1. The Forum Rules have undergone some minor changes and updates.  Please take the time to read them; it will only take a couple of minutes of your time. By doing so, you lessen the chance of incurring the wrath of the moderation team or making yourself look foolish to other members.

    90% of users posting adverts in the Sales forums need to be reminded to read the rules as their posts are wrong.  This is unnecessarily time-consuming and will no longer happen - if your advert doesn't follow the Sales Rules it will be deleted and you'll have to start all over again.

    To close this box once you've read it (and the Rules), click on the X in the top right-hand corner.

    Thank you.

    AGF Staff



    Dismiss Notice
  2. A reminder of one of the Forum Rules:

    'Behaviour

    Do not make inappropriate or offensive posts - including threats, harassment, swearing, prejudice, defamation, deliberate insults or name-calling, other negative remarks about this forum, its moderators and administrators or your fellow members. Even if this is just your own personal opinion, RESPECT YOUR FELLOW MEMBERS.'

    There have been changes made to our censoring software in an attempt to help with this growing problem.

    Click the X in the top-right-hand corner to dismiss this notice.
    Dismiss Notice
  3. Dear members,

    Our membership (like our country) consists of people from all walks of life; different in far more ways than can be listed here and each with a different view based on their experience of life - regardless of their colour, religion or cultural heritage. Every single person in the UK has been born of mixed race – we are a multi-coloured and multi-cultural country.

    As many of you are aware there are a handful of individuals amongst this membership that persist in making provocative, inflammatory, racist and otherwise offensive comments. This has been happening across the forum to a certain degree but is most especially prevalent in the Adult section.

    The moderation team has tried to stay on top of this, however unfortunately because of the ‘offensive’ nature of much of its content we don’t monitor the Adult section quite as much as perhaps we should. As a result much of this behaviour has gone unnoticed unless it has been reported to us. While the team always intended to take a "light touch" approach to the Adult section it would seem that some people aren’t quite adult enough to be left unmonitored after all.

    This behaviour is, and always has been against Forum Rules as well as the specific stipulations of the Adults forum and it will no longer be tolerated. We feel it's time to draw a line in the sand and as such from this point onward offenders will receive an immediate and permanent ban from the forum.

    In order for us to achieve our goal of restoring the forum to the friendly and tolerant place it once was, we ask that ALL members be mindful of the content they post and help us to stop unacceptable behaviour by using the 'Report' tool at the bottom of any offending post - the results of which can be seen only by Admin/Moderators.

    You should all receive a copy of this message by PM. 

    To close this message box, click on the 'X' in the top-right-hand corner.

    Dismiss Notice
  4. Hotmail block emails from us entering your inbox. Unless you can setup a safe sender you will not get activation emails from the forum. Please use an alternative provider or complain to Hotmail.
    Hotmail addresses include.

    @Hotmail.co.uk @Hotmail.com @outlook.com @Live.com
    Dismiss Notice
  5. Postings on Politics, Religion & Controversial Off-Topic Material

    The majority of users do not want to read about these subjects and people have left the forum as a result of it – this is after all an 'Airgun' Forum. It’s all very well to say they don’t have to read it if they don't want to, but as most of us use the ‘New Posts’ button there is no easy way to avoid it.

    All AGF staff members are in favour of people being able to discuss what they want, but we have to draw the line somewhere if it is upsetting other users. We don’t want to read about these topics either.

    IMPORTANT- The discussion of politics and religion is no longer allowed anywhere on the forum (including the Adult section).  The only exception is if it's airgun related - they must be put in the Airgun Related Politics section..

    We will not tolerate bullying or personal attacks, racism or any other offensive 'isms'. we will remove these topics from the forum, we will not give you an area where you can abuse each other. We will not hesitate to ban offenders.

    To clear this text box, click on the 'X' in the top right-hand corner.

    Dismiss Notice

Airsporter piston head

Discussion in 'Anything Airgun Related' started by Meteor62, Mar 7, 2014.

  1. Meteor62

    Meteor62 Major Poster

    Messages:
    9,024
    Likes Received:
    1,752
    Location:
    Coventry
    Don't look right to me somehow?
    [​IMG]
     
  2. Jackroadkill

    Jackroadkill Donator

    Messages:
    16,783
    Likes Received:
    97
    Location:
    Drenewydd, Powys, Cymru
    Hmmm, looks a bit odd.

    Mine looks like this:

    [​IMG]

    Is yours some sort of custom job?
     
  3. Meteor62

    Meteor62 Major Poster

    Messages:
    9,024
    Likes Received:
    1,752
    Location:
    Coventry
    Think mine maybe oversized?

    There's a possibility it's been modded to keep the power under 6 ft lb. however I'm not sure what the actual length of the piston head is on a standard airsporter .
     
    Last edited by a moderator: Mar 7, 2014
  4. oliver13

    oliver13 Donator

    Messages:
    1,149
    Likes Received:
    1
    Location:
    Lairg
    I would say it it is oversized, maybe 6mm too long?

    Normally the piston stops just after the 'O' ring, as said must be some kind of custom job - I've no idea what advantage an extra groove with a circlip thing is supposed to give - I would have thought it would be a handicap with a shortened stroke & as it stands, lost volume.

    Here's a link to a picture of a normal plastic one:
    http://www.airgunspares.com/store/product/6741/BSA-Airsporter-Piston-Head-Part-No.-16-2331P/
     
  5. Meteor62

    Meteor62 Major Poster

    Messages:
    9,024
    Likes Received:
    1,752
    Location:
    Coventry
    The theory is it was a bell target gun and the extra piston length is to keep the power down to its current sub 6 ft lb. my next question is how does this head come off as I see no retaining pin.
     
  6. Patrick

    Patrick Donator

    Messages:
    11,748
    Likes Received:
    3,925
    Location:
    Wiltshire
    BSA did use a nylon piston head with a wire piston ring in their Airsporters & Mecurys during the 1970's.I bought a new Mecury,my first air rifle,in about 1976 and that had the nylon head with metal ring.I think BSA went over to the aluminium head shortly after because the nylon head used to expand and become a tight fit in the bore.I've actually got a PTFE HEAD that takes an 'O' Ring seal as well if anyone wants it
     
  7. oliver13

    oliver13 Donator

    Messages:
    1,149
    Likes Received:
    1
    Location:
    Lairg
    I've just had a look on Chamber's & the Mk4 & 5 do appear to have that piston head, I've never seen one before, I still don't understand why it's like that, but there it is.
     
  8. Johnc61

    Johnc61 Donator

    Messages:
    560
    Likes Received:
    12
    Location:
    Fareham, Hampshire
    Have to agree, it looks homemade to me. Google Airsporter piston head and look at the images. All are double grooved for buffer washer and o ring, not triple grooved with a wire ring. Many different materials but none like that, and the finish looks rough. Probably someone experimenting with it.
     
  9. Meteor62

    Meteor62 Major Poster

    Messages:
    9,024
    Likes Received:
    1,752
    Location:
    Coventry
    [​IMG]
    Looking at this braising is this normal or has someone had a tinker?
     
  10. Meteor62

    Meteor62 Major Poster

    Messages:
    9,024
    Likes Received:
    1,752
    Location:
    Coventry
    Took the head off it now
    [​IMG]
    Ordered one of those terry Robb jobs
     
  11. Johnc61

    Johnc61 Donator

    Messages:
    560
    Likes Received:
    12
    Location:
    Fareham, Hampshire
  12. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

    Messages:
    20,170
    Likes Received:
    24,190
    Location:
    Oxfordshire
    From what I've been told the piston head (and superflous "scraper" ring) are standard for rifles of that age. Probably worth replacing the head with a shorter ally one; this should lengthen the stroke by a few mm too.

    As for the brazing; I'm not sure how they were supposed to be fixed, but given the state of some of the (untouched) BSAs I've seen in the past not a lot would surprise me tbh :rolleyes:
     
    Last edited: Mar 7, 2014
  13. Jackroadkill

    Jackroadkill Donator

    Messages:
    16,783
    Likes Received:
    97
    Location:
    Drenewydd, Powys, Cymru
    The brazing's similar to what I found on mine, if that's any help.
     
  14. Meteor62

    Meteor62 Major Poster

    Messages:
    9,024
    Likes Received:
    1,752
    Location:
    Coventry
    [​IMG]
    Took the head off and ordered a tr Robb one
     
  15. T 20

    T 20 Busy Member

    Messages:
    882
    Likes Received:
    54
    Location:
    I'm over here, Dave
    It all looks standard early 1970s BSA, slightly later guns did away with the steel circlip, then after that the O ring was moved forward.



    All the best Mick
     
  16. oliver13

    oliver13 Donator

    Messages:
    1,149
    Likes Received:
    1
    Location:
    Lairg
    If you look at the diagram from Chamber's it's pretty clear this was the type of piston head used: https://www.gunspares.co.uk/products/24687/Mk5/

    If you substitute a newer one the locating rod should be the right size, the pistons have identical part no's, but you may want to consider fitting it without a buffer washer, in which case the hole for the locating pin will need to be redrilled further back. It's supposed to give a little more power but I've left all mine are in original configuration.
     
  17. Patrick

    Patrick Donator

    Messages:
    11,748
    Likes Received:
    3,925
    Location:
    Wiltshire
    The PTFE piston head I have was made by T R Robb, never fitted though as I changed rifles but I still have it,it's never been used so if anyone wants it message me The brazing looks fairly normal it's how the pistons were made at the factory
     
    Last edited: Mar 8, 2014

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice