which spring is related to 21-105

I am looking to purchase your 21-105. However all the springs you offer online are either too big or too small the 2 closest ones I was able to see is products 21-151 and 21-156. If you could please offer some insight on which springs would fit best with this pin cap, that would greatly be appreciated.

Thank you in advance for your time.

I have not seen any response to this question yet. Is someone working on it?

Is it possible for me to cut down the 21-126 to reduce the bottom OD to fit onto the 21-105 end cap, or will that reduce the necessary vertical tension?

Thank you.
---lar

No,

I thought of that but I do not believe 21-251 barrel spring will fit over the throat of the 21-105 nylon cap.