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Posted: 6/26/2014 5:46:33 AM EDT
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My CMMG dedicated 9mm lower is on the way from Brownell's so the build has started. I have been looking at the guns in the photo thread and notice some use a standard upper with FA, brass deflector, and regular dust cover, while some use the modified dust cover with the large deflector for 9mm. Does it really make a difference? Is the 9mm deflector necessary for a right handed shooter?
I have a regular upper with FA available upper in the safe, or I can order one specifically for this build. I would really like the Aero Precision slick side but it doesn't look like it will be available for a while. Is a slick side upper an advantage? This will be a pistol and I already have a YHM 9mm suppressor, so I was thinking about a 5" to 5 1/2" barrel and a 7" to 9" rail. Is there a negative to such a short barrel with the blowback operation of the 9mm? What twist rate is optimal for 9mm? Is there an optimal barrel length, or just personal preference? Finally, I am planning on using a CMMG ramped bolt ($169 at Bud's). Am I correct in understanding that this is OK with a standard hammer like an ALG QMS or ACT? Thanks, looking forward to joining the 9mm club. |
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Quoted:
My CMMG dedicated 9mm lower is on the way from Brownell's so the build has started. I have been looking at the guns in the photo thread and notice some use a standard upper with FA, brass deflector, and regular dust cover, while some use the modified dust cover with the large deflector for 9mm. Does it really make a difference? Is the 9mm deflector necessary for a right handed shooter? I have a regular upper with FA available upper in the safe, or I can order one specifically for this build. I would really like the Aero Precision slick side but it doesn't look like it will be available for a while. Is a slick side upper an advantage? This will be a pistol and I already have a YHM 9mm suppressor, so I was thinking about a 5" to 5 1/2" barrel and a 7" to 9" rail. Is there a negative to such a short barrel with the blowback operation of the 9mm? What twist rate is optimal for 9mm? Is there an optimal barrel length, or just personal preference? Finally, I am planning on using a CMMG ramped bolt ($169 at Bud's). Am I correct in understanding that this is OK with a standard hammer like an ALG QMS or ACT? Thanks, looking forward to joining the 9mm club. With my 10.5" I don't run the deflector or a dust cover on my standard AR upper. I purchased the deflector but haven't found a reason to install it. I could be wrong, but I've read that the deflector is actually to deflect gas and not brass. Whatever the purpose for it I haven't found a reason to install it because I don't have a problem with gas nor brass to the face. 
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I have marks on my deflector also. I couldn't wait any longer for the Aero slickside either so I look a chance on this CMT slickside:
http://www.gunbroker.com/Auction/ViewUserFeedback.aspx?User=2507911 I seems like a quality piece. A standard upper will work but the slickside will be cleaner looking, it may be a lighter also. My CMMG bolt works with the ACT trigger. http://i1057.photobucket.com/albums/t381/tornado1861/DSCF0979_zps848265d7.jpg |
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I have a slick side upper on mine, have run at least 1500 rounds with no problems. I see no need for a deflector.
The hammer needs to be squared off on the corner. Most of mine have a notch at the corner and it would not reliably reset the trigger. I put in a standard DPMS hammer and now it runs perfect. I went with a Adco 5" barrel with 1:10 twist. I am very happy with it and seems to be the perfect length, plenty accurate for a 9mm You want a hammer like the one above You don't want this kind I have not decided on a rail. Thinking a 7" carbine rail would be good |
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Quoted:
I have a slick side upper on mine, have run at least 1500 rounds with no problems. I see no need for a deflector. The hammer needs to be squared off on the corner. Most of mine have a notch at the corner and it would not reliably reset the trigger. I put in a standard DPMS hammer and now it runs perfect. I went with a Adco 5" barrel with 1:10 twist. I am very happy with it and seems to be the perfect length, plenty accurate for a 9mmhttp://<a href=http://i1340.photobucket.com/albums/o734/PanhandleAR/dpms_hammer_zpscc5b0128.jpg</a>" /> You want a hammer like the one above http://<a href=http://i1340.photobucket.com/albums/o734/PanhandleAR/hammerwithnotch_zps2c18ade5.jpg</a>" /> You don't want this kind http://<a href=http://i1340.photobucket.com/albums/o734/PanhandleAR/9mm011_zpsd957d4b0.jpg</a>" /> I have not decided on a rail. Thinking a 7" carbine rail would be good The 9mm is sweet! The planter is a little freaky. OP, standard uppers w/ fa work just fine. If you have a ramped bolt a standard hammer works fine. Mine makes a neat pile at 4 o'clock with no deflector so im saying try it first. no input on the short bbl as mine is a 16" carbine. |
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I'm running a Sun Devil slick side upper on mine, I haven't installed the 9mm deflector yet, but I'm going to since I'm a lefty. I have a 4.5" barrel from Adco and 9" rail. http://pic20.picturetrail.com/VOL1424/13602099/24383929/409634832.jpg That looks like the barrel set up I want. Adco will thread the 4.5" barrel to 1/2 X 28 which will work with my suppressor. It seems like most 9mm barrels are threaded 1/2 X 36. |
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That looks like the barrel set up I want. Adco will thread the 4.5" barrel to 1/2 X 28 which will work with my suppressor. It seems like most 9mm barrels are threaded 1/2 X 36. Quoted:
Quoted:
I'm running a Sun Devil slick side upper on mine, I haven't installed the 9mm deflector yet, but I'm going to since I'm a lefty. I have a 4.5" barrel from Adco and 9" rail. http://pic20.picturetrail.com/VOL1424/13602099/24383929/409634832.jpg That looks like the barrel set up I want. Adco will thread the 4.5" barrel to 1/2 X 28 which will work with my suppressor. It seems like most 9mm barrels are threaded 1/2 X 36. Ya mine is threaded in 1/2 x28 so it can easily mount my Octane 45 |
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