HKPRO Forums banner

MR223 flash hider

2.6K views 22 replies 12 participants last post by  SteelonTarget29  
#1 ·
Good day all. Fortunate to find an unfired MR223 in the US. Can anyone tell me if the MR FH is NATO spec? I wanted to get a B&T Rotex suppressor and needed to know which QD attachment works with OEM FH? I have a dead air sandman but am hesitant to change FH to accommodate it. Would rather leave the MR unmolested as far as changing stuff. I sent my MR762 to HK usa to remove the FH but they said they cannot (or will not) work on a MR.
Thanks for any help. Apologies for newbie question but could not find answer.
 
#4 ·
Thanks very much for your help. Is the MR FH difficult to remove? I know on the MR762 people were damaging their barrels because the FH was so tight. HK USA took mine off for free (minus shipping) because they knew the problem existed.
If they are relatively easy to remove, would a Dead Air Key MO 15X1 work or should I stick with HK FH?
Thanks again.
 
#5 ·
I do not know how difficult the FH is to remove, but if you do try make sure to use an appropriate reaction rod and vise. HK sells one, but they are very expensive and difficult to source. Nefarious Arms makes a reproduction and Haus may be another resource for the appropriate HK-style reaction rod. I have seen members on here loaning or renting the tool in the past.

As for attaching to the OEM FH one option may be an older Gemtech Halo that clamps behind the FH. Alignment issues may arise if the MR FH is not machined perpendicular to the bore. I am unaware of any other qd attachments that would work with the OEM MR223 FH.

Unfortunately, I think the best route is to change the flashhider. Contact Nefarious Arms if you are uncertain about the procedure. Hope this helps.
 
#6 ·
I removed the factory flash hiders off of my MR762 and one of my MR556's this past summer. All I did was soak the muzzle device in warm water for an hour or so and then put the barrel in a barrel vise and they both came right off with a good smack on the end of the wrench with a 5 pound rubber mallet. The Rocksett is water soluble and just needs a little time to dissolve. I cleaned the threads up with a dremel that had a brass bristle wheel on it and the MR556 got a Surefire 3 Prong on it and the MR762 got a B&T A2 NATO adapter on it. The B&T Surefire adapters work great on the Surefire muzzle devices and the B&T NATO A2 adapter locks up nice and tight on the NATO A2 flash hider. Both of the adapters I installed on my MR's got a small drop of Rocksett on the threads prior to installing the muzzle devices and then I let them sit undisturbed for 48 hours.

This is the barrel vise I used on both barrels. -> https://www.amazon.com/Mechforce-Professional-Barrel-Surface-Protection/dp/B01HU4GNSG

Rocksett -> Amazon.com
 
  • Like
Reactions: veritas
#9 ·
Does HK USA use thread locker on the MR flash hiders? I also can't speak for MR223s and MR308s in Europe, but I don't know why they'd bother with the thread locker due to the flash hiders not being timed or such aside from the flash hider backing off the threads.

I know that for normal HK mil-spec rifles they just torque the flash hiders down with no thread locker. On the G3 and G36 the usually also have a spring that engages with splines on the barrels to keep them from loosening. Newer rifles (HK416/417, 433/437) just torque them down with no retaining spring. A mil-spec exception is the M27/M38 USMC rifles, which use a timed M16A2/M4/AR-15A2 timed flash hider, I assume with a crush washer like on most rifles that use an A2 flash hider.

Also, "NATO" flash hider refers basically to any flash hider or muzzle brake that's 22mm diameter. This is an (IMO obsolete) requirement to use rifle grenades and mount bayonets. Bayonets, of course, are more often used as utility knives or fighting knives, and of NATO countries, only France still commonly uses rifle grenades.
 
#11 ·
Does HK USA use thread locker on the MR flash hiders? I also can't speak for MR223s and MR308s in Europe, but I don't know why they'd bother with the thread locker due to the flash hiders not being timed or such aside from the flash hider backing off the threads.

I know that for normal HK mil-spec rifles they just torque the flash hiders down with no thread locker. On the G3 and G36 the usually also have a spring that engages with splines on the barrels to keep them from loosening. Newer rifles (HK416/417, 433/437) just torque them down with no retaining spring. A mil-spec exception is the M27/M38 USMC rifles, which use a timed M16A2/M4/AR-15A2 timed flash hider, I assume with a crush washer like on most rifles that use an A2 flash hider.

Also, "NATO" flash hider refers basically to any flash hider or muzzle brake that's 22mm diameter. This is an (IMO obsolete) requirement to use rifle grenades and mount bayonets. Bayonets, of course, are more often used as utility knives or fighting knives, and of NATO countries, only France still commonly uses rifle grenades.
Are you sure about the crush washer on the M27? I've always thought that they are No, No with a suppressor.
 
#20 ·
Standard HK muzzle threads are metric 15x1 right hand thread. Only exceptions are maybe the HK416s that use HK's A1 birdcage (which might be 1/2x28), though the normal HK birdcage, open tine or A1 birdcage don't need timed (hence no need for shims or a crush washer, or a jam/lock nut). However, other flash hiders (A2 birdcage), let alone muzzle brakes or compensators will need timed.

HK MR223s and MR308s at least in Europe have the standard HK 15x1 threads, and use standard HK muzzle devices. Same applies to the HK243, be it with the G36 birdcage or G28 flash hider, as those are also 15x1 threads and are simply torqued down. The G28 flash hider is also on, of course, the G28Z and seems to be an option for the upcoming commercial MR223/308 A4/5/6 variants.
 
#21 ·