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AR

sophienchloesdadsophienchloesdad Member Posts: 1 ✭
in Ask the Experts

Will an aluminum lower match up with a polymer upper

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Comments

  • mark christianmark christian Member Posts: 24,443 ✭✭✭✭

    As long as both components are MILSPEC there's no issue matching them.

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  • MobuckMobuck Member Posts: 14,132 ✭✭✭✭

    As Mark said, IF(?) both components are within spec, they should fit together.

    BUT what I've seen with some of the polymer products is considerable variance in key areas such as distance between pivot pin and takedown pin/rear lug and the area where the upper receiver meets the buffer tube recess.

    Is this due to tolerance stacking, temperature expansion/contraction issues, or just poor quality control? I DUNNO but it's a bit frustrating to have to go through a stack of uppers and lowers looking for proper fitting pairs. When I assemble an AR, I start by matching upper and lower and then move to barrel extension to upper fit before continuing to the actual assembly.

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  • chmechme Member Posts: 1,471 ✭✭✭✭

    Don't know- but would opine they may not.

    I have a BushMaster CARbon-15. Carbon fiber gun. It does NOT disassemble the way the MILSPEC metal AR does.

    You know that "pull the rear pin, shotgun the rifle" thingy? Won't work. You pull the front pin, then lift UP on the front of the upper.

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