Free floated barrel = POI shift?

[5.56 Bonded SP]

The only way I'd expect absolutely no change in POI is if the handguard were attached to the upper receiver.

Like this?

https://aeroprecisionusa.com/ap/enha...pper-receiver/

[grizzman]

Yes. The rail attachment point is the same aluminum structure that the barrel nut screws into, so I don't consider it the ideal solution. It does seems substantial enough in size to reduce flex.

Mega's Megalithic upper is another example. It has an upper that's fully integrated with the handguards, and uses a very long barrel nut wrench for barrel attachment.

[AndyLate]

Sorry, thread drift, so I deleted.

Andy

[LMT/556]

Thinking back I don't think mine was .5mil, maybe closer to .3 but definitely enough to notice. I looked for the target but don't think I wrote anything down on it that day, probably in a hurry losing light...

[grizzman]

If a person shot the rifle at the bench with minimal contact, either with a bipod or bag....then tightened a sling at 90 degrees (again with minimal rifle contact) with roughly the same force as is applied to load the bipod from prone, I'd be curious to see if the POI shifted in the direction of sling pressure.

My guess is that it won't to a measurable degree, and that any POI shift from position to position is attributable to recoil differences instead of handguard pressure.

[grizzlyblake]

Curious - how much worse is a standard FSP barrel with two-piece handguards in the same situations? How much better in reality does the standard free-float tube perform in comparison?

[17K]

Early this year I tested that with a Colt SOCOM upper and KAC RAS hand guard. I didn't use a bipod, but prone on the mag, to rested on the rail, to tight sling showed a consistent 2 MOA shift between positions.

[crosseyedshooter]

Are you preloading the bipod differently than on bags? I think I automatically preload more when using a bipod.

[opngrnd]

I'll note that if you go to most of the Army's marksmanship competitions you'll see the better shooters do the magwell grip most of the time with their support hand, and virtually all the time in kneeling and prone. Their philosophy is that you'll always have a 30 round magazine, but you won't always have a bag/rest for your handguard, and there is a definite POI shift between the two, so use the magwell and monopod it all the time for precision shooting. Whether or not your Barrel is free-floating I'd bet that if you switch between a few different positions while doing 10 shot groups you definitely notice a shift in POI. Same for bags vs bipod, etc...

[grizzlyblake]

What about when using iron sights mounted to the rail in comparison to a barrel-mounted FSP?