why so many toggles swapped in VOPOs?

[DonVoigt]

Originally Posted by Patrick Sweeney

The M1 carbine was another special case. When they were made, there was little thought to matching parts. The Carbine Committee would have excess production shipped to other arsenals for use in assembly. they were so serious about maximizing production, they even told Winchester to not bother making barrels, Inland could supply them with all they needed. Winchester being Winchester, they still made barrels, but grudgingly used Inland barrels to meet production quotas.

Several wars later, and with multiple rebuilds, if a carbine is "all matching Winchester", it is likely because a collector scoured gun shows until he had all the parts needed, and assembled it himself.

I'm not sure where you got your "information", but it is not accurate with regard to Winchester and barrels.
Winchester made all barrels for its own production of over 800k carbines; and barrels from Winchester would have been made available to others via the "Barrel Free Issue" mechanism.

Winchester did acquire some receivers from other subcontractors.
These are marked on the bevel to show their origin.

Original Winchester carbines would be and are often found as made by Winchester- "matching Winchesters" are not any more likely to "assembled" by a collector than any other carbine.

Winchester received no documented barrels from Inland.