BSA 240 Magnum modifications?

[Nikkormat]

I bought a .22 BSA 240 Magnum back in 1996, with either my first or second pay packet. I think it was the second variant, with a slightly redesigned grip.

It looked far better than the HW45 lump, and was generally very well engineered, I thought. I never had the problems with the breech seal I've since read about.

It was powerful enough, but for the life of me I couldn't shoot it consistently. It seems I was not alone in this; posters on here have mentioned it being too light for its power and a barrel too short to be efficient.

So... has anyone modified one and tamed it? I am thinking maybe a longer barrel (taking up the inch or so void in the frame) and maybe some added weight?

Matt

[flatrajectory]

I bought a .22 BSA 240 Magnum back in 1996, with either my first or second pay packet. I think it was the second variant, with a slightly redesigned grip.

It looked far better than the HW45 lump, and was generally very well engineered, I thought. I never had the problems with the breech seal I've since read about.

It was powerful enough, but for the life of me I couldn't shoot it consistently. It seems I was not alone in this; posters on here have mentioned it being too light for its power and a barrel too short to be efficient.

So... has anyone modified one and tamed it? I am thinking maybe a longer barrel (taking up the inch or so void in the frame) and maybe some added weight?

Matt

Matt,
I had the same problem. I re-profiled the grips at the top using a dremel drill ,where the knuckles of your thumb and index finger of your shooting hand tend to rub into the grip.
I added weight to the inside of the grip by drilling two holes and filling them with melted down lead pellets.
then just a smoothing out of the trigger/sear interface and an internal lube of mainspring and piston.
Shoots like a dream now.

Pete.

[clarky]

Matt,
I had the same problem. I re-profiled the grips at the top using a dremel drill ,where the knuckles of your thumb and index finger of your shooting hand tend to rub into the grip.
I added weight to the inside of the grip by drilling two holes and filling them with melted down lead pellets.
then just a smoothing out of the trigger/sear interface and an internal lube of mainspring and piston.
Shoots like a dream now.

Pete.

I ran all the tests and performed major tunes across a 12 month period after it first came out. I also purchased it due to its its less bulky appearance compared to the 45 i had but my conclusions realised it was not as good by some margin.
The main problem is the novel guide rod. The idea was to use a cross corners guide in the shape of an X in section, instead of round. Made from Black Nylon. It has a very tight fight, the idea being to grip the unwound mainspring, removing any twang at the end of the cyle.
While it did seem to work as a spring damper, it is tragic at returning top performance. There is not enough slip for the spring at these lower power levels. Also the nylon is not perfect, with high spots and the moulding is not perfectly straight ...as i found out when i ran it in a lathe.
I produced a replacement Blach Delrin guide but of round section. Front section was exactly similar to fit as forend plug of course.
I got a good improvement with no noticeable increase in twang.
However there are other problems. The breech washer never worked efficiently and even came out. There didnt appear much that i could do about it. Many reported similar problems but also struggled to come up with a fix.
Finally the barrel is too short. I wish BSA had not gone with the so called Plenum chamber in attempt to act as a small integral silencer. It may have had some slight effect but robbed a potential 2 inches of barrel length. Cardew did some tests many years ago where he concluded that a minimum of 7 inches would be required for the sub 6ftlb gun to perform to any reasonable accuracy. Suppose the Webley pistols just about made it at 6.75 inches but the Hw45 7.75 is a notable.

[Rob M]

I really like these pistols and prefer them to HW45s, one of my favourite pistols in fact, along with Tempests and Hy-Scores. I own two 240 Magnums and I've never had trouble with the breech seal popping out. I've messed around a little with one of them, I fitted a shortened Record Jumbo spring lubricated with some Moly gun grease and GN paste into mine, in an effort to see if reducing the power made it sweeter and easier to shoot, and was really pleased with the result. It's much easier to cock, sweeter and easier to shoot accurately, I'm really happy with it. I was expecting the power to drop to around 2.5 ft/lbs or maybe even less, but on the chrono it turned out to be shooting at over 3.5 ft/lbs. I was surprised, it felt like less. Like I say though, much sweeter and easier to shoot, and cock, much better for short and medium range plinking which is what I tend to use my pistols for.

[clarky]

I really like these pistols and prefer them to HW45s, one of my favourite pistols in fact, along with Tempests and Hy-Scores. I own two 240 Magnums and I've never had trouble with the breech seal popping out. I've messed around a little with one of them, I fitted a shortened Record Jumbo spring lubricated with some Moly gun grease and GN paste into mine, in an effort to see if reducing the power made it sweeter and easier to shoot, and was really pleased with the result. It's much easier to cock, sweeter and easier to shoot accurately, I'm really happy with it. I was expecting the power to drop to around 2.5 ft/lbs or maybe even less, but on the chrono it turned out to be shooting at over 3.5 ft/lbs. I was surprised, it felt like less. Like I say though, much sweeter and easier to shoot, and cock, much better for short and medium range plinking which is what I tend to use my pistols for.

Its quite possible that by coincidence you negated the effects of the very tight fit of the mainspring when swapping out the spring for one of lower power.
Thus, the low power you were expecting from the weaker spring was at least returning all its energy and quite probably why you didnt see the big predicted loss of velocity.
Lots did have probs with the breech washer, with even the Tester on Test encountering a problem. Think this is a bit hit and mess, where you either get a good one or a bad one
However, with a 45 hitting the sweet spot (cleaned out of all grease and a Nylon guide) i have happily trounced the Magnum on all levels apart from its bulk.

I recently tested the new Tempest though after reading the recent review. Its doing a full 1ftlb more power due to a different seal arrangement. Amazing consistancy too.
I also kinda liked the new matt finish above the gloss finish of the English version but some might not. Powerful gun though.

[Nikkormat]

Thanks for the replies gentlemen. Some interesting findings there, Clarky. I desperately wanted to like the 240 Magnum but just couldn't because I couldn't get any accuracy out of it; I know others can (with perseverance) but I sold mine after a couple of years. I suppose the answer is a HW45, but I can't get on with its looks.