Re: My first AR build
Your question would probably be better in its' own topic, but I'll try to answer anyway.
I have a bunch of 9mm carbines, but not an AR carbine. I'll tell you that up front, but I do have experience with them.
As for the "special" hammer, that isn't a big deal. You can use it in your regular AR lower too. or you may already have the hammer.
The preferred hammer for a 9mm upper has a flat face, with no high ridges that can catch/bind the bolt. Most guys I know use DPMS hammers for their pistol cal builds. So that's not really anything big to worry about.
I'm fairly certain that there are only 2 styles of 9mm upper available. The colt/RRA/CMMG style, and the olympic arms style.
Most people will usually say the colt style needs the bolt ramped and polished. And the olympic style is ready to go onto a regular lower and fire control, but needs to buy their modified sten magazines, or a Hahn mag block and use regular sten mags
Here's a couple of links to help you out.
http://hahn-precision.com/Sten-9mm-Adap ... ST0105.htm
http://olyarms.com/index.php?page=shop. ... t&Itemid=5
http://oa2.org/Forum/viewtopic.php?f=65&t=6493
(PS if you call and order it from the factory and want a flat top, you can order it without the carry handle and save some cash over what's listed on their website).
Also, they have only recently began making their proprietary magazine that doesn't require a mag block and fits in a regular AR magwell. The magazine has all the extra mumbo jumbo made into it). You get one with the upper, but extra's are far too expensive in my humble opinion. But they do make it a lot more plug and play and one normally comes with the upper if you order it from them anyway.
If it were me going that route, I would buy the flat top upper without carrying handle, and the Hahn precision olympic style mag block I linked above and a ton of surplus sten mags. Just my 2 cents.
If you plan to use a collapsible stock, you will also need a 9mm buffer (which are heavier than a normal buffer) on any style you choose to prevent it from battering the bolt carrier too bad when you shoot. That's required no matter which type of 9mm upper you want and is just the nature of the beast because pistol cal uppers are direct blowback and don't need a gas tube or gas block, etc. So a heavier than normal buffer is going to be needed either way.
Doesn't have to be from here or this brand, but here's a link to one to show you what I'm talking about.
http://www.rainierarms.com/?page=shop/d ... duct_id=85
If you are using it with a regular rifle A1 or A2 buttstock, no special buffer will be needed because rifle buffers are inherently heavier and made different than a collapsible stock buffer.
If it were me going that route, I would buy the flat top upper without carrying handle, and the Hahn precision olympic styl mag block like I linked above and a ton of surplus sten mags. Just my 2 cents.
