Quote:
Originally Posted by Electronic M
I doubt it had a trap from new but some of the early aluminized types did either due to logistics or cases where the standard type of a tube was non-aluminized but the A postfix version was aluminized.
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Indeed, it appears that the first configuration of the tube was not aluminized, only the A and B were. The later versions provided a brighter picture, but the gun design was not changed.
https://frank.pocnet.net/sheets/127/2/21AUP4.pdf
jr