Same BCG for 5.45X39 and 5.56?

[mmeece]

I realize this is a very basic question, but I'm inexperienced in this area. I have an AR in 5.45X39. If I change the upper to 5.56 do I need a new BCG?

 

[Sam7sf]

Sixteen thou difference or eight per side. I don’t know i never tried to see what kind of malfunction it could cause. Probably a lot. Lol.

At one point I was looking at building one.

 

[Sam7sf]

I’m going to give a request to @zackmars for possibly more info and possibly @Maverick44

 

[zackmars]

Yes, you will need a new bolt at the minimum. I would just go ahead and either piece together another BCG or buy one complete just for the convenience factor

 

[mmeece]

Yes, you will need a new bolt at the minimum. I would just go ahead and either piece together another BCG or buy one complete just for the convenience factor

Thanks!

 

[Sam7sf]

Yes, you will need a new bolt at the minimum. I would just go ahead and either piece together another BCG or buy one complete just for the convenience factor

I never messed with one. Was there actually a difference in carriers?

 

[zackmars]

I never messed with one. Was there actually a difference in carriers?

Carriers, no. Really only the bolt should be any different, MAYBE the firing pin. Its just a PITA to strip the bolt when swapping uppers.

Plus keeping the BCG with the specific upper prevents any confusion

 

[Sam7sf]

Carriers, no. Really only the bolt should be any different, MAYBE the firing pin. Its just a PITA to strip the bolt when swapping uppers.

Plus keeping the BCG with the specific upper prevents any confusion

True I forgot commie ammo typically needs more firing pin protrusion.

Im losing my mind. Being I developed a couple uppers with a now defunct company you would think I’d remember that. But one could just turn down the fillet on his pin. They hold up to 7.62x39 that way.