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AR-15 Fired with Black Magic

Only Cemetery would be crazy enough to work up a load for the AR-15 in black powder. Just keep scrolling. Looks like the black doesn’t quite have the energy to cycle the action, but I just think it’s great to try it at all.

UPDATE: Looking at this a bit further, it looks to me like the black powder isn’t even providing the recoil system with enough gas to unlock the bolt. I’m wondering if a heavier bullet would help force more gas back into the gas system? I don’t know much about the characteristics of black powder, so I’d be reluctant to make suggestions, but to me it looks like there’s just not enough gas pressure in the system. If you were getting enough gas pressure in the system to unlock the bolt, you’d just get a short cycle, so I don’t think the buffer spring is really an issue here. The issue here is that you need a bolt that takes less force to unlock, and that’s an inherent design characteristic. Could be the black just doesn’t have the energy to work an AR-15 gas system.

13 Responses to “AR-15 Fired with Black Magic”

  1. And yet .22’s can move their bolt on a conversion kit. I did find a reduced power buffer spring, it’s only $15 or so, and that just means I’ll only be able to get four drinks in NYC instead of five.

    Pretty sad that an AK can go on black, but an AR can’t. Guess we can finally put the AK vs AR tinkling contest to rest.

  2. TS says:

    Gun control may get the idea to ban smokeless powder from this. No point in banning flash suppressors that “allow the shooter to remain concealed at night” when smokeless powder allows them to remain concealed during the day.

  3. “And yet .22′s can move their bolt on a conversion kit.”

    All the .22 conversion kits I’ve seen are direct blowback and don’t use the gas system.

    You probably aren’t getting enough gas pressure to cycle the action. I was going to suggest a grade of black with more oomph, but fffg 777 is pretty stout as substitutes go. You’re probably going to need to drop buffer spring and buffer weights next, maybe step down to the rifle weight parts from carbine parts. Also clean the hell out of the gas system, because I could definitely see the gas block and barrel port getting clogged with crud.

  4. FatWhiteMan says:

    Any idea how fast these loads are travelling?

  5. Jeff the Baptist: I was thinking of tinkering with the buffer spring, I did find a reduced power spring, but if it gets too reduced, I’m concerned that there won’t be enough umph to cycle in the next round.

    Thoughts?

  6. Sebastian says:

    Is it short cycling or is the bolt remaining locked in the breech?

  7. FatWhiteMan: My guess would be at least 2/3rds less of regularly loaded .223.

  8. Sebastian:

    It was short cycling.

  9. Sebastian says:

    Ah, OK… then it might be the buffer spring then. That means you’re getting enough gas pressure to unlock, but it’s just not got enough energy left to give it more oomph. I’d try a heavier bullet, and clean out the gas system completely. If you go to the range and fire some normal ammo through it it should help with cleaning it out.

  10. Sebastian says:

    Also, a heavier bullet might help.

  11. Sigivald says:

    Might also try a longer barrel?

    Carbine-length gas system vs. rifle-length gas system could change the operating characteristics negatively, I’d think.

    BP burns slower than smokeless, right? Thus it’d take longer for the pressure curve to get up, and thus a longer barrel would get you higher pressures, if I’m thinking it through correctly.

    (Plus I somehow like the idea of an original-M-16 configuration firing BP rounds more than an M-4gery doing so.)

  12. Matthew Carberry says:

    So do we give Turtledove credit for picking the right weapons system for “Guns of the South”?

  13. Thomas says:

    Black powder burns much much faster than smokeless powder. In fact, it doesn’t even burn, it explodes. The black powder load will reach it’s maximum pressure much much quicker than the appropriate smokeless cartridge.

    The problem comes down to making the load hot enough to cycle the action without exceeding the maximum pressure spec for the chamber. I don’t think it can be done safely without relocating the gas port much closer to the chamber. Even then, I’m skeptical that an appropriate muzzle velocity can be reached without reaching unsafe pressure levels.

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