SCAR 17 "HARD" on optics?

[MBtech]

I have searched through quite a few threads and pretty much have came up with SCARs are "Hard" on optics for the most part.
I have also seen several comments on mount choice being a factor for optic survival on a SCAR.

Questions...

#1 Why are they "Hard" on optics?
What is it about the SCAR harmonics and the way it functions that give it this reputation?

#2 Have you had experience "Killing" an optic riding on top of it?
If so, what brand/model? What mount was it riding in? How many rounds?

#3 What is proven to withstand the perceived torture?

[Fox33]

#1 It has to do with recoil impulses and that they are VERY different than AR/M4 recoils. NSWC Crane put out an approved list for Mk.17 use. It wasn't only optics shitting the bed riding a Mk.17. Some people in other places are under the full impression the SCAR has no issues what so ever. They are mostly correct, but as the gun is pushed some things do develop. Most owners will never experience these issues IMO.

#2 I watched Handl Defense as they were doing their 5000 round test on a SCAR eat two Eotech 552's. If you ever see any of the test videos you'll notice no optics now.

#3 Look at what SOCOM runs, Elcans. Handl Defense says Elcan, Aimpoint, and US Optics. I say Leupold Mk.6 and Mk.8 CQBSS, Aimpoint T1, and Vortex HDII 1-6 (because of the no hassle return policy those companies have)

[snaggletooth]

I was wondering if the Schmidt and Bender Short Dot would qualify for #3? Or did that optic crap out?

[RyanB]

Peak G force on a SCAR16 is 4x that of an M4. I assume it's similar with 7.62. The cause of it apparently is the short stroke piston slapping the hell out of the carrier.

A guy at Group told me that they were breaking SCARs literally as fast as FN was sending them.

[1911-A1]

I have a 1-6 Super Sniper on my SCAR17, and I took it through a 400rd class plus various range sessions and haven't noticed anything, but I'll be keeping an eye on it as it passes 1000rds.

[Mikey421]

I thought the piston and carrier assemblies were connected the same as the FNC was. I had the impression that the SCAR was the FNC evolved. The 17 being 7.62 NATO does have a much higher recoil pulse than the M4, but the dual return spring/buffer assembly should mute that somewhat, wouldn't it Be?


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[nate89]

Holy profile pic Batman!

[Leaveammoforme]

Holy profile pic Batman!

I was going through the noggin archives trying to figure out who that was and how they pertained to a SCAR. After great pondering I realized it was a profile pic. LOLz.

[RyanB]

I thought the piston and carrier assemblies were connected the same as the FNC was. I had the impression that the SCAR was the FNC evolved. The 17 being 7.62 NATO does have a much higher recoil pulse than the M4, but the dual return spring/buffer assembly should mute that somewhat, wouldn't it Be?


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It's short stroke.

Felt recoil isn't the issue it's the acceleration of the gun.

[LRRPF52]

There's a great thread here where one of the members hooked his SCAR-16 and 11.5" AR15 SBR up to a G meter, and posted the readings.

On one hand, the SCAR's operating system ( a shameless copy of the AR18 via the G36 if you compare them ), uses a more elongated path for the cam pin, so that pressures can be reduced more before primary extraction occurs. H&K did their homework when they introduced this cam pin track to the AR18 bolt carrier. I think this is a good thing, however, does the flip side of that cause some of these harsher G forces seen in the SCAR? It would take some serious engineering analysis to find out. Here's the original Armalite AR-180 (notice the cam pin track):



SCAR-L next to H&K (again, look at the cam pin tracks now):



On the other hand, there is one solid reciprocating mass, whereas the Stoner DI system uses a series of masses that have a staged effect when cycling to the rear, as well as back into battery. The AR18 and AR16 also had different recoil spring arrangements that contributed to a significantly reduced height profile of the guns, whereas the SCAR and G36 have serious height above bore considerations.

This, and some other peripheral aspects of the gun ( buttstock mainly ) are what lead me to conclude for myself that the SCAR-L and SCAR-H are what should be prototypes that were rushed too fast into production. FN took some good designs and improvements from Stoner and H&K, but didn't fully evolve this thing to a point where it could have gone. If you look at the original Stoner designs, I think the secret lies there.

That said, I think there might be a market for major component assemblies of the gun, but they will need to be significant re-designs. I think the bolt geometry on the SCAR-L is what a 5.56 bolt should look like in terms of its size. Not so much on the SCAR-H, but they have addressed it with metallurgy I'm told.