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13 June 2015, 07:15 #1Contributing Member
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Gas Port Erosion of AR-15 Barrels
The bore-scope view pictured below shows the gas port of a 20" AR-15 barrel with a rifle length gas system that has not yet been fired.
The next bore-scope view shows a 20" barrel with a rifle length gas system after only 1000 rounds have been fired through it. This view illustrates one of the reasons that certain high-end barrel manufacturers make the extra effort to ensure that the gas port is drilled in the center of a groove.
The shorter the gas system, the more rapid the erosion. The bore-scope view below shows the gas port of a 14.5" barrel with a carbine length gas system after only 500 rounds have been fired from it.
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13 June 2015, 08:26 #2Contributing Member
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Very interesting info.
How much does the metal involved, SS vs 416R for example, affect that erosion? Are those barrels chrome lined? It'd be interesting to see how a melonited barrel would hold up as well.
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13 June 2015, 21:32 #3
That is interesting. I would imagine that a lot of things will have an effect. Cleaning procedures and products, type of metal in the barrel, and possibly even the type of ammo.
Just knowing that this is a 'thing' though is definitely food for though.
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13 June 2015, 23:30 #4
Holy smokes....that's kinda wicked and interesting.
BRUUUHHHH....Do you EVEN OPERATE?!?!
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14 June 2015, 12:13 #5New Member
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What type of barrels? CL, stainless?
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14 June 2015, 14:24 #6
This isn't surprising. All those hot gasses and heat start eroding that gas port starting with the first round. Mag dumps don't help either. Most guys won't notice their ports are opening up because they don't shoot enough lead.
Great pictures Molon.
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14 June 2015, 15:36 #7LEO / MIL
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very interesting
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16 June 2015, 14:35 #8
Luckygunner.com did an article on brass vs. steel-cased ammo a while back. There is some interesting info about barrel & port erosion here:
Brass vs. Steel Cased Ammo – An Epic Torture Test
I agree that most folks will never shoot enough for this to become an issue ... myself included
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16 June 2015, 14:44 #9
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16 June 2015, 17:22 #10
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16 June 2015, 18:35 #11
Is the damage in the direction of travel? IE muzzle up in the photos. Just wondering how much could be attributed to physical damage to the tailing end of the port from the bullet passing it.
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16 June 2015, 21:11 #12
I'm curious to know if LMT's 45 degree gas port drilling on the MRP's reduces the gas port erosion rate.
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18 June 2015, 12:42 #13
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20 June 2015, 08:59 #14Contributing Member
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20 June 2015, 09:00 #15Contributing Member
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