Results 1 to 6 of 6

Thread: Webley Senior Mainspring Sizes.

  1. #1
    Join Date
    Feb 2001
    Location
    Winchester, UK
    Posts
    15,343

    Webley Senior Mainspring Sizes.

    Just recently, a member of this BBS asked me for information regarding the length etc. of a Senior Mainspring. Unfortunately I have no drawings for this particular item, so contacted John Atkins. He supplied me with as much information as he could, along with a couple of photographs, without delving deep into his archives, as his current workload makes that task impossible. However, the information and photographs he provided are repeated on this thread with his permission.
    John has asked me to make it clear that none of the springs or other Air Gun parts he holds are available for sale.
    Most of this post is in John's own words, and many thanks to him for taking the time to pen the following.

    "It's not straightforward at all. Just as an example: ‘Senior' spring lengths varied a lot, getting shorter-and-shorter as time went by, as my photos. show, These are unused and ’new’ (apart from some being c. 85-years old!)

    The Webley ‘Senior’ officially used a 37-coil mainspring, unchanged in coil numbers since pre-war days when the Senior took over from the Mark II Target Model de luxe air pistol, which, like the Mark I used a 36-coil mainspring. The added length of the one extra coil, coupled with reduced friction of the new single phosphorous-bronze piston ring of the Senior, boosted the power from the 350 f.p.s. of the Mark I/Mark II to 360 f.p.s. in .177” calibre.

    These things are not made to an absolute standard size I have discovered. They are all over the place in sizes at different times and from different suppliers.
    Below are all genuine ‘Senior' mainsprings from different eras, the two shortest I purchased with another 2 dozen from Webley & Scott until the Senior pistol got fractionally less powerful until the spring combined as one with the Mk. I spring for the new Premier and the spring no longer had their own individual prefix and numbering of S8 (Senior); M7 (Mk. I) and M.7 (Premier) were all made the same size by then, as part no. ‘P1032’ common to all three pistols and producing a reduced 350 f.p.s. in the .177” Premier’s published data of the time.

    The longest on the 1938 box are both pre war 1930s ‘new’ unused springs The intermediate size ones are early 1950s. The power dropped as time went past until the same size spring was used for all three Mk. I Senior and Premier. This is why people putting a later spring into a Webley Senior will never achieve the same power as if an early mainspring was sourced (virt. impossible apart from my lot!)"

    John stresses the pointlessness of trying to state exact measurements for these components from different eras and different suppliers. You need to look at and compare lots of these unused, old dealers' stock, mainsprings if available - not just one someone has taken out of a rifle! If the right replacement mainspring is put in, then you shouldn’t need to start hacking bits off.

    He also asked me to include the following:

    "It’s important for me to also stress that Webley's blueprints for the MK. II Target Model De Luxe show the 36-coil mainspring at 7 inches MIN. 7.25 inches MAX. after cramping 12 hours. These items would be tested to this; so you can see that even mainsprings from the same period COULD well vary in length by up to a quarter of an inch - as I’ve always maintained - and this could affect mainsprings from the different eras creating even more variations in length to springs that had also been reduced intentionally down the years."








    Here is a copy of the 1920's Mk.11 Target Mainspring diagram taken from a barely legible original drawing. I've cleaned it up so the relevant details can be seen.

    Last edited by Troubledshooter; 14-02-2019 at 04:57 PM. Reason: Additional Info.

  2. #2
    Join Date
    Jun 2012
    Location
    North Wales
    Posts
    3,161
    Brilliant support. Thanks again.

  3. #3
    Join Date
    Jan 2017
    Location
    Pulborough
    Posts
    997
    This explains the apparent differences between Mk3 springs, which seem to vary between 210-235mm approx., according to posts on this site. Probably, in those days, producing a working air rifle/pistol was the priority, whereas consistency was a lesser issue, given the max limit was not in risk of being breached and no one possessed chronographs.

  4. #4
    Join Date
    Jan 2008
    Location
    St.Albans
    Posts
    3,217
    That was an interesting and informative read!

    Many thanks.

  5. #5
    harvey_s's Avatar
    harvey_s is offline Lost love child of David Niven and Victoria Beckham
    Join Date
    Apr 2008
    Location
    Norwich
    Posts
    9,319
    If you look at engineering drawings for even safety critical parts that were drawn well before the war you'll more often than not see the spring steel specification as "Best quality spring steel", which means that each manufacturer had their own interpretation of 'best' and manufacturing standards could be more variable too.
    Then during and just after the war steel standards went downhill over time as various alloying constituents became harder to come by....
    Little wonder they are all different.

  6. #6
    Join Date
    Feb 2001
    Location
    Winchester, UK
    Posts
    15,343
    Diagram of Mk.11 Target spring now included, plus additional information on the Senior springs, courtesy of John.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •