Bama, I suspect the same with the S&B steel case ammo. It does surprise me though as S&B brass case ammo usually runs warm. Anyway, I cleaned the rifles yesterday and paid attention to the internals while doing it. There is not much wear and I have put maybe 60 rounds through each myself, so not much. Springs were in excellent condition but I do worry about heavy wear on the other parts do to over gassing.
When you replaced the spring on yours did you get the gas adjustment you were hoping for? If replacing the springs with yours is preventative maintenance then I would like to get a couple and replace them now before excessive wear or damage. Thoughts?
1. Set your gas to "3" for the S&B Steel cased ammo and test for function, set it lower by 1 click if it fails to operate reliably and repeating until it does run reliably.
2. The original springs' interior surface fully-contacts the OpRod and any carbon fouling of the OpRod will act like sand paper on the spring - eventually it will flatten the inside of the springs' surface thus reducing coil diameter which will weaken the spring and provide less recoil control and then as a result of this spring-wear will start to beat the bolt/carrier to death. Keep the spring & OpRod clean.
3. I never got the rifle to fail using my ammo even using the new springs that I designed on a gas setting of 5 - this indicates [to me] that my ammo is hot (in spec) and that the gas system adjustment design of the rifle could be in question, maybe not. (My bolt broke in 1/2 after around 9K rounds of in-spec brass ammo) so the system as designed and delivered is over-gassed, IMO which places violent forces that cannot be regulated upon the bolt/carriers action/components. The new spring is NOT a cure for this, it is just one small step in the right direction, IMO.
4. These new springs do not grab the OpRod and have some clearance so they will not wear out nearly as quickly as the original ones do. I will leave it up to you to decide if you want any of these new ones from me. I make no other claim than that they will be less prone to abrasive wear.
Best wishes and Merry Christmas, Sir.
/O
Steve.