Queen question

[treefarmer]

I saw a Queen #27 Barlow, it does not have a tang stamp but has a patent number on the mark side of the main blade(sheep foot) where normally a stamp is located. It has the etch on the same bade "Queen Steel #27".
Any idea what era that knife would be from?
Treefarmer
edit: the patent # 2728139 is for the "Big Chief" knife construction made by Queen dated 1953.
Okay, digging a little deeper this #27 is one of the closed spring Barlow's made by Queen.
Should have dug a bit deeper before I asked the Question.
Treefarmer

[TwoFlowersLuggage]

Well, from the patent you know it is post-1955, and there was no tang stamp, etch only from 1961-1971, so that seems to fit.

[treefarmer]

TFL, seems like there were no blade markings other than the etch on Queen pocket knives during the '61-'71 era. The reason we are told was the lack of tang stamps was a cost cutting measure. My question then would be, why stamp a patent number on that particular knife during that era?
Maybe someone has another Queen with this marking. The pattern #27 was also apparently used on the regular Barlow style knives, the ones with brass liners and regular frames. The patent number most likely only applies to those knives with the hidden springs and aluminium frames .
Queen seems to have changed a lot of pattern numbers over the years in order to make Queen collecting more interesting!
Treefarmer

[TwoFlowersLuggage]

Well, I'm just speculating, but one difference between stamping the model number and stamping a patent number is that you can have the same patent number on any knife model with that type of blade and that type of spring. They don't have to change the stamping machine for each model of knife.

My other thought is that perhaps they stamped a bunch of blades with the patent number after the patent was granted in 1955, because they wanted to make sure they had rock solid evidence that they were asserting the patent. They could have been using blades that had been stamped a couple of years prior to the 1961 decision.

But, I gave-up a long time ago trying to figure out why knife companies do the things they do...