Upper Receiver Handguard Anti Rotation Pin Hole - Worth it?

[Franko]

The handguard I want to use (Vseven) has an anti-rotation pin. The upper receiver I want to use (LMT Flat Top) does not. Is the anti-rotation pin important enough that I need to use another upper (FCD URF) with the hole or have a hole drilled into the LMT? Or is it ok to use the LMT upper/handguard combo as is without the pin?

Thanks.

 

[TheOE800]

The handguard I want to use (Vseven) has an anti-rotation pin. The upper receiver I want to use (LMT Flat Top) does not. Is the anti-rotation pin important enough that I need to use another upper (FCD URF) with the hole or have a hole drilled into the LMT? Or is it ok to use the LMT upper/handguard combo as is without the pin?

Thanks.

It has no secondary anti-rotation feature beyond the pin, correct? I would personally want to use an upper with the pin, whether that means getting it drilled on the LMT (which is a nice, but expensive TDP-spec upper with no real enhancements beyond good dry film) by a competent smith or getting another upper. SOLGW says you don’t need to use the pin, but that’s because their rails use that index pin as a secondary feature since they have the tabs around the upper to prevent obscene rotation as a primary feature.

In all likelihood you will be fine without the pin if the torque on installation is sufficient. For a hard-use rifle though…

 

[Franko]

It has no secondary anti-rotation feature beyond the pin, correct? I would personally want to use an upper with the pin, whether that means getting it drilled on the LMT (which is a nice, but expensive TDP-spec upper with no real enhancements beyond good dry film) by a competent smith or getting another upper. SOLGW says you don’t need to use the pin, but that’s because their rails use that index pin as a secondary feature since they have the tabs around the upper to prevent obscene rotation as a primary feature.

In all likelihood you will be fine without the pin if the torque on installation is sufficient. For a hard-use rifle though…

The Vseven uses their special barrel nut as the primary anti-rotation. The nut has a pair of attachment points at 3, 6, and 9 o'clock. 6 bolts then go through the handguard and attach to the nut. So the pin appears to be a secondary anti-rotation feature. But, I will take all the reliability I can get so I am leaning towards finding somebody to drill my upper as well.

I am leaning towards the LMT upper as I have a ambi LMT MARS-L lower and want to preserve all that functionality. I don't want to buy a different upper and find it doesn't work with the lower...

 

[TheOE800]

The Vseven uses their special barrel nut as the primary anti-rotation. The nut has a pair of attachment points at 3, 6, and 9 o'clock. 6 bolts then go through the handguard and attach to the nut. So the pin appears to be a secondary anti-rotation feature. But, I will take all the reliability I can get so I am leaning towards finding somebody to drill my upper as well.

I am leaning towards the LMT upper as I have a ambi LMT MARS-L lower and want to preserve all that functionality. I don't want to buy a different upper and find it doesn't work with the lower...

Any milspec upper will work, typically forgings though an enhanced design like the VLTOR won’t. Those billet URF uppers, if you like them, have a cutout in their deflector specifically for the MARS lever.

 

[bonifacio]

Do you need to? No.
But do you want to think about it all the time? Every time you look at it, you'll just think of the pin that's not there. It's additional comfort. Like when you wake up in bed and it's nice and warm. Comfortable. Not hot. Then you notice you peed the bed... Just kidding about the last part.

I threw together a nice at the time AR and had a Noveske NSR on it. The billet upper didn't have an anti-rotational pin hole. The barrel nut is torqued. Then the rail is secure to the barrel nut by I think 6 bolts. This would always keep the barrel nut and rail timed. If by some freak accident the barrel nut moved a little, it would then end up placing that pressure on the gas tube. The pin would and should prevent that. So it's like insurance for the highly unlikely to happen type situation. So... I ended up tearing it apart and redoing it. Just to fill that little pin hole.

 

[iktomi]

Nice to have. Provides confidence that there isn't drift with secondary aiming devices attached to the forend... I've definitely had issues in the past with handguards moving on me over time. Lessons were learned. Now, I try and find something to keep forend indexed.