Those are fine rifles . My Dad bought me a BDL version on my 12th birthday in 1976 and I still have it.
I'll share my experiences with that rifle...
- As you requested, I measured my original mag tube spring... 26-1/2" free length.
- After tens of thousands of rounds, mine started misfeeding so often that it just wasn't fun to shoot anymore. I fiddled with it a few times over the years trying to fix it. I cleaned and cleaned again. I replaced the magazine tube assembly. I replaced the extractor. Nothing seemed to help and I was about to give up when I noticed that the bottom of the bolt, where it rides across the hammer, had noticeable wear on it. I think it had raised a burr/step that was slowing the bolt down. I smoothed that out and it ran like a champ again.
- A couple years later, it started misfeeding again, but this time it was only with high velocity ammo. Standard velocity ammo worked fine. I pondered that for a while and thought perhaps the bolt might be bouncing back too hard. I replaced the recoil spring and the buffer and that seems to have fixed it. My guess is that the spring had gotten weak and/or the rubber buffer had hardened with age.
These days, it's still running great and dotting i's as usual.
Hope some of this helps. Good luck on your project.
