technical question about semi-auto assault rifle (related to CO shootings)

[shireen]

According to news reports, the gunman used an AR-17 semi-auto assault rifle. In an LA Times article, the following was said:

Oates said Holmes had also purchased several magazines on the Internet for the assault rifle, including one 100-round drum magazine which was recovered from the scene. With the drum magazine, the gunman could have shot 50 to 60 rounds within one minute.

(source: http://www.latimes.com/news/nation/nationnow/la-na-nn-colorado-shooting-20120720,0,5725827.story)

My understanding of semi-auto weapons is that each bullet is fired by the pull of the trigger. So, even with a 100-round magazine, is it physically possible to fire 50-60 rounds in a minute?

Apologies if this question is too basic or naive for this group, I've only used revolvers--never been quite taken to using semi-autos because i like the simple and basic mechanics of revolvers.

[rrneck]

1. Reasonable discussion is always welcome.

Wiggle your right index finger. That's how fast you can shoot.

[shireen]

6. i was wondering about resistance in the trigger

Is there a mechanism that reduces it, allowing the 'wiggle your right finger' discharge rates?

I don't have very strong fingers ... i can feel some fatigue after firing my gun a few times.

[HALO141]

7. What are you shooting?

Some firearms, particularly some handguns, have abysmally horrendous triggers with long, heavy trigger pulls. Some have short, light ones. I've never experienced a AR trigger that was particularly fatiguing though most of them do exhibit a fair amount of creep as they come from the factory.

[Callisto32]

9. RRA National Match.

Awesome trigger, ~$100.00....if you can find one.

[shireen]

13. S&W 686

Gorgeous hunk of metal! I love it.

But in response to the question about trigger resistance, it could be that my fingers are weak. I don't think it's the fault of my 686, which is a really fine machine. A regular guy would probably be able to fire the entire chamber continuously without feeling any finger fatigue.

[ManiacJoe]

17. You may just need to get the trigger smoothed out.

The smoothing will probably make it a little lighter, but smoother is the important part. (I need to do this with my 686.)

Semi-autos will fire just as fast as you can pull the trigger. 60 per minute is easy to achieve. However, actually hitting your target while doing it is a very different thing.

[MicaelS]

37. Sounds like you need a trigger job on your S&W 686.

Last edited Wed Jul 25, 2012, 01:19 PM - Edit history (1)

Below is an explanation of what would be done. But this is something you would only want a gunsmith to do. I would recommend you Google for a gunsmith in your zip code, and then contact them for pricing. Don't go overboard, and let them talk you into a bunch of work you don't need. You could easily spend as much on gunsmithing as the gun is worth.

EDIT: I wanted to strongly emphasize that you should let a professional do this. Not that an amateur can't do it, but rather for safety and liability concerns. You want the gun to operate safely and smoothly. And, if you ever have to use the gun as a defensive weapon, you don't want some lawyer trying to prosecute or sue you because you turned the gun into a "hair-trigger weapon".

[rrneck]

16. I dunno.

I expect it depends on the gun. Some guns have adjustable triggers, but I would expect most of them to be about the same. Probably between three and seven pounds or so.

[HALO141]

2. No, it's possible. If...

If you're not concerned with aimed fire, it's possible to press the trigger that quickly.

[Kaleva]

20. One can accurately fire a M-1 Garand, with an 8 round internal mag, about 16-24 rounds a min.

That's according to FM23-5
http://myplace.frontier.com/~aleccorapinski/id13.html

I've read in some sites that the rate of fire for an M-1 could be doubled if one isn't concerned about accuracy.

[alabama_for_obama]

28. supposedly an english small arms trainer during WWI

fired his .303 british service rifle (bolt action, 10 round magazine) 37 times on target (12" at 300 yds.) in 60 seconds. some accounts claim 38.

60 rounds in 60 seconds from a semi auto ought to be a piece of cake for someone with some skill, given that they would only need to reload once.

[immoderate]

3. It's not an assault rifle it's an assault weapon.

Assault rifles are full auto, or at least bursts. Assault weapons have certain attachments, none of which, except high capacity magazines, affect its lethality. Pistol grips, spark arrestors, and skeleton stocks are the usual attachments.

And any semi-auto can fire a bullet a second. And I think it was an AR-15.

--imm

[shireen]

11. terminology

Yes, Holmes used an AR-15. From what i've read, it is a modified version of the military M16 assault rifle.

Question: are the terms you mentioned above, assault rifle vs. assault weapons, technical definitions or political definitions?


I'm not looking to stir up any trouble. I don't follow gun control issues closely, so the purpose of my questions are to understand the basics of a very controversial issue. That way, I don't inadvertantly use the wrong term and make someone mad.

[immoderate]

21. Assault rifles are generally not sold to the public, illegal since 1935.

That's why you can't buy a machine gun. Assault weapons have mostly cosmetic additions, except the big magazines. That's the level of my expertise.

--imm

[ozone82]

32. Not True.

It is legal in most states to buy them. Fill out the paperwork, $200 fee plus cost of the weapon. Takes about 4-6 months for the background check to be done, clean record, good to go. None may be sold that were made after May 1986 IIRC. You see many for sale in the gun stores in Las Vegas.

Saw a Thompson Model 1928 at The Gun Store in 2009 for $15,000. Another had a Viet Nam era M60 MMG for about $20k. Think about 45 or so states allow it. They are however, very costly.

[gejohnston]

23. assault rifle is a technical term

http://en.wikipedia.org/wiki/Assault_rifle

assault weapon is a political term
http://en.wikipedia.org/wiki/Assault_weapon

[PavePusher]

24. A few things....

"assault rifle" is a legal definition for a fully automatic firearm (machine gun). Some people deny this, but the BATFE doesn't screw around if you have an unregistered assault rifle in your possesion. Federal jail time would be in your future.

"assault weapon" is largely a political term used to make certain firearms sound like they are fully automatic (machine guns) when they are not. It's intended to sell "FUDD" (Fear, Uncertainty, Doubt), in an effort to obfuscate people who are not familiar with firearms. ( http://en.wikipedia.org/wiki/Josh_Sugarmann )

An AR15 is not a "modified version of the military M16 assault rifle", although it is derived from one. It is purpose-built without the full-auto firing capability, and the design was deliberately changed after the 1986 law changes to make it difficult to convert them to full-auto (you'd actually have to add metal to the interior, a much more difficult proposition than milling out excess metal).

More info here: http://en.wikipedia.org/wiki/National_Firearms_Act


Hope this helps, please ask if you need anyadditional information, we love to lecture around here. Teaching is FUN!

[discntnt_irny_srcsm]

44. I noticed that...

...the Wikipedia page on Mr Sugamann neglects to mention his FFL.

[MicaelS]

4. Yes it is possible to fire 50-60 rounds in a minute..

To better understand how AR-15 pattern rifles operate, see these animations on YouTube.

[shireen]

5. thank you! That's fascinating

and quite amazing to realize the amount of power packed in such a small space!

[gregoire]

8. You really have to wonder why those videos haven't been banned yet

Google has sensible policies wrt videos that teach how to make bombs. Why do they ignore the danger of machine guns?

[Callisto32]

10. Srsly.

Google should try to put a cork on 140+ year old tech?

Jeeze, you sound like the folks that ask "why do you carry a KNIFE?"

ETA: Also, if one is too stupid to figure out that bombs can be made out of nearly anything, will he really be smart enough to go on the internet and figure out how to make one that requires instructions?

[krispos42]

45. Those same people...

...are generally pleasantly surprised to have me pull out my knife and offer it to them when they need to open a box or something.

[NewMoonTherian]

12. Those are hardly instructional videos.

Besides, those both depict semi-auto guns, which are perfectly legal. Also, Google censoring results isn't sensible.

[shireen]

14. why ban those assault rifle videos?

It's just an animation describing how guns work. Basic mechanical physics. It's not teaching anyone how to run off and make one in the garage.

[PavePusher]

22. Luddite, much?

Sheeeeeeesh.....

[permatex]

25. Seriously

why would you come here and disrupt a civil conversation? OP was asking pertinent questions and looking for info.
Go away and let the grownups have a discussion.

[jeepnstein]

15. As a practical matter the 100 rounders are useless.

I'm seeing media reports that the 100 round magazine failed to feed, which caused the gunman to call it quits early. That's why they're not more commonly used. They are a useless novelty item that can't be trusted to feed reliably. Same goes for those extended Glock magazines, they are useless junk. That's why the military uses belt fed machine guns when capacity is an issue.

Yeah, it would be easy enough to fire a round a second until the weapon failed to feed. Hitting anything would be a spray and pray kind of proposition. Not that it would really matter that much in a crowded theater.

My State, Ohio, has limits on magazine size so the 100 rounders aren't seen here at all. We have a thirty round limit, which coincides with the standard magazine issued to the military.

[tortoise1956]

42. I am NOT and expert,

But I have a buddy who's pretty knowledgeable on weapons. He claims that it is damn near impossible for a novice to properly load one of those drum magazines Exact words were,"100-round pieces of crap&quot so that it doesn't jam. As for the extended magazines, I have no idea. Have they said which type he used?

[jeepnstein]

43. What I heard...

is that he tried to use a 100 round Beta mag and it failed to feed, big surprise. He apparently had some 30 rounders with him but didn't use them. My best guess is he never fired an AR15 in his life until that night.

[GreenStormCloud]

18. Easily possible.

60 rounds a minute is only one round per second. There is even time to briefly aim. A second is a fairly long time in that context. Time yourself on how really long a minute is.

[discntnt_irny_srcsm]

19. re: "is it physically possible to fire 50-60 rounds in a minute? "

Is your name Dylan Holsey?


If so, you'd be even faster with a pistol:

and a lever action Winchester:

[Jamesm9164]

26. Fuck this shit

Here we are arguing about nits. This thread is why the discussion will go nowhere until the discussion about the next mass killing.

[discntnt_irny_srcsm]

27. Oh now...

...enough with the naughty words. Surely you can be adequately expressive without them.

[EX500rider]

29. Yes Lord forbid someone try to learn something.....lol n/t

[discntnt_irny_srcsm]

38. Tyranny is best explained...

...by the quote in my sig.

[CokeMachine]

33. What in hell are your talking about??

Someone asked a question and people are answering it. Take a chill pill

[discntnt_irny_srcsm]

36. For some folks...

...there's questions you just can't ask. Who knew?

[Travis_0004]

30. I love this video too

[link:

|

It shows what is possible by a very well trained shooter, in the top .01%

60 rounds per minute is certainly doable with the average shooter. The gun is capable of cycling at 600+ rounds per minute, so when you pull the trigger, it will be ready to fire.

[gejohnston]

31. since you like revolvers

five rounds in about half of a second.
http://en.wikipedia.org/wiki/Ed_McGivern

[Kaleva]

34. One can fire 30 rounds in about 3 seconds with bump firing

[AtheistCrusader]

39. That was 20 rounds, if you count it (and he didn't hit a fucking thing he was aiming at.)

[Kaleva]

40. If one just wants to spray lead into a crowded, dark theater, one doesn't need to aim.

[AtheistCrusader]

41. Eyewitness accounts from Colorado disagree.

[benEzra]

35. I shoot competitively with an AR-15 and a Smith & Wesson 5906...

and 60 rounds in a minute from either gun would be feasible with pretty much any size magazine, from tiny 10-rounders to normal 30's/17's and up. One round per second is not particularly fast for any civilian semiauto rifle or pistol, or a revolver for that matter until you reload, and because an AR-15 is very small-caliber as rifles go (it's a centerfire .22), recoil is not as significant as it would be for a full-power rifle. With a pistol or rifle, I can typically maintain about 2 shots per second including reloads inside 40-50 feet, starting from the buzzer, and stay in the A zone.

The limiting factor as to how fast you can drive any civilian 1-shot-per-trigger-pull firearm is how fast you can use the sights, not how fast you can pull the trigger. It is entirely possible to shoot an ordinary pistol or rifle at a rate of five or six shots per second, but you will not hit unless you slow down and aim. I run an Eotech holographic sight on my rifle, and I will tell you that the big difference between a semiauto Remington Model 1908 of 100+ years ago and a modern AR isn't rate of fire, it's the sighting systems available.

Having said that, the worst mass shootings in the United States (Luby's, VT) involved very slow, deliberate fire with ordinary pistols at close range, and lots of reloading (I believe the VT shooter reloaded at least twelve times). There tends to be an inverse correlation between speed and lethality.

[krispos42]

46. Yeah, you can.

Find yourself a clock with a second hand, or a blinking digital display. Hold a stick up to your shoulder and say "bang" each time the clock ticks/blinks.


You can't really do a precise amount of aiming, but for what Sideshow Bob was doing (packed crowds at close range) you can just point the gun and shoot. The recoil is mild and the rifle won't jump too much.


You can shoot really fast with a revolver, too. Jerry Miculek can fire 8 shots from a revolver in I believe 1.00 second.