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Thread: BSA 240 Magnum modifications?

  1. #16
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    26,320
    First impressions.. much better than I expected actually..


    The good: accuracy with hobbies. 5 shots groups ranging from 1/2" - 3/4" at 8 yards, which for a lightweight spring pistol is pretty good IMHO. trigger also quite light and fairly predictable. Weight quite light, so I will probably add some mass to aid stability. A longer barrel would achieve this perfectly, but I doubt the old one will come out easily.

    The bad: not that bad really, but a little too much cocking effort, and definitely too much recoil - it wants to take off sideways and downwards. A loose grip defo needed for accuracy. Needs a softer spring / lighter piston or both.

    The weird: huge amount of sight elevation - presumably due to the downwards recoil which must be moving the muzzle way before pellet exit. Also the grips are just stupidly weird - narrow at the top where your hands are widest


    So it's all about recoil reduction (and some new grips in the future). And maybe adding a little muzzle weight.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  2. #17
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    26,320

    Did a little tune..

    Stripped her down - very easy.

    Very very dry in there.

    First thing was to chop a coil off the spring, heat, and close, and dress on the grinder. I wanted to reduce the cocking effort a little regardless, so no choice there.
    Piston washer was in good condition and a nice fit in the bore, so nothing to do there except a smear of moly on it, and on the front and tail of the piston. I contemplated lightening it at bit, but thought I'd do the basics first.
    Made a beer can piston sleeve, lubed it all up and installed
    Took a fraction off the rear spring guide OD, possibly even a smite too much, and then lubed it up and re-installed

    Last thing - the bore of the plastic block that sits at the muzzle was 6.5mm - I thought that was a bit tight for a 5.5mm pellet, sitting 2 inches from the end of the barrel, on a lively recoiling pistol - so I opened it out to 7.5mm (which just kissed the crosspin, but barely). If I decide I need some muzzle weight, I'll replace this block with steel.

    Reassembled and shot a few... cocking effort definitely reduced a bit, as is recoil. Power up from 3.5 to a very consistent 4.3 FP with hobbies, and the POI has gone up 3", which is good, as the weird recoil is dragging the POI down, so that effect has reduced.

    I think I'll just leave it like this to be honest. I could lighten the piston, but it's not at all bad right now, so it's not crying out for it. Also it might cause issues with the trigger if I trim the outside, so would prob have to mill a couple of large slots lengthways well away from the trigger - e.g. 10 o'clock and 2 o'clock.


    So there you go; not much more than a simple spit and polish is all this little beastie needs really.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

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