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Posted: 10/9/2016 1:46:22 PM EDT
| My gunsmith said lapping the upper would make it shoot more accurate. My question is it necessary for a retro build. I can see it being necessary if you're building a competition rifle, but a retro? How many have done it to theirs. The upper receiver is a new brownells manufactured a1 upper. |
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What is he specifically suggesting to lap? The barrel? The upper receiver itself....meaning the bolt carrier bore in the receiver?
If he's thinking the receiver, i've never heard of doing that. If he is talking about the barrel, I certainly would not consider that until the barrel showed properties that would warrant such a procedure. A barrel that exhibits excessive copper fouling.....more than normal fouling... might be a candidate for fire lapping. Why would he suggest lapping even before you know how the barrel behaves? Almost all barrels from makers that produce "match, benchrest, competition,.....however you want to describe top quality barrels, will lap them at some point of the process. It would normally be after reaming, and prior to rifling. Iapping a barrel after it is finished is normally reserved for barrels that have already proved themselves to be of mediocre (sp) quality. Don't do it would be my suggestion. Maybe look for a different gunsmith too. |
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Quoted:
He may be talking about the face of the upper where it interfaces with the barrel extension. Still unless your maxing out your windage or elevation no need for that. Besides removing anodize will hurt value in the future. This is correct. You lap it to make sure the face is absolutely flat/perpendicular to the ring on the extension.. It's easy to do. The tools cost around $20. It's not something I would be concerned about with a Retro AR. It's not like you are building an SPR or something |
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Quoted:
This is correct. You lap it to make sure the face is absolutely flat/perpendicular to the ring on the extension.. It's easy to do. The tools cost around $20. It's not something I would be concerned about with a Retro AR. It's not like you are building an SPR or something Quoted:
Quoted:
He may be talking about the face of the upper where it interfaces with the barrel extension. Still unless your maxing out your windage or elevation no need for that. Besides removing anodize will hurt value in the future. This is correct. You lap it to make sure the face is absolutely flat/perpendicular to the ring on the extension.. It's easy to do. The tools cost around $20. It's not something I would be concerned about with a Retro AR. It's not like you are building an SPR or something It is not something I've ever found necessary with my competition rifles, and I happen to have earned a Distinguished Rifleman Badge. It ain't bragging if you can do it, as Dizzy Dean famously said, but I'm not bragging there, just saying, if it mattered, I'd have noticed it. Lapping in the lugs on a precision bolt gun, yes, but not an AR-15. |
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Quoted:
He may be talking about the face of the upper where it interfaces with the barrel extension. Still unless your maxing out your windage or elevation no need for that. Besides removing anodize will hurt value in the future. This. It is something that is generally not needed unless the upper is out of spec. I know of people that have done it to fix an upper before but never just because. |
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The few times I've used a upper reciever lapping tool (Brownells 080-000-182WB AR-15 Lapping Tool) was when the barrel nut would not line up with the gas tube hole within the specs of 30-80 ft pounds. I've had two DPMS C7/A1E1's and one PSA flat top recievers present this problem. ALL three where paired with Del-Ton Barrels. Not nocking any of the companies. Just seemed to happen that way. The rifles all turned out with happy and productive lives.
The Brownells tool nomenclature states "Helps ensure precise mating of barrel and receiver for added accuracy." So maybe thats the mantra your gunsmith is parroting. 
Hope this helps. |
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