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View Full Version : i have 2 9mm AR build questions!


pacrimguru
12-01-2009, 8:50 AM
i used to have a full spike's 9mm build and loved it. but i sold it and have regretted it ever since. so, i'm looking to build another 9mm, but this time i'm piecing it together myself in order to try to save some cash. i have 2 questions.

1) what happens if you use a .223/5.56 upper instead of a 9mm upper? i understand the real difference is that the .223/5.56 upper doesn't have the 9mm shell deflector. does this matter at all?

2) i'm contemplating on getting either a cmmg dedicated lower or a RRA block. i used to run a hahn block and man, those are nice but pricey. how do those RRA blocks perform? do they feed and lock back reliably?

thanks for anyone's input.

Dirtbiker
12-01-2009, 8:53 AM
Dedicated 9mm uppers do not have a forward assist or a bolt cam groove machined in. You can use a 223 upper for a 9mm build but not the other way around.

Hahn mag blocks aren't that much more than the RRA block and are much better. What's $40 on a $1200 rifle?

pacrimguru
12-01-2009, 9:05 AM
cool, thanks for the info.

yea, a RRA block is $150, a hahn block is $200, and a dedicated cmmg lower is $220... that's how my budgets get blown. i'm always saying to myself, well, it's just another $40... ahhhh!

anyone else have experience with the RRA block?

dizzy
12-01-2009, 9:09 AM
the RRA block works really well (once you have it adjusted for your lower). The only problem I had was getting it to work with CProducts 9mm magazines. I had to file the mag lip edges a bit so they did not drag on the bolt.

FYI, Spike's Tactical magwell block is on sale for $134.95
http://www.spikestactical.com/z/index.php?main_page=product_info&cPath=68_71&products_id=188

I just ordered it for a second 9mm lower I'm putting together.

tiger222
12-01-2009, 9:09 AM
I had an RRA that I never shot, and the adaptor would move slightly even when tightened down. Maybe that isn't an issue. I now run a Hahn dedicated and it hasn't let me down in any way. Wish it was slightly less, and I'm sure the RRA's are just fine, but.......

NavDoc
12-01-2009, 9:26 AM
I highly recommend the Hahn dedicated block. Why would you want to "adjust" a mag block? Wouldn't you rather "Set it, and forget it"? :D
Mine has been perfect with C-products mags. If you wanna go cheap, however, I completely understand. Thus, you may want to take a look at Spikes Tactical new 9mm block. It looks like a quality piece, and at $135 it is cheaper than the RRA block.
Go here...
http://www.spikestactical.com/z/index.php?main_page=product_info&cPath=68_71&products_id=188

Good luck!

pacrimguru
12-01-2009, 9:27 AM
the RRA block works really well (once you have it adjusted for your lower). The only problem I had was getting it to work with CProducts 9mm magazines. I had to file the mag lip edges a bit so they did not drag on the bolt.

FYI, Spike's Tactical magwell block is on sale for $134.95
http://www.spikestactical.com/z/index.php?main_page=product_info&cPath=68_71&products_id=188

I just ordered it for a second 9mm lower I'm putting together.

thanks for the heads up. i might just try the spikes block.

pacrimguru
12-01-2009, 9:28 AM
I highly recommend the Hahn dedicated block. Why would you want to "adjust" a mag block? Wouldn't you rather "Set it, and forget it"? :D
Mine has been perfect with C-products mags. If you wanna go cheap, however, I completely understand. Thus, you may want to take a look at Spikes Tactical new 9mm block. It looks like a quality piece, and at $135 it is cheaper than the RRA block.
Go here...
http://www.spikestactical.com/z/index.php?main_page=product_info&cPath=68_71&products_id=188

Good luck!

again, thanks for the heads up on the spikes. i might just be our calguns guinea pig for this one.

esskay
12-01-2009, 10:43 AM
again, thanks for the heads up on the spikes. i might just be our calguns guinea pig for this one.

Hey dude, got a Spikes block, you can check it out.