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Practically Shooting

AR "anti rotation" pins


Pablo

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I've got my Daniel Defense M4V3 all mechanically hooked up how I want it as I break it in. I added some more rail covers, installed a MAGPUL BAD lever, a nice Battle Arms Dev. (BAD!) ambi safety lever, and an excellent Raptor charging handle. The best thing is the gun is accurate beyond my wildest dreams.

Yet my work buddy and his magic smith are bugging me about these anti-rotation pins, which appear to be hammer and trigger pins locked together externally like this:

http://www.rainierarms.com/?page=shop/detail&product_id=325

How critical do you guys think these are? Will my DD receiver wear out prematurely without these?

On my buddies AR, they kinda stick up and bug me, but not hugely so.

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Not critical at all in my opinion.

I've never used them. I've never seen them on anyone's rifle in a class, student or instructor. I've never seen them in an active 3-gun shooter's rifle. I've never seen them in a high-use rifle.

Truthfully, as catty as it sounds, I've only seen them on rifles that don't get shot much but do get modified a lot.

There may be some aftermarket trigger systems that need them for some reason, but I don't see the need in a rifle with GI type internals.

I got my first AR in 1984. The disconnector was the first trigger part to wear enough to be replaced. Then the hammer. I changed the hammer spring twice as precautionary. The trigger pins still fit tight in their holes.

The upper and lower receiver stands up to a steel bolt carrier sliding back and forth, the hammer being slammed back to a cocked position which puts the load on the pivot pin and therefore the receiver pin hole, a charging handle latch snapping over it's ledge, each and ever cartridge being driven into and up the extended feedramp of an M4 lower, magazines (a lot of them aluminum or steel) in and out and the magwell, plus bears the stress of the stick, pistol grip, and oftentimes a rail mounted directly to the receiver and all the stress and forces coming from that.

I think it can handle a little rotation of the pins, which I think is minimal anyway unless they get taken out a lot and loosened up.

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Yeah, polymer. Maybe.

I doubt many of those see very heavy use, so I don't know how necessary that would be even there.

I kept thinking about this question at various times today.

I also keep thinking about all the M16s I've seen pictures of in distant lands that were worn shiny silver but their pins weren't falling out from wear. Then I thought- Just because they have worn exteriors doesn't mean they were shot a lot.

So then I thought about the ones I've seen at the Knob Creek MG Shoot getting more rounds through them in one weekend than 99% of ARs get in their lifetimes. I know of one that hit the quarter million mark a long time ago (several calibers besides 5.56), and is still in use as far as I know- And it didn't have locking pins.

I just don't think it's a problem. I know there are two concerns- that the pins will fall out, and that they will "waller out" the holes. I just don't think either is likely. Or probable.

They can't fall out if the fire control springs are in right, because the springs have legs to engage the grooves in the pins to retain them.

The holes could get beat out of round, I suppose, but I don't know what it would take. One would spend a lot more on barrels getting to that point than what a receiver would cost.

Like I said above, I'd say there was at least as much stress in other areas of the receiver halves, and that doesn't seem to be a concern.

I don't think I've ever seen or even heard of an AR/M16 receiver that was "worn out" unless maybe, just maybe, it was done on purpose.

Even when people thought they were doing a good thing and using chrome (exterior) bolt carriers, so they had an even harder surface running within the receiver, I don't know if they wore any out. The Army Marksmanship Unit was silver soldering pads to the rear end of the carrier so it wouldn't have any play within the receiver, but that was done to feel good. I think they said from the start it didn't help accuracy or durability. I don't think they've done it for a while.

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