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Posted: 12/28/2016 6:48:55 PM EDT
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Hello All,
I am hoping someone can help me with feeding issue my new 9mm build is having. When chambering a round, the bullet hits the barrel just above the chamber entrance. With ASC magazines, i dents the bullet but feeds. With RRA magazines, it hits hard enough to drive the bullet back into the case. The sides of the Magazine and the sides of the feed ramp seem to line up fairly well but the bullet is still coming off at to high of an angle. Can anyone gives me things I need to check or personal experience with the same issue? Thanks Build List PSA Dedicated Colt lower Spinta Precision Ramped Bolt PSA 16" 9mm Barrel Key mod Hand guard Aero Precision Slick Side Upper |
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Sorry for the delay in reply.....little bout of the flu.......but looking at the pics....feed cone on the barrel could definitely use some work......and the feed lip on the magazine shown installed in the lower from the side is deformed.....lip turns up at the end where it should be straight.
What weight and overall length buffer are you using? |
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Quoted:
Sorry for the delay in reply.....little bout of the flu.......but looking at the pics....feed cone on the barrel could definitely use some work......and the feed lip on the magazine shown installed in the lower from the side is deformed.....lip turns up at the end where it should be straight. What weight and overall length buffer are you using? Great observation about the feed lip. You really do know your stuff ! Thanks for helping all of us ! |
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Quoted:
Quoted:
Sorry for the delay in reply.....little bout of the flu.......but looking at the pics....feed cone on the barrel could definitely use some work......and the feed lip on the magazine shown installed in the lower from the side is deformed.....lip turns up at the end where it should be straight. What weight and overall length buffer are you using? Great observation about the feed lip. You really do know your stuff ! Thanks for helping all of us ! If those are RRA/Metalform mags, they look fine - maybe just the older design. Metalform used to offer their 9mm AR mags with straight feed lips and upturned (Uzi style) feed lips. They also offered 2 different followers - delrin and metal. I think they only offer flat feed lips and metal followers currently (and maybe for the last few years). I don't recall if CP/ASC did the same or if they were all just flat lip (they went through more than a few iterations on their mags). I have almost all variations of metalform mags - blued, park'd, delrin followers, metal followers, flat feed lips, upturned feed lips - and they all run the same for me - no issues. ETA - If those are RRA converted Uzi mags, they are also probably fine as I think all Uzi mags are that way - upturned feedlips. I've run converted uzi mags in my builds in the past. The only ones that I had feed issues with were ones were the mag catch was not cut at the correct location. |
Not to start an argument but I have Uzis and Uzi mags and have never seen one like that.....and I have been playing with AR pistol caliber for a while...and from what I have seen the feed lip is malformed.....but again...just my opinion  Only time I have seen one like that is on a modded mag....that had the follower blocked with a pin in one of the witness holes.....and as the pin was pulled it allowed the follower to slam into the lips unrestrained......
Properly set up a 9mm rouns should never touch the feed cone on a barrel at the 12 O'clock position......with the feed angle and the angle of the feed cone it is like driving the round into a flat surface at a 90 degree angle. |
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Quoted:
Not to start an argument but I have Uzis and Uzi mags and have never seen one like that.....and I have been playing with AR pistol caliber for a while...and from what I have seen the feed lip is malformed.....but again...just my opinion Only time I have seen one like that is on a modded mag....that had the follower blocked with a pin in one of the witness holes.....and as the pin was pulled it allowed the follower to slam into the lips unrestrained......
Properly set up a 9mm rouns should never touch the feed cone on a barrel at the 12 O'clock position......with the feed angle and the angle of the feed cone it is like driving the round into a flat surface at a 90 degree angle. No arguments here, just wanted to share info. Of the 2 photos the OP posted, the first showed a mag with orange follower (CP/ASC?) and the second showed a mag with a metal follower (I think RRA/Metalform with upturned feedlips) - I was commenting about the second photo in case there was any confusion. In the below photo, I am not sure which mag the OP has inserted (I think RRA/Metalform), but it appears to have the older/original style upturned feedlips. I don't have many Uzi mags left, but I found one and added it to the top of the pic to show that they came in the same upturned feedlip style. I didn't have time to go through all my Metalform mags in storage to get a pic of the ones with the upturned feedlips and the 6 Metalforms I have out right now are all straight feedlip style. I don't have much experience with Uzi's, but during the many years when Colt mags were $50-60 and up to $100+ per mag, I messed around with converted Uzi mags since they could be had for ~$10-15 each. All of the IMI/MecGar Uzi mags I converted had the upturned feedlips as pictured. I was under the impression that all Uzi mags had upturned feedlips as I don't think I ever saw an Uzi mag with straight feedlips. But that's just my experience - I have no idea how many version of Uzi mags are out there though and which feedlip style was actually the more common one. 
I believe it has been years (at least 5+) since Metalform offered their mags in multiple versions with both flat and upturned feedlips. Based on the pic on the RRA website, it looks like they show the upturned feedlip style. 
ETA - All of my builds have RRA or Spinta barrels, RRA or Spinta bolts, and Hahn or KAK blocks and they all work with Metalform or Uzi mags with flat or upturned feedlips. If the PSA lower or barrel is too far off from Colt spec, perhaps that is why OP is having feeding issues. I believe PSA and Brownells are only selling the flat feed lip Metalforms these days, so maybe try those and see if they work better than the RRA/Metalforms with upturned feedlips. |
| The Mag pictured with a black follower is RRA and the orange is ASC. I ordered a metalform mag from PSA and the issue improved. The PSA Mag sits a few hundredths of an inch higher in the magwell and have a flatter follower angle. Now there are some rounds that do not hit at all and others that have a small ding on the bullet. I called PSA and they said the buffer is 5.5 ounces with a standard carbide spring. Im thinking about ordering the heavy KAK buffer and AR10 spring to slow things down some and see if that helps. |
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