Posted: 7/21/2007 7:52:23 PM EDT
| Is the 9mm upper just a 5.56 with some sort of clip on deflector and a short door? |
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RRA uppers do not come with a hole drilled for a gas tube. I assume if the hole was there some gas would escape out of it and make for a nasty gas discharge out the front of the upper receiver. You can use a DPMS hammer just fine as well. I have also heard the timney trigger works fine too. |
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My RRA 9mm did not work at all with an AR/M16 type hammer. It totally jammed the bolt half open. Do you know how hard it is to resolve a bolt jammed half open...? If you are going RRA, you must get the rounded off 9mm hammer. However, the 9mm hammer should work fine in your AR15, as will the heavier buffer. No gas tube b/c no direct impingement. It’s a blowback carbine |
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Not really the upper, but the bolt is also different. The bolt and carrier are one piece. and I could be wrong, but the 9mm bolt is also lacking a full gas key. If you do decide to go the 9mm route, I would send your bolt to M60joe to have it ramped. It definitely improves function. |
Unless you are building an NFA (full auto) complaint carbine, don't mess with ramping, According to his website M60Joe won't even do semi-auto bolts. KNS pins are a good call though. KNS pins at Brownells |
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Pretty much all 9mm bolts are full auto style bolts. Of course that is not to say that if you are using a full auto bolt, you will have a full auto rifle. The semi versions are fairly rare as they were only produced for a short time. I don't know of any manufacturer currently producing the semi bolts. The ramping also has nothing to do with semi or full auto fire. You get the bolt ramped to reproduce the standard geometry of the 5.56 bolt carrier engagement surface, and can therefore use standard 5.56 hammers. The gun using the parts that they were more or less, designed to use, you will find, are more reliable. |
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hooled! I thought ramping was only for rate of fire issues with full auto fire and to reduce the impact on the hammer/hammer pins. Now I know. |