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Author Topic: Bushmaster XM15 not Cycling with .223  (Read 522 times)

289ace

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Bushmaster XM15 not Cycling with .223
« on: January 18, 2021, 12:54:18 pm »
I am primarily a Mil Surp/Old gun guy but decided to try living on the dark side and recently bought a mid '90s Bushmaster XM15 with a 20" barrel that does not look like it has been fired much. On my first outing it initially ran through approx 10 rds of .223 and then I tried a different mag (both mags were new) and had am immediate failure to feed. The round will load with the charging handle, eject after firing, but will not load the next round. I went back to the original mag and now it wasn't feeding either.  A buddy gave me some XM193 (55 gr 5.56) and I was able to run another 10 rds without a problem. Another buddy gave me some green tip (62 gr 5.56) and it wouldn't cycle.

I took it home and did a thorough cleaning of the bolt and innards and then reoiled it in a very liberal manner. I took it back out this morning and it still will not feed with my 223 so I think it is short cycling.

At this point it seems the Bushmaster is very finicky and I was wondering if anyone has any experiences with running 223 in an earlier XM15. I have a fair amount of 223 on hand, but have no 556 so I am hoping I will be able to figure out how to shoot 223 through it until 556 become available again.

Questions for the brain trust are, and please remember I am a neophyte to this black rifle stuff so may be using the wrong terms-
1. Would a change in the buffer spring help with what I think is short cycling? If so, how do I know what my current spring rate is?
2. How can I check the gas port? Can I run compressed air though it to confirm it is clear?
3. Are there any surfaces I can polish to free things up a bit?
4. Is there anything else I should be looking at?

TIA for any help and suggestions

ArizonaGunOwners.com

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    1911_username

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    Re: Bushmaster XM15 not Cycling with .223
    « Reply #1 on: January 19, 2021, 04:08:42 pm »
    I would check the gas block to see if it's loose or fouled. Sounds like your  having a gas issue. I had similar issues with an older XM barrel. Come to think of it, I had to get the gas port tapped larger.

    289ace

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    Re: Bushmaster XM15 not Cycling with .223
    « Reply #2 on: January 21, 2021, 07:28:46 am »
    I would check the gas block to see if it's loose or fouled. Sounds like your  having a gas issue. I had similar issues with an older XM barrel. Come to think of it, I had to get the gas port tapped larger.

    Thanks! I'll make sure I check out the gas block and all the passages when I tear it down.

    JB99er

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    Re: Bushmaster XM15 not Cycling with .223
    « Reply #3 on: May 08, 2021, 09:37:07 am »
    Similar problem...
    Wound up being a gas leak between the bolt carrier key and the bolt carrier. Had it fixed. Now staked.

    Nevahhappen

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    Re: Bushmaster XM15 not Cycling with .223
    « Reply #4 on: May 15, 2021, 01:10:57 pm »
    Did yu ever figure this out?

    On my first LR-308 build, it would not lock back on an empty magazine and sometimes not feed.  Was confusing as I had also built with an adjustable gas block. 

    Since I had built it, no fears of tearing it back down.  Running a drill bit through the gas port knocked out a burr.  Back together and it shot great and responded to the gas adjustments as intended.

    ArizonaGunOwners.com

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