Hi, PJ:
More about the mag tube spring:
A engineer friend that has a lifetime of making ultra-high spec. COIL springs used in weapons and atomic submarine systems from small to huge shared that it is NOT the static compression that weakens them so much as the CYCLING between uncompressed and compressed, presuming decent metal and temper. Tempering IS the troublesome aspect. It ALWAYS varies, so springs of the same rested length can have different strengths. A good coil spring can sit fully compressed for YEARS with no significant weakening.
When we made guns, yep, we designed them to use SECTIONS of either GI ISSUE M1 Garand op rod or 1911 recoil springs because WW II springs were always available and were the BEST quality. These days, I would ADD Wolf Springs. Many gun makers RELY on Wolf springs, esp for box magazines, where lives are at risk.
As I shared, I have several with the same alloy and wire OD, BUT of VARYING OAL's that feed first and last rounds just fine and can be swapped between mag tubes AND STILL function fine. I suspect that it is a temper thing. It IS BECAUSE of temper and length variations, that I got several and fussed with them.
I suggest NOT cutting it yet. There are Threads about this topic, BUT I suspect some involved more than one issue instead of only the mag spring tension. You have feeding resolved, so .....
Instead see if it will "break-in" a little over 50 to 100 cyclings by putting 7 in the butt and running the tube in and out. Probably won't do much, but better to know. If it improves, look out because a good one should NOT weaken in such a short interval. If no better, and that's preferred, see how much of a tube protrusion does help with FIRST and second round feeding. That will confirm if the spring length should be shortened. BUT, shortening to get the first couple to feed may THEN cause the LAST one not to feed. Get first two corrected and you can always put a shim under the butt end of the spring to fine tune length.
Bet a better trigger pull will improve those already nice results.
Kevin