Questions to BSA Improved Model D owners

[edbear2]

Hi Ed,

Thanks for the reply, that's quite interesting I had a sneaky feeling having had an Airsporter back in the 70's that it would be better with a lighter pellet and possibly a slightly bigger skirt. My old 0.22 Airsporter was way better with the 5.6mm Wasp pellets than the 5.5mm version. I think I'm right in saying older BSA barrels were slightly bigger than later ones / European ones.

Thank you for your kind offer of the pellets, I'll hold off for the time being, Mark who I bought the gun off gave me a quantity of RWS Superdomes (8.3gn) that he'd been using for Bell Target competitions, these seem ok, and I also tried my usual JSB's but the skirt must be smaller ( 4.52's ) as they drop straight in

I saw the ms025 spring on the Chambers site listed under the BSA section "Standard" funny thing is on the improved model D listing they quote a std spring pair, light version and a 0.22 version then a 0.25 one ! No mention at all of 0.177 ?
I think I saw somewhere that the model D in 0.177 is rarer is this right ( saw it quoted as only 1 in 10 made were 0.177 compared to 0.22 )
The very least I'll do is get a new piston seal for it.

Many thanks,

Norm

Hi Norm, the springs are as follows...BSA made essentially 3 sizes of Improved gun pre 1914 with the same cylinder dia, as well as a reduced dia gun called the Juvenile, they are to keep things simple determined by the compression chamber length, but it is easier (and the norm) to refer to the overall lengths of the guns which are (approx as stocks can vary) 45 inch, 43 inch and 39 1/2 (I think without reference at the mo').

So...the 45'' gun was in .22 or .25 only, the 43'' gun in .177 and .25 (both sizes of .25's are very rare!) and the shortest is the Light model.

Chambers should really list their springs by action length to be clear, and it would be worth an email to clarify which is correct, but I am 90% sure the spring pair will be correct for a 43'' gun, but you can also fit a single long spring, and in this case it is easier to shorten one rather than two if needed.

The dual, opposite wound springs were advertised to counteract torque on firing, and were standard in .177 guns, but a single spring was also used. I have shot both and the dual springs feel slightly ''softer'' on cocking, and when fitted to the longer .22 versions feel slightly different on shooting to me, but some folk say they cannot notice any difference.

Tons of info here about the various types, and hints and tips plus reference material;

http://www.network54.com/Index/105071

ATB, Ed

[Mr.Fixit-Norm]

Thanks for all the info & links, it's very interesting, I loved the link to the original manual !

I've taken mine apart tonight to get a better insight of its internals and make some measurements.

This is what I have so far ( sorry about the mixed units )

Overall length 43.5"

Single piston spring 215mm long x 20mm dia. 24.5 coils looks straight with even spacing between coils

Piston washer looks in good condition and doesn't look that old - no deterioration, the piston is a lovely tight but smooth fit in the cylinder and looks like it has moly grease on it

Stock is marked underneath 14 1/2 ( presumably inches ) for the stock length

Action underneath marked Pat No. 11817-05 with J J and what looks like 54 ?
Serial no. is 28026

Given the overall good condition of the piston washer but lack of oomph, I'm guessing I need to source a better spring or springs
I did email Chambers with the details of my gun ( caliber etc ) and asked which spring they recommend but they just refered me back to the Model D section of the site, not exactly helpful when they list 3 or 4 spring types !

Going by Ed's suggestion, I might go for the single ms025 spring used on the BSA "Standard" unless from the info I've given above anyone can recommend anything else?
Many thanks,

Norm

[Mr.Fixit-Norm]

Actually, just gone back to the Chambers website and it isn't the BSA Standard listed with the ms025 spring, I did find that one and it lists it as having 40 coils given mine has 24.5 I think that would need some serious chopping !!

They do a 30 coil one as well just a shame they don't list the overall number of coils for the ms017 'pair

I'm a bit torn now between the safe option of the ms017 pair listed under the Model D section or a longer single spring and cut it down to given the optimum power.

Norm

[edbear2]

Actually, just gone back to the Chambers website and it isn't the BSA Standard listed with the ms025 spring, I did find that one and it lists it as having 40 coils given mine has 24.5 I think that would need some serious chopping !!

They do a 30 coil one as well just a shame they don't list the overall number of coils for the ms017 'pair

I'm a bit torn now between the safe option of the ms017 pair listed under the Model D section or a longer single spring and cut it down to given the optimum power.

Norm

Hi Norm, read the bottom of this article;

http://www.network54.com/Forum/67044...nd+performance

And the last line here;

http://www.network54.com/Forum/67044...f+vintage+BSAs

And somewhere else is a improved 42'' I wrote about that I had aquired that was rusty on the outside, but like new inside, with the spring info. As I recall, (I have not been doing many of these lately), no-one makes an exact spring for the pre-war guns, the knibbs springs, although the correct number of coils, are more open wound and normally over-long, and the T.W. Chambers are the closest, but are a bit soft temper. I have the wire gauge and length info somewhere and was going to investigate getting a 100% correct 43'' double set replacement quoted, but have just not got around to it

I had a small stock of original springs, mostly for 45'' guns, but have tried all sorts and normally would play with an airsporter single spring in any 43'' gun I was doing, will have a look inside my 2 remaining 43'' guns at the weekend for you

ATB, Ed

[johnbaz]

Norm- If you prefer the two half length BSA mainsprings, Look for a seller called Tigersau on fleabay, It's Chris Hough, Unfortunately he's not a member on here (He's on both the other Airgun forums though)...

Anyhow, pretty sure he still has orignal BSA replacement springs for the early quarter stocked Beesas- He's a nice fella to deal with too



John

[Mr.Fixit-Norm]

I decided on Friday to bite the bullet and go for the double spring set on the Chambers site ( the ones they suggested ). They arrived this morning and I decided this afternoon to fit them ( I also ordered a spare piston seal even though the original looks really good )

So far all my efforts have been disappointing , the spring pair as they come were slightly too long and I had trouble cocking the gun due to the springs binding so I took the plunge and just cut one coil off each spring ( I figured that both springs needed to be of equal length )

Unfortunately the results were very disappointing, the original power was around 4.2 ftlbs, now it's around 4.9 - 5.0 ftlbs , going in the right direction but only a very slight increase for the money spent the gun is also harder to cock? I can't believe that cutting 2 coils off has had that much of an effect anyway.

I could change the piston washer but I'm not sure that's the answer. ( or is it ?? )

I might try and find an Airsporter spring ( presumably a 0.177 one is needed ) and see if that will work, as per Ed's suggestion.
If anyone has one 'lying around ' that they want to sell please let me know.

Norm

[edbear2]

Hi Norm,

Some easy things to try (problem in brackets);

Pull the tap out and look at the small end for a number, then look under the barrel...should be stamped there as well. (not original tap)

Then re-assemble with a light coating of grease and see if the power goes up substantially. (tap air leak)

Check washer is tight.

The piston with washer should be an easy sliding fit in the cylinder, not tight at all.(too much friction)

And also use an engineer's straight edge to carefully check for ''bulging'' in the compression area.(dieseling causing bad seal due to enlarged bore).

Look very closely at the joint between the cylinder and loading tap area, the cylinders are screwed on, and then soldered, but can fail over time, hold the barrel / cocking arm area, and with the stock / back block off, try and unscrew the the cylinder (normal direction)...The slightest movement will be a drastic lack of power...This will entail cylinder removal and re-fitting with loctite, and easy job, will advise if yours needs it.

How much preload were the news springs by the way? (not actual including block, but how much was sticking out of the back?

ATB, Ed