Free Float Question I Haven't Seen Posted Yet

[R6436]

I have spent the past week looking for information and have been unable to find what I'm looking for. I apologize if this topic was asked prior and my search skills are just not on par to have found it. I also apologize if this was the wrong area of the forums to post, at this point I am at a loss as far as if this would be "Ar General Discussion" or "AR Technical Discussion". Having said all that, here is my question:

Which type of free float rail barrel nut attachment provides the strongest structural integrity?

From what I've seen, some the most referenced brands on here are BCM, MI, and Geissele. The three seem to have similar mounting with a barrel nut that does not require (or requires minimal) indexing, 1-2 cross bolts to secure the rail to the barrel nut, and depending on make/model possibly a bracket to prevent rotation. How do these compare to the strength of the old Delta ring assembly (stronger, more/less secure)? A less popular option I've seen is the Aero Precision M4E1 where the rail collar is actually part of the receiver and holds the hand guard in place with 8 screws. Is this system weaker than the BCM/MI/Geissele or is there a different reason for its lack of popularity?

I'm trying to part an idea for an upper that would have the least amount of potential failure points as possible while providing the strongest structural integrity. I'm open to suggestions and I am NOT looking for confirmation bias. I'm here to learn.

Thank you in advance!

[hk_shootr]

Interesting question.

I don’t believe any of the top brands would have a failure point. You would have to beat the piss out of a rifle to get any of the quality rails to fail. Personally, I prefer Knights URX series, I feel they are the strongest design I’ve seen.

[R6436]

Interesting question.

I don’t believe any of the top brands would have a failure point. You would have to beat the piss out of a rifle to get any of the quality rails to fail. Personally, I prefer Knights URX series, I feel they are the strongest design I’ve seen.

It's been a conundrum for me this past week. I see manufacturers listing maybe a line or two about how they are the best choice, but never really why their design is better than others. Plus there's quite the similarity between most of them... yet again not really a "why" for the barrel nut design they use. Is it a trend? Common supplier?

I looked into the KAC URX due to your suggestion. If they had an offering that was compatible with a mid length with FSB they would be on top of my "buy" list for this project. Definitely on my list for the next project tho, so "thank you"!

[dmd08]

I've never seen the MI barrel nut listed as one of the best.

I haven't used a BCM rail yet but would have no problem doing so. I like that they clamp at the top of the barrel nut. I think this makes perfect sense.

I'm am a big fan of the Geissele barrel nut. I'll add ALG barrel nuts also since they are similar. I've used them both and they impress me.

I think the m4e1 system could possibly be the strongest but I don't want to be married to that upper and that rail forever. And that's why I think it's not popular. Also Aero doesn't have the same name recognition in rails as Geissele or BCM so some brand bias is probably part of it also.

[R6436]

I've never seen the MI barrel nut listed as one of the best.

I haven't used a BCM rail yet but would have no problem doing so. I like that they clamp at the top of the barrel nut. I think this makes perfect sense.

I'm am a big fan of the Geissele barrel nut. I'll add ALG barrel nuts also since they are similar. I've used them both and they impress me.

I think the m4e1 system could possibly be the strongest but I don't want to be married to that upper and that rail forever. And that's why I think it's not popular. Also Aero doesn't have the same name recognition in rails as Geissele or BCM so some brand bias is probably part of it also.

Not trying to be argumentative, because your response is actually helpful. That being said, could you please try to explain why the BCM clamp on top makes sense to you? I'm genuinely curious.

As for the AP system, I have access to one of the M4E1 uppers but I also have multiple regular/threaded uppers. I do recognize going with one of the AP's does limit options to only 2-3 manufacturers for rails, and that number is steadily shrinking.

I should probably note that the current plan for this upper includes having an FSB instead of a low profile gas block.

[dmd08]

Not trying to be argumentative, because your response is actually helpful. That being said, could you please try to explain why the BCM clamp on top makes sense to you? I'm genuinely curious.

First off I am not an engineer.

The rail is not a complete circle of metal around the barrel nut since you have to have the channel at 12 o'clock for the gas tube/gas block to fit through. Clamping the rail at the bottom of the barrel nut seems like it could create flex in the channel at 12 o'clock. Clamping the rail at the top of the barrel nut cinches the rail around the barrel nut with no room for any flex or expansion. Whether this is actually happening or if it even matters if it's happening is for you to decide. As I said I haven't used a BCM rail yet. And the Geissele rails I do have clamp at the bottom. With a good design it probably doesn't matter but when I see how BCM does it, it just makes sense to me.

I made an ugly paint picture to show what I'm thinking.
Attachment 50977

[officerX]

An uneducated guess would be the one with the most surface area, like the standard barrel nut, and those rails that use it as their mounting point. One that immediately comes to mind is the Fortis REV rail.

[Biggy]

The only handguards I will put on my personal rifles are Geissele or the Hodge/ Mega wedge lock. They are both strong and easily removed if need be without special tools. IMHO, durability trumps lightweight if I have to sacrifice any durability to get it. IMHO, the longer barrel nuts of these two handguards are an important part of the equation. IMHO, currently I believe the *overall* best handguard you cannot get *yet* is the Geissele MK16. The slightly larger I.D. of the MK16 is a little more user friendly with gasblock size and it has M-LOK slots at the 10& 2:00 o'clock location compared to the Hodge/Mega handguards. The Hodge/Mega handguards use the superior and stronger 7075 T6 aluminum alloy. I think the weight of these two are about a toss up, but the weight of the Geissele *might* be 1-2 oz's lighter.

[R6436]

The only handguards I will put on my personal rifles are Geissele or the Hodge/ Mega wedge lock. They are both strong and easily removed if need be without special tools. IMHO, durability trumps lightweight if I have to sacrifice any durability to get it. IMHO, the longer barrel nuts of these two handguards are an important part of the equation. IMHO, currently I believe the *overall* best handguard you cannot get *yet* is the Geissele MK16. The slightly larger I.D. of the MK16 is a little more user friendly with gasblock size and it has M-LOK slots at the 10& 2:00 o'clock location compared to the Hodge/Mega handguards. The Hodge/Mega handguards use the superior and stronger 7075 T6 aluminum alloy. I think the weight of these two are about a toss up, but the weight of the Geissele *might* be 1-2 oz's lighter.

Non-proprietary tools is definitely a plus, same with longer barrel nuts. If you don't mind my asking, how does the Hodge/Mega anti-rotation system work? I see on Mega's site it is a pin, is this in the absence of tabs on the top near the rail?

[Biggy]

Non-proprietary tools is definitely a plus, same with longer barrel nuts. If you don't mind my asking, how does the Hodge/Mega anti-rotation system work? I see on Mega's site it is a pin, is this in the absence of tabs on the top near the rail?

Yes, the pin from the handguard going into the upper is the main anti-rotation device on the MEGA/Hodge handguards, so you would need to use an upper that is compatable with them (Hodge, Mega and there are others forged and billet ones out there). They also incorporate two small set screws that go through the handguard and bear against the barrel nut, one on each side that would help a little. I like to torque barrel my barrel nuts to 45-50 ft lbs. Also, the barrel nut to handguard fit on the Geissele and Mega handguards is usually very snug and *do not* not distort the upper rail at all when they are tightened or fastened on. You may see some rail distortion when tightening some handguards on, when using some of the cheaper and what I like to call the squish type clamp on handguards