During this week’s NDIA Armaments Conference, Caleb McGee from Naval Surface Warfare Center – Crane conducted a briefing which detailed the test protocols used to evaluate the KeyMod and M-LOK weapon accessory attachment systems on behalf of the United States Special Operations Command. We recently published a FOIA released summary of that test which indicates that SOCOM selected M-LOK for use on the Suppressed Upper Reciever Group and Advanced Sniper Rifle programs. This briefing explains why they made that decision.

Crane procured Commercial-Off-The-Shelf rail systems which were offered in both KeyMod and M-LOK variants so as to offer direct comparisons. Modular rail systems were evaluated for repeatability, endurance, rough handling, drop testing, and static failure load.

The most remarkable differences between the two types of attachments was observed during repeatability testing. With variations measured in MOA, KeyMod exhibited a spread from 0.2 to 14.6 while M-LOK varied from 0.0 To 6.6 POA shift.

For the Endurance and Rough Handling tests, both KeyMod and M-LOK passed testing.

The imagery from the impact tests are shocking until you consider how the rails were tested.

Regardless, the results are clear.

In failure load testing which attempts to pull accessories from the rail from 90 Deg off-axis, Crane noted an increase of 215% in average sustained load of M-LOK over KeyMod.

Granted, the sample size of this testing is limited. However, for SOCOM, the conclusions were clear enough to choose a path forward. This test concludes that M-LOK is a more robust and more stable system. In addition to repeatedly maintaining point of aim for mounted accessories during normal mounting and remounting, it also better maintained rail intagrity in spite of impacts. On the other hand, testing shows that KeyMod suffered significant POA shifts during both repeated mounting and remounting as well as after impacts. Additionally, while both systems noted cracking under impact, some KeyMod rail samples lost integrity with fracturing beteeen slots.

One additional point to consider; Crane noted that it was extremely important to properly mount accessories to the rail. KeyMod did a much better job of self-aligning the accessory during mounting while M-LOK required more attention. The takeaway here is to pay attention while attaching accessories to the rail and to check zero after mounting.

For those interested, we have provided the entire briefing here. However, it will also be available on the NDIA proceedings section of the DTIC website in the next few weeks.