Short cylinders/long barrel shank means that the bullet has a shorter path from the cylinder into the barrel.

If you can find a picture of a M25-3, which is the 125th Anniversary Model chambered in .45 Colt, the cylinder is short. When the M25-5, chambered in .45 Colt, was introduced, S&W used a longer cylinder.

"...maybe this did not happen with earlier S&W factory chambered .45lc examples?"

There were very few S&W revolvers built in .45 Colt. Most were special order until the M25-5 was introduced in 1978.

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