Clearly too late for you, but maybe others will come accross this thread.

I found an easy way to clean the remains of the sprue off of the horns by leaving them partially attached. If you take off the bits in-between each horn only, there's just enough room between them to insert a sanding stick.

I found cleaning them while holding them between fingers (and I do not have sausage fingers) was a bit fiddly. This is much easier.

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For the life of me I did not expect to see US armor cast in panzer-yellow plastic though.