.338 Whisper #2 in HK91 platform?

[THE DOCTOR]

in theory it should be simple but getting a fluted chamber like the 93 for a 338 will likely be difficult and achieving enough pressure to unlock the rollers will be a big hill to climb. trimming the mainspring can only go so far because it will not want to rechamber a new round just like the ar

i am running a wolff lightened spring on my ar and it works great

You might get wolff to make you a custom spring nice guy there would be worth a try

again I wish you lots of luck