I believe the Springfield musket was the standard weapon for the Federal troops. Only about 15,000 Spencer's or Henry's were distributed to them making them highly prized.
The presenter had a chart listing about 2 dozen makes of repeating rifles used by the Union during the civil war, each with unique ammunition. Henry’s and Spencer’s were indeed highly prized. The South could manufacture neither repeaters or ammunition for them. When they captured a Union repeater, it was worthless, except as a club.
The Springfield rifled musket was also standard in the south, as many had been stolen by the rebels. At Vicksburg, Grant permitted his soldiers, mostly armed with Enfield rifles, to exchange their rifles for captured Springfield rifles turned in by the paroled confederate soldiers. So many did so that bean counters in the north reported the failure of the blockade, as captured rifles from Vicksburg were mostly Enfields which somehow made it past the blockade.
The fog of war, coupled with the stupidity of bureaucracy is an enduring constraint on humanity.
So many Springfield rifles had been stolen by the rebels, that there was a shortage in the north. Enfield rifles were purchased and used. They were exchanged for the superior Springfield when an opportunity (capture or new production) presented itself.