I have found a method to get NATO STANAG filters working in a Soviet GOST thread, so NATO filters will fit a GP-5!
To do this you will need a 40mm rubber O-Ring, the O-Ring will create enough bulk in the thread housing of the GOST mask to allow a NATO filter to push against it making an air tight seal.
Remember by forcing a NATO filter onto a GOST mask you can still damage the thread.
Support me on Patreon
Please comment, rate and subscribe for more.
Follow me on Facebook and Twitter for updates: