[HongKongCavalier]

I've had my PTR-91F for about 7 years, used to be on these forums quite a bit.

I recently decided to mount a Hi-Lux CMR 1-4x, and the only way it seemed "right" was on medium rings, which made removing the rear drum necessary. The old scope was taller and I used one of those plastic cheekrests that plug into the buttstock holes. It just didn't seem to work as well with this new scope, seemed awkward.

Does anyone make a low profile flip-up style rear sight for the 91?

Also, any real tried-and-true recoil reduction? Sometimes I shoot a friend's 16" AR-10 with a muzzle brake and am downright jealous, barely any felt recoil. I really don't want to leave the PTR behind as I love nearly everything else about the platform.

 

[NuJudge]

This is probably not what you are thinking about in the way of flip-up sights, but the CETME rear sight is a flip-up.

There are aftermarket compensators for the HK91/PTR. I have used one for awhile with My PTR91. My PTR is muzzle threaded the same as a HK91. The one I have is:
https://www.hkparts.net/shop/pc/PWS-FSC-HK-Threaded-Barrel-Compensator-15X1-RH-121p837.htm

The biggest problems with a compensator can be increased flash and blast. I don't see significantly increased flash or blast with the PWS compensator. I do note some reduction in recoil with the PWS compensator, but I don't mind the recoil with the factory flash hider.

I have a reproduction FG42, which has a much more efficient flash hider. Recoil with 198gr 8x57 ammunition is about the same as an SKS in 7.62x39. Not every shot, but about every 5 or 10 shots the muzzle flash is truly impressive. Muzzle blast is impressive with every shot: I put a 7-11 Big Gulp on the bench near the muzzle, and the muzzle blast blew it off the bench.