It’s unusual for the MOD to undertake such requests, or to have access to the material. Was it the SASC you contacted? Although part of the MOD, they are more likely to be helpful than higher level direct MOD.

The need for the extra ratchet locking mechanism is simple. The original locking mechanism is adequate for the standard shroud and barrel but was to feeble for the extra dimensions and weight of the suppressor. The increased surface area of the additional ratchet made for a much more secure attachment.