BSA 240 Magnum - the way it should have been.

[thoro]

I bought my first BSA 240 Magnum 20 years ago on a whim. 510fps advertised muzzle velocity (.177) in a compact pistol sounded good on paper and I could see all kinds of applications; target shooting, plinking and more. The one I bought actually lived up to the hype with a velocity of 520fps with Hobbies…if only the practical accuracy had been as good. Initial sub-4 inch groups and it took a couple of hours to consistently hit a coke can at 10 yards. I practised a lot and the groups became tighter but never truly good in spite of a good trigger. It was incredibly hold sensitive and the recoil was very harsh due to the low weight of the pistol.
A few years later I noticed one day that the velocity had dropped to less than 300fps. It turned out that one of the weak points of this gun is the breech seal (another is the overlever catch). Had the breech replaced and the power went up a bit, though not to 520fps. Took it back to the shop but they only managed to bring it up to 460fps.

They kindly offered to replace the gun with a new one and I even got to pick the best of the ones they had in stock, which is the one I still have. 505fps so slightly less power than the first one, but far better than the others they had in stock, which only managed 460-470fps. This seems to be the norm for this gun in cal. 0.177 rather than the advertised and much hyped 510fps.
The second Magnum still kicked like a mule but I enjoyed it for informal plinking sessions and could get decent groups on a good day, albeit always with one or two fliers.
I then did very little shooting for several years and only recently took it out, only to find that the hiatus had not been kind to it. Chronied it and got about 460fps with 7 grain Gamos (similar to the Hobbies in weight).

Clarky did a stellar job with my Walther LP-53 so asked him if he was willing to take a look at the Magnum too, which he was. My initial expectations were only to get as much of the power back as possible and perhaps reduce the recoil a bit. I have been in contact with gunsmiths who refuse to work on this gun as it is rather challenging to get it right, but after what I had seen what he did with the Walther I had confidence in Clarky’s abilities.
He explained in details some of the design flaws of the gun; square spring guide rod, 90 degree transfer port design and possibly also too short barrel in order to give room for the plenum. The last two were not possible to tweak or change, but he started by designing a completely new spring guide for it. The next step was adding a piston weights, gram by gram. Assembly and disassembly, then test it with an added 2 grams until that point of tail off in velocity – very time-consuming. The mainspring was in good condition and they usually last a long time. The piston seal was changed as it was on its way out anyway and the cost is low.

All along Clarky provided a clear description of the work carried out – his approach was methodical and meticulous and it was clear he has both the theoretical knowledge and practical skills for this task. He returned the pistol in less than a week and advised that the new seal will have a run in period of 300-400 pellets or so.
As with the Walther, the returned gun looked like a standard Magnum but it during my first session it was clear that this was anything but a standard Magnum. The secondary recoil (piston bounce) was essentially gone and accuracy was improved by at least 50 percent. The twang was gone and the gun felt solid and powerful . I ran a test in the weekend with RWS Meisterkugeln, Falcons and AA’s blue express on target at 8 yards distance and managed 1 ½ inch groups with all of them and only 1 or 2 fliers. It is still hold sensitive and I need to practise more but this gun is clearly in a different league than the standard gun.

I then ran all three pellet types through the chrony:

Meisterkugeln:
499.7 fps low
508.2 fps high
505.2 fps average

Falcons:
487.2 fps low
491.5 fps high
490.2 fps average

AA:
472.4 fps low
479.3 fps high
476.0 fps average

The power and accuracy of this pistol is now what it could and should have been when launched. One cannot help but think how different things could have been, had this been the finished product in the mid-1990’s. Add a longer barrel and better grips and it could have been a serious competitor to the HW45, which I find fatiguing during long sessions due to its weight. Instead it disappeared from the market after 5-6 years and is now becoming collectable.

It is a flawed design but for reasons hard to explain I always enjoyed shooting this pistol in spite of its shortcomings.
Thanks to Clarky most of these shortcomings are now gone and it is a real treat to shoot. I am very grateful for the workmanship, time and dedication that went into this tuning and looking forward to tighten these groups even more now.
Cheers

Tom