Universal carbines were indeed mil spec. as they were assembled from USGI
surplus parts till the late 1970's. When the supply of surplus mil spec parts
dried up and they had to design their own operating slide. There were failures
due to the operating slide's weight,thickness of metal used,shape,and location
of welds. This also caused the recoil spring guide and springs to fail.
After a year or so and several redesigns they got it right but the damage had
been done. The reputation of Universal carbines and sales had hit rock bottom.
The company was sold to Iver Johnson in 1983.

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