Brownells only lists one spring.
ACTION SPRING - Brownells
They call it a "common part" #@$%!
I've considered shortening it a little at a time until I get 100% function.
It seems my only choice.
After thought on this, I'm presuming you've got new gas o-rings in it and have checked to make sure the pressure rings slide freely... ... considering you drilled the gas ports out, I'm presuming.....
So that leaves you with either making your own, lower-compression spring, or shortening the one you have..... They're not too bad. I'd go 1/2" at a time, IMO. Good luck.
The guns that were only made for two years had a different piece that fit into the receiver. It was short, like an 870 Barrel. The model number of those escapes me at the moment.
Yep. You said that so I had to go look it up... . It was the Sportsman 12 Auto, a variant of the 1100, made 1985-86. Not valued at very much, but a good shooter.
Anyway, it seems you have an early, 1964-69, 1100 20ga Standard Field. They were only manufactured in the magnum chamber in the 20ga under the "Standard" label with the 12ga reciever those years, and then they went to the Lightweight or Mag 20 designation, with the exception of the Skeet A & B grades. I didn't find a number on the amount produced..... that might require a call to Remington... . They went to the LW-20 reciever in 1970, with 2 3/4" chamber. It appears the 1100 Magnum Duck Gun, 1963-88, was the option for those wanting a 20ga magnum chambering after 1969, until 1977 when the LT-20 MAG was introduced..... according to my books, anyway.
A call to Remington might reveal alternative routes for parts, as well. Good luck!