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Posted: 9/24/2013 5:28:06 PM EDT
Well I just machined an "EP Lower" 80% polymer lower receiver, and I'm sitting here looking at it and wondering: How would this thing hold up in a 9mm application?

Has anyone done this?
Link Posted: 9/24/2013 5:44:45 PM EDT
When I had a 9mm upper I ran it on one of my CavArms lowers. Worked fine.
Link Posted: 9/24/2013 6:03:26 PM EDT
Thanks for the reply; that's encouraging. (I was worried about "egging" the hammer pin holes).

Can you estimate how many rounds you might have put through it?
Link Posted: 9/24/2013 6:20:46 PM EDT
Probably 5k rounds down my cavarms 9mm host, no problems.
Link Posted: 9/24/2013 6:25:57 PM EDT
I probably only had 500 rounds or so through it (I'm guessing since its been a little while). The CavArms guys had a few they put 10s of thousands of rounds through and they should be GTG.
Link Posted: 9/25/2013 3:23:16 AM EDT
Originally Posted By AR_George:
Well I just machined an "EP Lower" 80% polymer lower receiver, and I'm sitting here looking at it and wondering: How would this thing hold up in a 9mm application?

Has anyone done this?
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Care to share a link for buying info?
Link Posted: 9/25/2013 6:43:29 AM EDT
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Originally Posted By gtfoxy:


Care to share a link for buying info?
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Originally Posted By gtfoxy:
Originally Posted By AR_George:
Well I just machined an "EP Lower" 80% polymer lower receiver, and I'm sitting here looking at it and wondering: How would this thing hold up in a 9mm application?

Has anyone done this?


Care to share a link for buying info?


I've got no affiliation, just providing the requested link, and linking a pic from their site.

http://www.eplowers.com
Link Posted: 9/25/2013 3:32:19 PM EDT
You can also get them from Midwest Industries.

Link Posted: 9/25/2013 6:39:46 PM EDT
Where are you getting your 9mm uppers and mags?
Link Posted: 9/26/2013 5:32:44 PM EDT
I think 9mmAR has some RRA uppers, and I see metalform 9mm magazines at several places, e.g., Midway.
Link Posted: 9/26/2013 5:51:08 PM EDT
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Originally Posted By AR_George:
Thanks for the reply; that's encouraging. (I was worried about "egging" the hammer pin holes).

Can you estimate how many rounds you might have put through it?
View Quote

you could ramp the bolt to help with this, the 9mm AR is known for being hard on hammer pins . mine is on a rock river 9mm lower it has had over 2000 rounds through it and shows no ware on the hammer pins the bolt was ramped when it was built. but I do enjoy my 9mm AR and it is cheap to play with on the range as any AR gets
Link Posted: 9/26/2013 6:38:30 PM EDT
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Originally Posted By gunnut284:
When I had a 9mm upper I ran it on one of my CavArms lowers. Worked fine.
View Quote



The nice part about the CavArms or the new GWACS armory lowers, is that you can use the Hahn CavArms 9mm magblock which is VERY nice and fits the magwell like a glove.

http://shop.hahn-precision.com/Cavarms-MKII-9mm-Adapter-C9CRT1009.htm



All Colt upper. CavArms lower with Hahn magblock. Functions perfectly!




Link Posted: 9/26/2013 6:45:15 PM EDT
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Originally Posted By maleante:



The nice part about the CavArms or the new GWACS armory lowers, is that you can use the Hahn CavArms 9mm magblock which is VERY nice and fits the magwell like a glove.

http://shop.hahn-precision.com/Cavarms-MKII-9mm-Adapter-C9CRT1009.htm



All Colt upper. CavArms lower with Hahn magblock. Functions perfectly!

http://i557.photobucket.com/albums/ss12/maleantemalandro/9mm%20AR/d95ceda7_zpsfba324ac.jpg

http://i557.photobucket.com/albums/ss12/maleantemalandro/wd1_zpsebb3e647.jpg
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Originally Posted By maleante:
Originally Posted By gunnut284:
When I had a 9mm upper I ran it on one of my CavArms lowers. Worked fine.



The nice part about the CavArms or the new GWACS armory lowers, is that you can use the Hahn CavArms 9mm magblock which is VERY nice and fits the magwell like a glove.

http://shop.hahn-precision.com/Cavarms-MKII-9mm-Adapter-C9CRT1009.htm



All Colt upper. CavArms lower with Hahn magblock. Functions perfectly!

http://i557.photobucket.com/albums/ss12/maleantemalandro/9mm%20AR/d95ceda7_zpsfba324ac.jpg

http://i557.photobucket.com/albums/ss12/maleantemalandro/wd1_zpsebb3e647.jpg


That does look nice. I just ran mine with the standard RRA block and didn't have any issues but the cam pin retention method didn't inspire confidence. I was always afraid it would crack the sonic weld on the front of the magwell (though it didn't).
Link Posted: 9/27/2013 5:23:58 PM EDT
Poly lower is probably fine assuming all else is right.

Poly FCG can be problematic in some cases with 9mm builds. I found that out today the hard way. I tried a poly FCG from a NFA lower in a DDLES lower today and they are at least not compatible with my ramped bolt. Hammer sear would catch, but disco would not. I just wanted to find out if it would run.... and I found out

evl....
Link Posted: 10/2/2013 7:46:14 PM EDT
Cavarms (or now Gwacs) is the only plastic lower I would own, much less use for 9mm. They are not the same as the plastic lowers that pretend they are the same as metal lowers.
Link Posted: 10/2/2013 7:50:42 PM EDT
[Last Edit: 10/2/2013 7:51:05 PM EDT by SinistralRifleman]
Link Posted: 10/2/2013 7:59:18 PM EDT
[Last Edit: 10/2/2013 8:00:46 PM EDT by SinistralRifleman]
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Originally Posted By gunnut284:
That does look nice. I just ran mine with the standard RRA block and didn't have any issues but the cam pin retention method didn't inspire confidence. I was always afraid it would crack the sonic weld on the front of the magwell (though it didn't).
View Quote


The only mag wells that ever cracked were manufacturing defects from not being welded hard enough or the weld area was contaminated. If a receiver failed it did so almost immediately, not hundreds or thousands of rounds into its service life.

Where as CAV would run receivers once a year, GWACS runs them regularly so they have the vibration welding processes dialed in much better than we did at CAV Arms. The GWACS receivers are better made with better QA.


Link Posted: 10/3/2013 5:16:12 AM EDT
My favorite 9mm AR was one I built with a Cav Arms lower. I used a RRA mag wel adapter which once adjusted ran 100%. That rifle was well balanced, light, and fit well. I sold off some of the upper parts but kept my Cav Arms lower. My only regret was not buying a couple more colors. Maybe I can add a FDE one later...I love the Cav lowers.

Do NOT compare the NFA or ATI or other plastic lowers to the Cav Arms (I now...they have a new name now...but I am old and just know Cav who developed them). The Cav Arms lower was designed to be made of the material it was produced in. They didn't do a copy of a lower designed for metal as they are two different materials with different properties. I do run a ATI Omni lower on a budget .22 build and for that use its OK. But NO WAY would I build a 9mm on the Omni, I think it would not withstand the beating. I could be wrong but ..... I don't want to take a chance.
Link Posted: 10/3/2013 5:32:09 AM EDT
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Originally Posted By SinistralRifleman:


The only mag wells that ever cracked were manufacturing defects from not being welded hard enough or the weld area was contaminated. If a receiver failed it did so almost immediately, not hundreds or thousands of rounds into its service life.

Where as CAV would run receivers once a year, GWACS runs them regularly so they have the vibration welding processes dialed in much better than we did at CAV Arms. The GWACS receivers are better made with better QA.


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Originally Posted By SinistralRifleman:
Originally Posted By gunnut284:
That does look nice. I just ran mine with the standard RRA block and didn't have any issues but the cam pin retention method didn't inspire confidence. I was always afraid it would crack the sonic weld on the front of the magwell (though it didn't).


The only mag wells that ever cracked were manufacturing defects from not being welded hard enough or the weld area was contaminated. If a receiver failed it did so almost immediately, not hundreds or thousands of rounds into its service life.

Where as CAV would run receivers once a year, GWACS runs them regularly so they have the vibration welding processes dialed in much better than we did at CAV Arms. The GWACS receivers are better made with better QA.




That's good to hear. I was starting to use mine (which I picked up a while before) right around the time of the CavAid situation and a few cracked welds were being reported. Mine were much older, closeouts from Armalite, that I stuck in the back of the safe. I really like the CavArms lowers for a solid lightweight setup.
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