Tele Posted April 4, 2021 Report Share Posted April 4, 2021 So recently I decided to grab a M5E1 18inch barrel complete upper from Aero directly. When it arrived I took it to the range and found the last round bho didnt work for the magpul lr/sr25 mags. Along with this it only cycled m80 ball any heavier grains it would not feed. After some research I decided to take it apart and measure the diameter of the gas port on the barrel. Heres where the issues are. 1) the handguard screws were not torqued at all. Not even snug, I could have breathed on my t-bit and loosened them. No loctite no degreasing of the screws, nothing. 2) the gas block was not torqued down nor did it have the typical red loctite. Also the screws and the gas block threads were not degreased. 3) there is no dimple on the barrel to align the gas block and the gas port. So upon reinstall its just a guessing game.( I do not have a bore scope) 4) While the gas port measured in correctly to their specs, it is an incorrect spec. .089 was what they drilled but that is to small for an 18inch .308. You need a measurement of .093-.096. 5) barrel nut missaligned and the notches shaved down so the gas tube fits over the notches. WTF. See picture. All said and done gas port was resized to .093 and passed a 2 round function test.( it was late) reassembled correctly and so far it works. Although I will need to take it apart at some port and dimple the barrel for the gas block. My advice build your own ar 10 upper or buy once cry once and dish out the funds. Quote Link to comment Share on other sites More sharing options...
Windwalker Posted December 20, 2021 Report Share Posted December 20, 2021 I just put one together over the weekend with the same results. The barrel wasn't dimpled for the the gas block, the barrel nut was hand tight and couldn't be timed without shims. The receiver was so out of specs that it probably wouldn't have hit paper, so I lapped it. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 21, 2021 Report Share Posted December 21, 2021 3 hours ago, Windwalker said: I just put one together over the weekend with the same results. The barrel wasn't dimpled for the the gas block, the barrel nut was hand tight and couldn't be timed without shims. The receiver was so out of specs that it probably wouldn't have hit paper, so I lapped it. I've never ever had to lap an Aero M5 upper to get it to shoot great. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted December 21, 2021 Report Share Posted December 21, 2021 I've never seen lapping make a huge accuracy difference, not good enough to see the whole benefit I imagine. I do always lapp uppers, Aero seems to fall in the upper and middle end, most are pretty close to start but a couple have had some healthy flaws. For the money I would rather just lapp it myself anyway, takes the issue off the table in my mind. Had a couple DPMS receivers that flat wore out my AR-15 lapping tool they were so far off, took forever. Quote Link to comment Share on other sites More sharing options...
Windwalker Posted December 21, 2021 Report Share Posted December 21, 2021 (edited) 10 hours ago, jtallen83 said: I've never seen lapping make a huge accuracy difference, not good enough to see the whole benefit I imagine. I do always lapp uppers, Aero seems to fall in the upper and middle end, most are pretty close to start but a couple have had some healthy flaws. For the money I would rather just lapp it myself anyway, takes the issue off the table in my mind. Had a couple DPMS receivers that flat wore out my AR-15 lapping tool they were so far off, took forever. I would have thought the same thing about accuracy until I lapped my PSA receiver and it went from a 2&1/2 inch group to under a inch, so I will lapp every receiver that I buy from now on. Edited December 21, 2021 by Windwalker Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 22, 2021 Report Share Posted December 22, 2021 3 hours ago, Windwalker said: I would have thought the same thing about accuracy until I lapped my PSA receiver and it went from a 2&1/2 inch group to under a inch, so I will lapp every receiver that I buy from now on. That must have been a severely fucked up PSA receiver, if only lapping the forward edge brought you from 2.5" to under an inch. Shows what they're putting out. I've never had a 2.5" group out of any Aero M5 set that I've built - never lapped one of them - and I have a pile of them now. Quote Link to comment Share on other sites More sharing options...
Windwalker Posted December 23, 2021 Report Share Posted December 23, 2021 23 hours ago, 98Z5V said: That must have been a severely fucked up PSA receiver, if only lapping the forward edge brought you from 2.5" to under an inch. Shows what they're putting out. I've never had a 2.5" group out of any Aero M5 set that I've built - never lapped one of them - and I have a pile of them now. I will give Aero credit though and that is that there is zero slop between the receivers. I shot it today and it shoots under a inch moa at a hundred so I am pleased with it and I have no regrets with it. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 23, 2021 Report Share Posted December 23, 2021 On 12/20/2021 at 2:35 PM, Windwalker said: I just put one together over the weekend with the same results. The barrel wasn't dimpled for the the gas block, the barrel nut was hand tight and couldn't be timed without shims. The receiver was so out of specs that it probably wouldn't have hit paper, so I lapped it. So, you hopped in here to talk shiit about Aero M5s, never shot it, and said that you HAD to lap it... You have before and after pics of "what you HAD to lap", by chance? Any proof? I've never had to lap one of those... 1 hour ago, Windwalker said: I will give Aero credit though and that is that there is zero slop between the receivers. I shot it today and it shoots under a inch moa at a hundred so I am pleased with it and I have no regrets with it. ...and that wasn't the case?... Quote Link to comment Share on other sites More sharing options...
Windwalker Posted December 23, 2021 Report Share Posted December 23, 2021 (edited) 9 hours ago, 98Z5V said: So, you hopped in here to talk shiit about Aero M5s, never shot it, and said that you HAD to lap it... You have before and after pics of "what you HAD to lap", by chance? Any proof? I've never had to lap one of those... ...and that wasn't the case?... No I didn't take pics, but maybe I'm wrong. I took the lapping tool and started lapping the front of the receiver and there were several high spots and wouldn't that mean it wasn't true? I'm a novice at building these things, so that's why I'm asking you? I will say this maybe it needs broken in, but my cheap PSA will out shoot it as of now. Edited December 23, 2021 by Windwalker Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted December 23, 2021 Report Share Posted December 23, 2021 1 hour ago, Windwalker said: I took the lapping tool and started lapping the front of the receiver and there were several high spots and wouldn't that mean it wasn't true? Depending, there are degrees of untrue, apply an infinite scale and nothings perfect, in general several high spots when you start lapping is better than all on one side. Quote Link to comment Share on other sites More sharing options...
Windwalker Posted December 23, 2021 Report Share Posted December 23, 2021 (edited) 19 minutes ago, jtallen83 said: Depending, there are degrees of untrue, apply an infinite scale and nothings perfect, in general several high spots when you start lapping is better than all on one side. Well it was more to one side than throughout the front of the receiver. Edited December 23, 2021 by Windwalker Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 24, 2021 Report Share Posted December 24, 2021 I'm not saying that they all come from Aero perfect. What I am saying is that I've never lapped an M5 upper, not once, and never needed to to get it to shoot great. I have 5 or 6 of these things, and they all shoot great. Never had a need to take them apart because they won't shoot, and then find that I needed to lap it... Quote Link to comment Share on other sites More sharing options...
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