POF Roller Cam

[skyugo]

Ok. I get where your coming from, in the technical sense. But, don't you think Stoner might have thought he finally got it the way be wanted it.

engineering never works like that. Everything is a compromise, and when you're working on a time sensitive project trying to win a military contract that's a part of the compromise. I do think it's a very good system and it really is the first modular adaptive rifle. This roller cam thing is neat, but i'm not interested in beta testing it.

[vicious_cb]

http://www.youtube.com/watch?v=6JmIQXkoog8

Here is a interesting video, may show a argument for the use of the POF roller cam pin.

Not this guy again, his "test is full of BS. The AR doesnt work like that. There's this thing called a gas system that provides the P-V work, not gravity or finger movement. Regular cam pins work fine, just replace them at regular intervals. A "smooth" hand cycling AR doesnt mean shit, Ive held plenty of perfectly reliable ARs that hand cycled roughly.

[brent31]

Not this guy again, his "test is full of BS. The AR doesnt work like that. There's this thing called a gas system that provides the P-V work, not gravity or finger movement. Regular cam pins work fine, just replace them at regular intervals. A "smooth" hand cycling AR doesnt mean shit, Ive held plenty of perfectly reliable ARs that hand cycled roughly.

Wouldn't the "gas system" only contribute to function while the BCG is moving to the rear? All the video shows is that pressure on the bolt while moving forward will cause the cam pin to turn slightly causing binding. I just thought it was interesting.

[armatac]

Not this guy again, his "test is full of BS. The AR doesnt work like that. There's this thing called a gas system that provides the P-V work, not gravity or finger movement. Regular cam pins work fine, just replace them at regular intervals. A "smooth" hand cycling AR doesnt mean shit, Ive held plenty of perfectly reliable ARs that hand cycled roughly.

I can't tell what you are referring to,
(feeding)
If you are pushing on the bolt, and pushin on the back of the carrier,(which all AR types do) The cam pin is biased by the inside of the receiver to not allow the bolt to rotate. fact

This is a sliding friction, the part sliding is the lengthways stretch of the cam pin, Friction = coefficient of dynamic frictionXNormal load (normal load is a function of main spring, and cam path),
If you had a pure roller, there isn't really a friction loss in relation to the force supplied by the main spring.

Bearing vs. Bushing

[Heavy Metal]

You want to measure if there is a diference? I will give you a test.

Take a Full auto and a cyclic timer. If the roller significantly lowers resistance, the cyclic should go up a bit.

[armatac]

pact might work,

in the end a simple test of taking a cam pin head, pushing and sliding it along anodized aluminum in the long (and thin)direction, versus a roller pin with the roller against the anodized aluminum is the comparison.

guns work, I mean I just think this is something that is a good "upgrade" as it reduces drag. Drag on a working firearm isn't an issue unless it is extremely fouled or something else is wrong. So if this does help the extremely fouled condition I think it is a good idea.

looking forward to seeing some video tests

[Heavy Metal]

No, I didn't say I was going to do the test. I just proposed it as a way to quantify it.

I have neither the timer or the class three to do it.

[Tokarev]

I can't tell what you are referring to,
(feeding)
If you are pushing on the bolt, and pushin on the back of the carrier,(which all AR types do) The cam pin is biased by the inside of the receiver to not allow the bolt to rotate. fact

This is a sliding friction, the part sliding is the lengthways stretch of the cam pin, Friction = coefficient of dynamic frictionXNormal load (normal load is a function of main spring, and cam path),
If you had a pure roller, there isn't really a friction loss in relation to the force supplied by the main spring.

Bearing vs. Bushing

Would not the "push" portion that jams the cam pin against the left receiver wall be just for a split second while the bolt interacts with the top round in the magazine? Once the round is stripped from the mag and no longer held by the feed lips, I'd think the force against the bolt and cam pin would be gone. Or at least reduced dramatically. Once the bolt is almost closed and the extractor is being forced over the cartridge rim, the bolt is inside the barrel extension and acting against the extension and cam pin slot rather than the "slop" in the bolt carrier.

[armatac]

You are correct I think (in feeding), the largest force on the receiver from the cam pin would be from initial contact with the cartridge. It would continue to use small some force though until the cam pin actually reaches the cutout in the receiver to rotate, so the total possible drag length would be the distance from initial contact with cartridge in mag to the cutout in the receiver, which should correlate with the bolt head reaching the chamber face.

[Tokarev]

I'd also guess that intertia would have some affect on this. The bolt's high forward velocity would probably be pushing against the rear of the bolt, causing the cam pin to rotate in the cam pin groove slightly.