This may sound like a dumb question, but i was curios if i put a 7.62 upper on my bushmaster a2 lower reciever would the hammer be able to sustain adn not wear down over time from shooting the higher caliber and heavier bullet?..its a 5.56 lower reciever?

i know its dumb b/c i put my .223 upper on my friends 7.62 lower and it worked, but i did not want to shoot a 7.62 bullet w/ my reciever until i knew for sure it would not harm my hammer?

so if anyone has ever done this themselves,, please let me know?
I have already heard that it should be interchangable, we even put his upper on and dry fired it?...but i dont want to use the 7.62 upper unless iknow someone else has done it as well?

Harm your hammer?  Surely you jest. Without going into issues like gas port size and a whole bunch of other stuff, let me assure you that you can put a 7.62 upper on your .223 lower without fear.  The ONLY parts different on a 7.62x39 AR and a .223 AR are the bolt head, the extractor, and the barrel. Everything else is exactly the same.

thanks fo rthe answer, i figured as much but wanted reliable confirmation.

Now for the better question: WHY?

You can get get an AK variant for the price of the silly upper. then you have that poor lonely .223/5.56 Upper going "Put my pants on back on, dickhead... GET ME A LOWER!!!"  Unattended AR parts have a nasty habit of becoming full rifles.

Quoted: Now for the better question: WHY? You can get get an AK variant for the price of the silly upper. then you have that poor lonely .223/5.56 Upper going "Put my pants on back on, dickhead... GET ME A LOWER!!!"  Unattended AR parts have a nasty habit of becoming full rifles.

I fully agree that unattended uppers have a habit of begetting new lower assys.  On the other hand, the most accurate 7.62x39 rifle i've ever owned was an AR-----and I've got 6 different AKs and SKS's at my house.

thats my reason for wanting it....the accuracy of a AR 7.62 is far better than AK's....my buddy has the colt sporter, it blows any AK out of the water...making them look like complete shit...

and even if a new lower does come down the road, it will be down the road...for the money right now, i would want a reliable (yes i know AK's are reliable) adn accurate (not an ak) gun......requirements the AR seems to fill better..

not to say i dont like AK's either,,,they are some raw machinery i will own one,...one day

Quoted: then you have that poor lonely .223/5.56 Upper going "Put my pants on back on, dickhead... GET ME A LOWER!!!"  Unattended AR parts have a nasty habit of becoming full rifles.

That is so damn true..

I have a Colt 7.62x39 upper that I put on the M16 every so often.  As a matter of fact, I burned a couple of hundred rounds yesterday!  Once you get the mags functioning correctly it is a lot of fun.  I think the cycle rate on the upper is 900+ rpm.  After every burst, you realize that the rifle is pushing something fatter and heavier down its tube!

The thing about uppers getting lonely if they aren't in a loving relationship with a lower is very true.  The 7.62x39 upper is on a newly built LAR Grizzly lower when its not spending time with the 16!

Get it, enjoy it, and add one more to the collection!

Now let hope someone is making mags again for the upper...