Quote Originally Posted by Phil Russell View Post
So as to avoid any confusion, can you confirm that the above spring measurements are for the Tx MK2? I will then add them to the database.

The current database entry reads:
Air Arms TX200 Mk1/2 21 (20.75)od 3.25 wire diam 207 / 220 length 23 active coils Source from Forum so very close to your posting.

Cheers, Phil

PS what is mean diameter? I can see it is id plus wire but I have not seen it quoted before.
Yes that was for an OEM Air Arms mk2 TX200 spring with the collapsed coils. Purchased some time last year.
The length I measured was 'active length' so it doesn't include the collapsed coils at the end. They would add about 10mm I guess to the total length. Next time it's apart I can check.

Mean diameter is the diameter at the axis of the wire if that makes sense. i.e half way between outer dia and inner dia. That's the number needed to calculate the spring constant (k).

I have a spreadsheet that calculates efficiency of my competition TX200. I know it should be between about 36-40% when it's all working well. If it drops much below that I know there is something wrong. So I know to check the seals and spring etc. Sometimes this gun gets stripped and rebuilt twice a week (if it's a wet weekend with 2 shoots on) so it's worth doing. However the TX is mega and has only come up short twice in about 18 months.


Make Air Arms
Model TX200
Date 22/4/19
Active coils 23
Length 200
Coil OD mm 20.7
Coil dia mm 3.24
Mean dia mm 17.46
Coil ID 14.22
Stroke 83
Preload 12
k 8.923

Pellet speed fps 770
Weight grain 8.44
Power ft-lb 11.11
Joules 15.07

Spring Rate fitted N 107
Spring rate cocked N 848
Average rate N 477
Recoverable energy Joules 40

Efficiency % 38.0