Dead foot arms makes the shortest. It also uses a modified bolt. The only other really short one I've seen is on Bushmaster AR pistols, it's like 3 1/2 to 4 inches.I have been looking for shorter pistol tubes. I have the Strike Industries 5.5 inch, but haven't had any luck finding anything else that is smooth and reasonably priced. I question the SI tube because it has small indetentions for brace set screws.
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