of the transfer port, reducing efficiency, which is what I want to avoid. Otherwise it's a matter of trial and error - simple enough provided there is minimal interdependency between valve setting and free flow through the transfer port. At the moment I have the venturi screw well back - possibly too far.
Same as the pellet in the barrel thing really, while it's apart, look down the transfer port, you can see the PAS

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