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Posted: 10/23/2025 3:38:38 PM EDT
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Do you like it? I have a bunch of 5.7 V Max. A lot. Been thinking of getting an AR57 upper. How do you have your lower set up? Folding stock? Pics would be nice to get an idea where to start. Thanks |
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It’s setup as a pistol now. It will be going back to a SBR confirmation with a modified M7A1 stock as soon as I get my stamp. Has a BFSIII FCG. I have arthritis but a 50 round mag dump is about 5 seconds. Attached File It’s a keeper. It used to sleep right next to the nightstand. |
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Originally Posted By TC1030: It’s setup as a pistol now. It will be going back to a SBR confirmation with a modified M7A1 stock as soon as I get my stamp. Has a BFSIII FCG. I have arthritis but a 50 round mag dump is about 5 seconds. https://www.ar15.com/media/mediaFiles/594071/61F291F4-DEF6-4847-8F60-5F1A0896A5BB_jpe-3646544.JPG It’s a keeper. It used to sleep right next to the nightstand. Mine is just about the same! I would love to get rid of the 'cheese grater rails' on the sides but back then, such was 'hotness du jour'. The bottom magazine is a gutted out PMag (mine is a cut down Lancer) to contain empties, leaving no trace behind enemy line  .
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| Do Super Safeties and the like work with these? I have an extra Franklin Armory binary system. |
I hated going to weddings. All the grandmas would poke me and say "You're next". They stopped that when I started doing it to them at funerals.
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I cannot answer about the SS. But I think that I had to either modify the hammer or the bolt to get the BFSIII to run properly. Also had to make a short heavy buffer to work with the M7A1 stock. I made it from a carbide tool blank. I also made “T” shaped inserts to weld into the SA bolts to convert them to FA bottom profile so that would work properly with oem autosears. I will see about getting pictures of what I modified. |
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Originally Posted By jaqufrost: My new bolt doesn't fit in my old upper  It was fun. It will be more fun when I get it fitted properly and have the m16 trip working correctly. What doesn't fit? |
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Originally Posted By bigbore: What doesn't fit? Here's a pic. Attached File And the impact point where it wedges and can't go further in. Attached File |
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Originally Posted By jaqufrost: The new bolt is two piece and the front of the bolt is roll pinned to the rear of the bolt. Their is a slight misalignment in the rails the front and rear rides on. So the bolt slides into the upper for the length of the first portion of the bolt and then the second part of the bolt hits the rail and it's stuck. Here's a pic. https://www.ar15.com/media/mediaFiles/57761/1000021034_jpg-3646629.JPG And the impact point where it wedges and can't go further in. https://www.ar15.com/media/mediaFiles/57761/1000021035_jpg-3646630.JPG Interesting. Another one of the bolts we got back in the swap had the same problem. The customer sent it back and it fit/functioned fine in my guys upper no problem. If you want to send me your upper and bolt I can check it out and test it with my FA lower. |
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I think all of the uppers that I had were Gen 1, from right after the sheet metal prototypes. They had unpinned bolts. I checked the bench in the basement and had an extra bolt and some of the weights I used for different length barrels with and without cans. Attached File Don’t have any of the modified buffers at the house. I know used an AR10 buffer body for a shortened pistol extension and for the M7A1 setup. I will take more pictures from the upper assembly next time I am over at the shop. |
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Yes. The Pmag is gutted with the lips cut off to make it a brass catcher. I had another one with the floorplate replaced by a mesh bag. It would hold about 300 pieces of brass. Got rid of it because when it got full it was like a big jingly bag hanging off the bottom of my magwell. Was not happy with the sound nor look. |
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| One of the best running setups I put together was a Spike’s AR9 lower with the ejector removed and a magnet imbedded in the receiver between the magwell and the FCG pocket. The magnet worked like an eddy brake to slow the bolt and almost eliminated brass ballooning. Only ran that setup with the factory Spike’s trigger. |
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Originally Posted By bigbore: Interesting. Another one of the bolts we got back in the swap had the same problem. The customer sent it back and it fit/functioned fine in my guys upper no problem. If you want to send me your upper and bolt I can check it out and test it with my FA lower. |
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I got a 57 upper to build my lowerless AR. If I was getting into an AR 57 today I'd go w/ the CMMG or the Diamondback. And there are good alternatives in the Ruger carbine and the SUB2000. |
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Originally Posted By backbencher: And there are good alternatives in the Ruger carbine and the SUB2000. I’m looking at getting a 5.7 Sub2000 to pair with my FN57 since I would be able to use my FN pistol mags. FYI, there is an original FA bolt and buffer on GB right now. Not mine. Sit down before you open the auction. 
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Originally Posted By TC1030: I’m looking at getting a 5.7 Sub2000 to pair with my FN57 since I would be able to use my FN pistol mags. FYI, there is an original FA bolt and buffer on GB right now. Not mine. Sit down before you open the auction. Originally Posted By TC1030: Originally Posted By backbencher: And there are good alternatives in the Ruger carbine and the SUB2000. I’m looking at getting a 5.7 Sub2000 to pair with my FN57 since I would be able to use my FN pistol mags. FYI, there is an original FA bolt and buffer on GB right now. Not mine. Sit down before you open the auction. Just be aware that the Diamondback, CMMG, & Kel-Tec all use the FN Mk 2 pistol mags - which are different than the new Mk 3 pistol mags. FN waited till 3 other manufacturers had made carbines that used their pistol mag to change it on their new pistol. 
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I sell firearms produced by the finest child labor in the world, be it Filipino, Muslim, Mormon, Arizonan, or Texan.
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Originally Posted By TC1030: I'm looking at getting a 5.7 Sub2000 to pair with my FN57 since I would be able to use my FN pistol mags. FYI, there is an original FA bolt and buffer on GB right now. Not mine. Sit down before you open the auction. |
I hated going to weddings. All the grandmas would poke me and say "You're next". They stopped that when I started doing it to them at funerals.
Sic semper evello mortem tyrannis
Sic semper evello mortem tyrannis
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Originally Posted By backbencher: Just be aware that the Diamondback, CMMG, & Kel-Tec all use the FN Mk 2 pistol mags - which are different than the new Mk 3 pistol mags. FN waited till 3 other manufacturers had made carbines that used their pistol mag to change it on their new pistol. Originally Posted By backbencher: Originally Posted By TC1030: Originally Posted By backbencher: And there are good alternatives in the Ruger carbine and the SUB2000. I’m looking at getting a 5.7 Sub2000 to pair with my FN57 since I would be able to use my FN pistol mags. FYI, there is an original FA bolt and buffer on GB right now. Not mine. Sit down before you open the auction. Just be aware that the Diamondback, CMMG, & Kel-Tec all use the FN Mk 2 pistol mags - which are different than the new Mk 3 pistol mags. FN waited till 3 other manufacturers had made carbines that used their pistol mag to change it on their new pistol. My CMMG uses an AR size CMMG mag that works in standard ar15 lowers. Attached File |
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Originally Posted By alpharph: My CMMG uses an AR size CMMG mag that works in standard ar15 lowers. https://www.ar15.com/media/mediaFiles/233426/IMG_3185_jpeg-3657002.JPG Just took my F5 5.7 upper out which I think is a clone of the CMMG....takes CMMG mags. Damn talk about a fun little package and with an FRT it is the tits! |
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Originally Posted By The_Syndicate: Just took my F5 5.7 upper out which I think is a clone of the CMMG....takes CMMG mags. Damn talk about a fun little package and with an FRT it is the tits! Originally Posted By The_Syndicate: Originally Posted By alpharph: My CMMG uses an AR size CMMG mag that works in standard ar15 lowers. https://www.ar15.com/media/mediaFiles/233426/IMG_3185_jpeg-3657002.JPG Just took my F5 5.7 upper out which I think is a clone of the CMMG....takes CMMG mags. Damn talk about a fun little package and with an FRT it is the tits! Did not know they were doing that, that bolt and carrier do indeed look like a rotary delayed system. |
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Originally Posted By SSTPAC: Have any of you guys with 5.7 rdb uppers either cmmg or f5 had any ejector issues? the pistol cal rdbs are plagued with them but nobody has ever said anything about the 5.7s F5 5.7 upper - Just got it a few days ago and slapped it on one of my SBR lowers that I put a Partisan FRT in. Ran 3 32 round mags consisting of 1 mag each of FN SS197, FN SS198LF, and Fiocchi HP 40gr black tip HP. Zero issue unsuppressed. 1 mag of Fiocchi 62gr subsonic suppressed - zero issue. 2 mag dumps of the SS197 suppressed with the FRT - zero issues. All without cleaning or lubing the upper. So no ejection issues. I also picked up a CMMG 5.7 to 22 conversion kit and run 3 mags through it. 2 jams out of 3 mags, but it is was CCI 22 quiet ammo that is lower power than the quiet ammo with Semi Auto on the box so I chalked the issue up to that. Attached File |
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