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Thread: Colt CM762

  1. #201
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    Quote Originally Posted by call_me_ski View Post
    So has anyone put a 308 receiver extension and used a normal carbine buffer with it? Does that work? Is it advantageous?
    I think you can run an A5 RE with a standard length buffer for 308 and an A5 for 556. I’m just not there yet, as the recoil is down with the BCM Comp it just slings brass. I might work with BRT to get a different gas tube to reduce it a bit but want to shoot it more with the comp after the weather gets tolerable and I can spend more enjoyable time working on it, as opposed to the hot humid as foook range session where I push through the list of things to do and depart ASAP.

  2. #202
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    Quote Originally Posted by Mike Miller View Post
    I have a CM762 and a Dead Air Nomad waiting for a form 4. I would like to reduce the gas flow for 100% suppressed use with a gas block insert. What would be a good gas port size to use? I'm not able to find good data for suppressed 308 gas ports like I can find for 556.
    I was able to shoot it suppressed today. I think it's overgassed. I had a failure to feed on the 3rd round suppressed where the round smashed into the feed ramps and the bullet pushed into the casing. Recoil feels harsh, like the bolt carrier group is bottoming out in the buffer tube, and my ejection pattern is between 1 and 2 o'clock. I don't put much faith into ejection pattern by itself, but combined with the other symptoms it lines up with being overgassed.

    I shot without the suppressor before and after, it shot fine. The rifle is completely stock other than the suppressor mount and optic.

    That said, what's a good gas port size to go to with my Dead Air Nomad? I still plan to shoot 100% suppressed. I have no desire to get an adjustable gas block, I want to use an insert.
    Last edited by Mike Miller; 09-18-20 at 20:35.

  3. #203
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    Quote Originally Posted by Mike Miller View Post
    I was able to shoot it suppressed today. I think it's overgassed. I had a failure to feed on the 3rd round suppressed where the round smashed into the feed ramps and the bullet pushed into the casing. Recoil feels harsh, like the bolt carrier group is bottoming out in the buffer tube, and my ejection pattern is between 1 and 2 o'clock. I don't put much faith into ejection pattern by itself, but combined with the other symptoms it lines up with being overgassed.

    I shot without the suppressor before and after, it shot fine. The rifle is completely stock other than the suppressor mount and optic.

    That said, what's a good gas port size to go to with my Dead Air Nomad? I still plan to shoot 100% suppressed. I have no desire to get an adjustable gas block, I want to use an insert.
    Did you change the buffer or spring. I know I have a LE901 but I changed the buffer and it’s 100%.

  4. #204
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    Quote Originally Posted by TheChunkNorris View Post
    Did you change the buffer or spring. I know I have a LE901 but I changed the buffer and it’s 100%.
    What did you change it to?

    Mine is much better with the BCM 762 Comp in terms of recoil - still a tad overgassed with brass to 2 or so.

    I tried a Red Springco but after awhile it caused short stroking, back with the OEM spring and buffer. Not planning to put a suppressor on it so I'll likely leave it for now.
    Last edited by RHINOWSO; 09-19-20 at 08:28.

  5. #205
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    Quote Originally Posted by TheChunkNorris View Post
    Did you change the buffer or spring. I know I have a LE901 but I changed the buffer and it’s 100%.
    I did not, I'm running the buffer that came with the rifle.

    I pulled the gas block today, the port size was .067", checked with numbered drill bits which were validated with calipers after. According to the data in the below link, that's not a crazy huge gas port
    https://www.tacticalmachining.com/le...ort-sizes.html

    I was surprised to see that the set screws on the gas block had no thread locker on them at all, they turned free by light finger pressure with an allen key. I don't think it was just burned, there's no residue. They're #8-32 set screws instead of the common AR-15 size of #10-32. The pin on the gas block is tapered, and was removed left to right
    Last edited by Mike Miller; 09-19-20 at 12:08.

  6. #206
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    Quote Originally Posted by RHINOWSO View Post
    What did you change it to?

    Mine is much better with the BCM 762 Comp in terms of recoil - still a tad overgassed with brass to 2 or so.

    I tried a Red Springco but after awhile it caused short stroking, back with the OEM spring and buffer. Not planning to put a suppressor on it so I'll likely leave it for now.
    I used a Geissele H3 with their spring.

  7. #207
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    Quote Originally Posted by Mike Miller View Post
    I did not, I'm running the buffer that came with the rifle.

    I pulled the gas block today, the port size was .067", checked with numbered drill bits which were validated with calipers after. According to the data in the below link, that's not a crazy huge gas port
    https://www.tacticalmachining.com/le...ort-sizes.html

    I was surprised to see that the set screws on the gas block had no thread locker on them at all, they turned free by light finger pressure with an allen key. I don't think it was just burned, there's no residue. They're #8-32 set screws instead of the common AR-15 size of #10-32. The pin on the gas block is tapered, and was removed left to right
    I’m sure you can tune it via the port but I’d try a buffer beforehand.

  8. #208
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    What suppressor do you use? Do you run it 100% suppressed? If not, do you change the buffer when unsuppressed?

  9. #209
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    Quote Originally Posted by Mike Miller View Post
    What suppressor do you use? Do you run it 100% suppressed? If not, do you change the buffer when unsuppressed?
    I use both a Knights 762 QDC CQB and a full sized 762 QDC 100% of the time. What got me using the H3 was when I bought a buffer kit for another rifle from LMT and I was told that LMT uses an H3 in the MWS. I’d like to correct my last post, I use a LMT action spring and not the Geissele. This is the kit I purchased for my Colt. The only thing I’d like to add is I have a LE901 and not a CM762 so there could be a chance the port sizes are different but it’s unlikely as the only real difference is the monolithic upper vs a traditional handguard and upper receiver combo. The lowers are the same.


    https://www.titandefense.com/lm308btk.html

    With all that said, I would keep the H3 in there in the event I decided to shoot unsuppressed for whatever reason. I will be properly sighting in my rifle sometime next month so I’ll have more info for you after that gets done.

  10. #210
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    So to be clear, you are using a H3 buffer (longer that the 308 buffer) with a LMT (carbine?) action spring in the OEM RE?

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