School me on AR-pattern rifles

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Erik
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Re: School me on AR-pattern rifles

Post by Erik »

toad wrote:Erik:
Can civilians get bolt action rifles with large capacity magazines, 20 to 30 rounds, in military calibers :?:
Probably. It's no problem getting bolt action hunting rifles in military calibers with detachable magazines. Max allowed capacity is 5 rounds. But magazines in themselves aren't restricted, so you could buy high capacity mags if you can find them. You just cant use them for hunting. (The law is a bit fuzzy, I think technically you could use them as long as you only load them with 5 rounds, but I'd rather not try to argue that with the police or courts.)

The magazine capacity limit is the same for bolt action as well as semiautomatic rifles. However semi automatic rifles for hunting must be similar in look and function to bolt action rifles (except the loading mechanism). AR type rifles aren't allowed for hunting. (The Mini 14 is also impossible to get a license for now.) My guess is that to have a semi automatic hunting rifle it has to be a rifle that was made with the intention to be a hunting rifle, and which looks like a hunting rifle.

I think the question would hinge on what rifle it is. I cant see how it would be a problem with a Remington 700, a Tikka or a Sako, but if you tried it with a military style rifle that took AR mags you would probably run in to some problems.

The magazine capacity issue has been up for discussion here as well, but so far it hasn't gotten any real traction. It's just too complicated to implement, since there's been no restrictions at all so far. (You could buy any magazine you want, regardsless if you even have a gun or not.)
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Erik
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Re: School me on AR-pattern rifles

Post by Erik »

JAG2955 wrote:So basically, you get/build one, then you say "man, it sure would be cool to build one with XYZ part, and ZYX part, and...."
Or you buy a complete one, and then after shooting it for a a while you go "it would be great to have a different stock, and maybe a better trigger, and a different grip, and ......"
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Netpackrat
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Re: School me on AR-pattern rifles

Post by Netpackrat »

I'm not sure I fully understand the purpose of the gas rings on the bolt... They say the bolt is supposed to be like a piston, but it's the motion of the carrier that causes the bolt to unlock and move rearward, caused by the gas impinging on the gas key. What am I missing?
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JAG2955
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Re: School me on AR-pattern rifles

Post by JAG2955 »

Netpackrat wrote:I'm not sure I fully understand the purpose of the gas rings on the bolt... They say the bolt is supposed to be like a piston, but it's the motion of the carrier that causes the bolt to unlock and move rearward, caused by the gas impinging on the gas key. What am I missing?
The gas enters the gas key, and pushes the carrier to the rear by impinging on the rear of the bolt. When the bolt moves forward relative to the carrier, the gas can escape through the gas holes in the carrier that were previously ahead of the gas rings. Eugene Stoner did not like his rifle called "direct gas impingement." He considered it a piston weapon.

For a fun experiment, take your gas rings off your bolt*. You may get a shot or two off, but it will choke sooner or later.

*Funny "mil-spec" story: I have received M16s that had just returned from depot maintenance that DID NOT HAVE GAS RINGS ON THE BOLT.

I also had 7 come to my company with the gas tubes installed UPSIDE DOWN. That takes talent.
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Netpackrat
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Re: School me on AR-pattern rifles

Post by Netpackrat »

That doesn't make any sense mechanically. The bolt is locked, it cannot go farther forward, so pushing against it cannot accomplish anything.
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JAG2955
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Re: School me on AR-pattern rifles

Post by JAG2955 »

Netpackrat wrote:That doesn't make any sense mechanically. The bolt is locked, it cannot go farther forward, so pushing against it cannot accomplish anything.
Inertial frame of reference. I thought it would make it easier to understand.

The gas goes through the carrier key and impacts the tail of the bolt inside the carrier. The gas pushes against the bolt, which cannot move, so the carrier moves backward, which is what unlocks the bolt.
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Netpackrat
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Re: School me on AR-pattern rifles

Post by Netpackrat »

So basically, the carrier acts as a piston, then. I'm not sure what the difference is between that and direct impingement. :lol:
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Old Grafton
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Re: School me on AR-pattern rifles

Post by Old Grafton »

Easier to understand if you think of it as a jumping cylinder on a stationary piston. The piston (bolt) has rings on it just like the piston on a lawnmower engine. The hot combustion gases expand in the cylinder jumping it to the rear while the cam slot rotates the bolt to unlock it (the carrier can't rotate, the gas key in the key slot of the charging handle prevents it) and then the still-rearward-jumping cylinder yanks the now-unlocked bolt along for the ride.
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JustinR
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Re: School me on AR-pattern rifles

Post by JustinR »

Netpackrat wrote:That doesn't make any sense mechanically. The bolt is locked, it cannot go farther forward, so pushing against it cannot accomplish anything.
The way I understand it, as shown at 1:30 in this animation, is that the gas rings prevent the gas from escaping around the bolt. The gas tries to go somewhere, so it continues to expand the other direction and push against the carrier, moving it rearward. I suspect that the gas pressure pushing forward on the bolt helps slow the bolt unlocking until the chamber pressure has dropped to safe levels.

It might be splitting hairs, but "direct impingement" wouldn't have the gas pressure also going forward to perform work. That's probably why Stoner didn't want to call it that. But just a WAG.
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Old Grafton
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Re: School me on AR-pattern rifles

Post by Old Grafton »

Actually the gas pressure does affect the bolt; it delivers forward thrust to break loose the pressure/friction lock of the bolt lugs in the lug recesses. It can't move forward much but it's enough.
I'm not old--It's too early to be this late.
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