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Old April 12, 1999, 06:14 PM   #1
Phil in AK
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Join Date: March 17, 1999
Location: Alaska
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Is there a difference in the bolt carrier assembly between a AR-15 and the M-16?
I have purchased two used, legal, semi auto AR's but the guts in one looks different. There is something "clamped" on to the bolt carrier assembly and is slid forward enough that the hammer hits it when fired and will not continue to the firing pin until I pull the charging handle.?? Anyone have a clue, cause I dont! Thanks in advance Phil
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Old April 12, 1999, 11:39 PM   #2
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Yes, there is a difference between the AR-15 and the M-16 internals. You should check out and look at their "AR-15 Vs M-16: parts you shouldn't have in your gun!" or something along that line.

As far as the bolt carrier goes: the M-16's bolt carrier has to trip the auto sear when it slams into battery, so the hammer cutout is the same length on the bottom as it is on the top. On AR-15's that cutout extends much further to the rear, or in the case of some Colt's, this cutout extends all the way back. If you were to use a semi-auto AR-15 bolt carrier in an M-16, it would not trip the auto sear.

What you describe is totally foreign to me. would almost certainly be able to answer your questions.
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Old April 13, 1999, 10:53 AM   #3
James K
Join Date: March 17, 1999
Posts: 24,160
"Something clamped on the bolt carrier"?

Sounds like someone tried to make an automatic weapon and, when it didn't work, unloaded the gun. This could present legal problems as well as functioning problems. If you can, unclamp the something and see if that solves functioning problem. Then throw the "something" in a deep lake. If you can't do that, buy a new semi-auto carrier and deposit old one in lake.

You should take a good look at that gun make sure the previous owner didn't put in some M16 parts or other illegal stuff.

I agree with Destructo6 that a look at the web site will help. They have pictures of the parts involved.
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Old April 20, 1999, 12:35 PM   #4
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"Something clamped on the bolt carrier"

I have the "AR-15 to M-16 Conversion Book", and what you describe sounds like an adapter that is fitted to an AR-15 bolt carrier, to make it function like an M-16 bolt carrier (for tripping the auto sear).

Follow the advice of others: Thoroughly inspect your AR for M-16 parts, and get rid of any you find. While the "clamp" is not an M-16 part, it probably falls into that gray area, since it's used to convert to full auto.

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Old April 21, 1999, 11:40 AM   #5
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I remember reading in a back issue of SAR where someone had incorporated a "sliding mass anti-bounce weight device" to help cycle the short barreled automatic weapons. This was one of the homemade 'cures' for the problem between short recoiling and light primer striking.
The M16/AR15 design needs to have a certain amount of barrel in front of the gas porting (usually around 4 inches or so) to operate correctly. The method I mentioned from the article states that this is as best a compromise solution and really is to be avoided if at all possible. The actual solution is to use a hydraulic buffer, according to them.
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Old April 23, 1999, 09:39 PM   #6
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Phil, do what is obvious and unclamp the block on your bolt carrier. This was an attempt to give the correct dimension to operate the other illegal parts in your firearm to make it fully automatic.
Be Careful Out There. Hank
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Old April 25, 1999, 04:02 AM   #7
Ken Cook
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Join Date: March 4, 1999
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Lightning Link is right.
This is an aftermarket comversion part intended to modify an AR 15 Bolt carrier to M16 dimensions. If it's the one I'm thinking of, it is held in place with a single allen head screw. Take it off an throw it far far away. Your problem will cease and you will not have to worry about getting busted over a stupid technicality.

Your mind is your primary weapon.
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