So, I have a new AR, a Bushy carbine... happy happy joy joy! But... I also want a 9mm upper. I though about 45, but I already use 9mm for my pistol, so I don't need to buy another type of ammo, and this way it's cheaper anyway. I'm thinking buying an RRA upper... but what else do I need? Do I need to replace my hammer? If so, will the new hammer work with my 5.56 upper? Can I use Sten mags? What mag block? Release doesn't matter, in fact a paddle might be preferable. Should I replace my buffer? It's a collapsible stock, if that matters. With an A2 from ADCO at 400, how much am I looking at spending?

Don't say look it up, please, I already tried searching, but I'm stupid and can't really find anything.

Quoted: So, I have a new AR, a Bushy carbine... happy happy joy joy! But... I also want a 9mm upper. I though about 45, but I already use 9mm for my pistol, so I don't need to buy another type of ammo, and this way it's cheaper anyway. I'm thinking buying an RRA upper... but what else do I need? Do I need to replace my hammer? YesIf so, will the new hammer work with my 5.56 upper?Maybe, but if you get a 9mm hammer and an extra spring for it, you can swap them out by just removing and replacing the pin. Can I use Sten mags?With the Olympic system but not the RRA What mag block?Read the FAQ Release doesn't matter, in fact a paddle might be preferable. Should I replace my buffer?Maybe, but to be safe, yes It's a collapsible stock, if that matters. With an A2 from ADCO at 400, how much am I looking at spending?$450 should cover the upper, hammer, spring, and buffer. Up to $150 on a mag block and $10 to $25 on each mag Don't say look it up, please, I already tried searching, but I'm stupid and can't really find anything.

There you go, you lazy bastard! (just kidding on the lazy bastard part)

Just go with an OLYMPIC ARMS so you dont have to change anything in your lower and get a KKF magblock and then you can use $4.00 sten mags

You don't have to replace the hammer if you have the 9mm bolt ramped.  Joe Black can do this for you.

It is possible to use sten mags with the RRA upper.  However,  you have to modify a two piece mag block and notch the sten mag.  A few of us here including myself have done this conversion.  You can check one of the threads for more info.

I used a ASA set up one peace block that is held in by both mag release and upper receiver. No last round hold open on the ASA block. I use both 25 and 32 round uzi mags. I like the mag block over others that fall out when you do mag changes.  Sten mags are hard to load. You need the loading tool to make the gob easy. The Uzi mags load right up and dont trash your fingers when loading. With the ASA there is no need to change the hammer. Have the bolt ramped it saves on lower pins. I went with a H-bufffer. My gun runs eto slow with a subgun buffer. I bought my 1st
set up for round 500.00. Watch the equipment exchange you my be able to the items you are looking for there


hope this helps