Yes, but many of the earlier generations the buffer tube was not mil-spec and wouldn't accept a mil spec stock. That was only a guess though.
This is where my theory is debunked.
Perhaps it is the LoP that's the issue with SBA3 ( ? ) which is more of a question than an answer.
It's hard to keep up with all of this.
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So you can’t have it on an A5 tube???