Blocking bar in receiver questions

[Dakotastomm]

While we're all here. I have a question regarding blocking bars.


I noticed several of the receiver shells floating around don't have them installed. Ie, the century arms shells, some of the group industry shells, vector etc.

While the mckay shells come with one pre installed. At what point are they required? Or when does atf deem a shell without a blocking bar a mg?

 

[arch stanton]

Yes unless you are making a post sample machine gun. Your semi auto will need the blocking bar to prevent FA bolts from being used. All semi auto bolts are slotted.

 

[cajun 22]

When you weld in enough parts to make it run.

 

[Dakotastomm]

Im aware that

Yes unless you are making a post sample machine gun. Your semi auto will need the blocking bar to prevent FA bolts from being used. All semi auto bolts are slotted.

I'm aware that they need to be in fir semi builds. I guess I was more curious as to why some shells come with them ore installed vs not

 

[arch stanton]

They come with or without based on how much work you want to do and your budget. Some guys like to do the complete build others like some of it done for a partial build.

 

[slimshady]

I would imagine it is also a CYA move. "Hey, when I made it and sold it the blocking bar was welded in there, the customer must have knocked it out to make his illegal MG. Talk to him, not me!" Other companies have less paranoid attys...