The dimensions I find online are for extra power springs.
IF I was able to identify the correct springs, a stock 2240 hammer spring gives about 450fps with RWS 14,5grs superpoints.
The cut down spring in the gun has a bit thicker wire, is shorter, and gives abiut 420fps with the same pellets, and is more comfortable to shoot in the basement.
I just ordered springs from that bay-place, 10 each of 0,8 x 7 x 50mm and 0,9 x 7 x 50mm.
That will give me room for some cutting