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Thread: Is making a delrin transfer port a bad idea?

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    Is making a delrin transfer port a bad idea?

    I have a rifle with a transfer port thats too big and making it inconsistent so need to knock up another so would one in delrin work or would it just implode with the pressure? Its only a small port about 8mm width by 10mm high with a 2mm hole

    Or should i just order some brass bar!

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    How would you make sure that such a slippery material would stay in place? The elaborate process for gluing-in delrin buttons on a piston would make me think brass would be a much simpler and more reliable answer, and one which tuners have been using for years.

    The dimensions you quote are strange! Surely a transfer port only has a diameter and a length? Unless it is some weird kind of Cardew-inspired venturi...

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    I can't see there being a problem. Our own Jim, AirGun World fame, has done so ... see this month's edition. I have also made delrin transfer ports for a pcp when experimenting a bit.
    What rifle? Just curious as 2mm is quite small. It sounds as if your current port is removeable.. or is 8mm the width of a recess?
    Cheers, Phil

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    I'd suggest you'd need to clarify how the TP seals. If o rings are present around the TP then delrin should be fine as said above.
    I've worked on some rifle where O rings have in effect been the TP. When crushed via breech and cylinder mating together, they can distort and reduce air flow. In these situations a harder less compressible (but still sealable) material is needed.
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    Quote Originally Posted by Hsing-ee View Post
    How would you make sure that such a slippery material would stay in place? The elaborate process for gluing-in delrin buttons on a piston would make me think brass would be a much simpler and more reliable answer, and one which tuners have been using for years.

    The dimensions you quote are strange! Surely a transfer port only has a diameter and a length? Unless it is some weird kind of Cardew-inspired venturi...
    The transfer port on BSA Ultra , r10 etc is roughly as the op decribes though not those dimensions. Its in effect a brass tube set between the cylinder and breech and sealed by O rings. Though I do get what you mean in that the transfer port is just the "hole" that the air passes through. A TP on a springer is basically a hole of a length and a diameter drilled in the end of the cylinder
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    Quote Originally Posted by robs5230 View Post
    The transfer port on BSA Ultra , r10 etc is roughly as the op decribes though not those dimensions. Its in effect a brass tube set between the cylinder and breech and sealed by O rings. Though I do get what you mean in that the transfer port is just the "hole" that the air passes through. A TP on a springer is basically a hole of a length and a diameter drilled in the end of the cylinder
    fort you ment a SPRINGER........ apologies...

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    In a springer I have heard that the temperature generated in the TP is very high, if this is true then a delrin TP would not be suitable.

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    Given the dimensions Barry, the OP seems to be referring to a tp on a pcp, co2 rifle
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    Quote Originally Posted by robs5230 View Post
    Given the dimensions Barry, the OP seems to be referring to a tp on a pcp, co2 rifle
    Thanks for clarifying

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    Its on a stalker rifle that I am re building, it has x2 o rings on the port top and bottom and the measurements are just a guess as its at home and I am at work currently. I found now the original .22 port size was 2.5mm so will try that first. the only thing is that its a .25 so bit unsure of size to go with for a 12flb rifle.
    I have a delrin rod spare form another project that would be perfect for the port and might need a few making of differing sizes to get the power right.
    If it works its going to be my 10 yard squirrel gun!

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    Quote Originally Posted by rovercoupe View Post
    the only thing is that its a .25 so bit unsure of size to go with to get the power right.
    If it works its going to be my 10 yard squirrel gun!
    Any squirrel that big will need a .338 Lapau Magnum at least, maybe even a .50 BMG.

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    Quote Originally Posted by rovercoupe View Post
    Its on a stalker rifle that I am re building, it has x2 o rings on the port top and bottom and the measurements are just a guess as its at home and I am at work currently. I found now the original .22 port size was 2.5mm so will try that first. the only thing is that its a .25 so bit unsure of size to go with for a 12flb rifle.
    I have a delrin rod spare form another project that would be perfect for the port and might need a few making of differing sizes to get the power right.
    If it works its going to be my 10 yard squirrel gun!
    delrin should work fine
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    I would make the part out of metal myself. Brass, mild steel and aluminum are much easier to machine accurately as plastics tend to soften due to the heat produced by machining and a lot of plastics are too elastic and holes drilled in them are smaller than the drill.
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    Quote Originally Posted by Phil Russell View Post
    I can't see there being a problem. Our own Jim, AirGun World fame, has done so ... see this month's edition. I have also made delrin transfer ports for a pcp when experimenting a bit.

    Cheers, Phil
    Quote Originally Posted by Barryg View Post
    In a springer I have heard that the temperature generated in the TP is very high, if this is true then a delrin TP would not be suitable.
    Okay, slightly off at a tangent, as it's not a springer that the OP is referring to, but, Barry, as Phil says above, Jim's been playing with acetal transfer ports on TXs. All good. And that silly high temperature is only generated for a miniscule amount of time meaning no ill effects with the synthetic TP.
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    Hopefully here is a pic of the port in question,

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