Rings Too Tight?

[Vegas]

I came here expecting a treatise on torque specs for scope rings. I am bitterly disappointed. I am beginning to think the "low post quality" thread may be on to something.

[MistWolf]

This video from ARFcom will help tie this whole thread together

[arptsprt]

Finally... someone threw the softball... Lulz...

About 20 seconds into the video I was like, WTF? Really?

Paging Mr. Wells, Mr. Wells... your War of the Worlds is calling.



Sent from my iPhone using Tapatalk

[Circle_10]

I came here expecting a treatise on torque specs for scope rings. I am bitterly disappointed. I am beginning to think the "low post quality" thread may be on to something.

Actually scope ring torque values are an important factor in a total AR reliability package. And it is one of the reasons that optically sighted ARs tend to be less reliable than iron sighted ARs. As it turns out this is not due to the commonly held belief that scopes induce malfunctions but rather from their improperly deployed ancillary hardware. Over torqued rings can apply excess PSI on the top rail, which can result in concurrent separation of the upper receiver's distal margins. This can lead to something called Defrictioned Acceleratory Intensification, commonly called "float bolting". It is exactly what it sounds like. The receiver, being spread apart due to the pressures of high-torque rings, imparts decreased drag onto the carrier during the operational cycle. This allows the speed of the cycling carrier to increase at a geometric rate during the op stroke. While the most normal results are chronic failures to feed, or failures to lock open on the last round due to the extra-sonic cycling speeds of the Defrictioned BCG outrunning the mag flanges, in extreme cases the accelerating bolt carrier can blow the receiver extension straight out of the gun, turning it into a lethal projectile. The original Mk12 SPRs were particularly prone to this.
Although tight optics were the DOD standard per all known technical publications, and no deviation from these operational parameters were permitted, there was a workaround.
The forward assist, originally conceived as a way of assisting the weapon's bolt to stay closed during jungle HALO parachute landings, could also be used as an effective "bolt brake" during firing.
By maintaining firm, consistent pressure on the forward assist *during* firing, the ratchet spine of the assist engages the carrier scallop cuts and effectively slows the bolt carrier's travel down to within an optimal velocity curve, thus counteracting any potential effects of Defrictioned Acceleratory Intensification caused by overtorqued rings.
Now, this preventative measure can become difficult for a lone operator to perform while trying to engage targets in the field due to the ergonomic requirements of depressing the forward assist while shooting. So it became SOP to deploy a Designated Forward Assistor (often called a "bolt buddy" or "Fister" for short) along with every Mk12 shooter. The DFA's role would be to maintain the firm, consistent pressure on the forward assist required for optimal BCG cycling speeds while the shooter focuses on neutralizing targets. Due to the necessity of concealment in the field, the positions that would have to assumed by the DFA would often need to be of a parallel orientation to the shooter (the so called "double decker" method) and so could be considered a breach of personal space, so both the shooter and his bolt buddy would generally need to learn to get past whatever hangups they had about sustained close physical contact with one another.

[ChattanoogaPhil]

Many of these issues related to rings can be avoided with quality parts. I use Rockwell bolt, scope and delta rings.

https://www.youtube.com/watch?v=RXJKdh1KZ0w

[flenna]

Many of these issues related to rings can be avoided with quality parts. I use Rockwell bolt, scope and delta rings.

https://www.youtube.com/watch?v=RXJKdh1KZ0w

This still won’t overcome Defrictioned Acceleratory Intensification as mentioned above by Circle 10.

[AKDoug]

Many of these issues related to rings can be avoided with quality parts. I use Rockwell bolt, scope and delta rings.

https://www.youtube.com/watch?v=RXJKdh1KZ0w

You ain't shit unless you got in the group buy for the Rockwell stripped lowers.. but yeah, their rings are pretty good.

[Vegas]

Hmm, DFA? The more you know eh? This thread needs to be stickied, can't let this kind of knowledge slip away....