Not SCAR hating but I can confirm that it sure wiggles scopes and other accessories a bit.

My experience is that I bought mines with 6 magazines for 2k and I sold it to my brother afterwards.

The muzzle brake and the recommendation to go to a geiselle trigger was the park that angered me the most.


I will get back to the SCAR someday but not today.

Asked and waiting for an answer.  

You are awesome! Thanks for posting this!

 

I bought a surplus Zeiss Orion night scope a while back and intended to sight it in on my SCAR 17.  Should I expect the orion to fall apart?

Answered.

A couple possibilities that could explain why a SCAR-17 might be more prone to eating scopes than other comparable rifles.  As has been mentioned already, there could be a qualitatively different recoil impulse--more forward slam, faster and more intense rearward impulse, etc.  SCARs are unique rifles compared to what came before in that the mass of the BCG is a much higher percentage of overall weight, thanks to the light upper and lower.  The same amount of momentum in a SCAR's BCG will produce more shock to the rifle and its attachments than the exact same amount of BCG momentum in a rifle with more massive steel upper and lower.  Again, the recoil in question could be different in ways not detectable to the human nervous system.

Another possibility is flex.  SCAR uppers are extruded aluminum and the lowers are plastic, both of which are more wiggly than a milled aluminum or steel forging.  SCAR recoil could bend the scope in ways that aren't experienced on other rifles, or the rifle could flex and then spring back to normal in a manner that exacerbates recoil impulses.

Nothing short of painstaking analysis with a high-speed camera will settle the issue of flex, but attaching an accelerometer to some rifles and shooting them could answer the question of different recoil forces.  I've found an Android app that collects data from a phone's accelerometer, so I'll duct tape that sucker to a rifle when I get the chance and see if it's accurate enough to illuminate any differences.

Edit: This app won't work.  Its maximum resolution uses a time slice of 0.06 seconds, which is far too large an interval.  Anyone know of any cheap high-resolution accelerometers?

I'll be building an accelerometer sometime in the future. I'll throw it on my SCAR 16 when it is finished. I'm pretty busy so it won't be for at least a few months.

New SCAR 17, ordered a SWFA SS 3-15x42 mil/mil scope.  The SWFA SS line of scopes is highly regarded and is ok'd for 50 cal use..within 10 shots the paralax knob fell off.  I'm sure it's coincidence, but I must admit that I'm wondering...

Good point.

A federal agency looking at Glocks a couple years back did some high-speed film of them and watched the frames flex a lot under fire.  It went a ways to explain failures of weapon lights on polymer pistols that were being experienced.  The flex of the pistol wasn't something that had been looked at much before then.

The same could be a contributing factor for rifles.

The only slow-mo SCAR firing I could find online isn't anything that's precise enough to give much insight.

If they are designed for the SCAR-17, why do they have .223 reticles?

TA11H: Trijicon ACOG 3.5x35 Scope, Dual Illuminated Red Horseshoe .223 Ballistic Reticle w/ TA51 Mount

TA11J: Trijicon ACOG 3.5x35 Scope, Dual Illuminated Red Crosshair .223 Ballistic Reticle w/ TA51 Mount

Both are offered in .308 calibration:
http://www.trijicon.com/na_en/products/product2.php?id=ACOG&mid=3.5%20x%2035

Thanks I just searched on TA11H, not TA11-H308, etc.

A little more edjumocation for ya...

If you look through an 3.5x ACOG it'll say (at the 6 o'clock position) which reticle / calibration it has.  My TA11-308-HG says "308" in this location. Otherwise, I don't know how you could tell them apart (no indication on the exterior).

Granted its a SCAR 16 but i have yet had a problem with my Aimpoint Comp M4.

Approximately 2K down the tube.



CAB

While shooting a Glock 20 you can feel the frame flex quite a bit if you pay attention. I have never noticed this in a G22 but don't doubt it does the same thing.

If SCAR rifles are hard on optics I would say this is an issue for the optics manufacturers to resolve. The SCAR design doesn't seem to be going away any time soon, even with the pricing like it is, and they work. Accessories will have to adapt eventually.

How about this,,,,

Please state if you have problems and then whether or not you are running the factory muzzle comp.

I just wonder if the problem is a combination of the heavy bolt carrier AND that noisy f^in break. I shot a scar17 and was surprised at the efficiency of the break. But taking it off really changed that feel.

if flex is an issue, then a scope mounted via two separate risers would be most susceptible to damage

How was the felt recoil without the brake?  Also, did it changed the direction of the impulse?

I don't think the muzzle brake is the issue, because the military Scar-H's have flash suppressors and there is internet chatter about .gov breaking optics on the Heavy.

I'd like to hear about what changing the brake does for the feel.  Every time I shoot my 17 I ended up with a headache as a result of that danged MB!

My first time shooting my 17 I had to use plugs and muffs which I thought absurd. Put an AAC Blackout on it and I'm fine with either or now. As far as impulse I can't really quantitatively say but it seems the duration of recoil impulse is shorter and a bit more harsh. Totally subjective and unscientific. I have a TA31 on mine in a LT mount.

Gary, I had the same problem with my 17. Just shooting off one magazine would cause my teeth to literally hurt. I put a .308 A2 FH on it soon afterward. Made all the difference in the world. Muzzle jump is a little more pronounced but definitely not so much as to cause me to take that A2 off and go back to the PWS... I have about 1300 rounds of surplus through my 17 now with a Leupy VX-R Patrol optic/LaRue mount. No problems whatsoever.

Oh come on brother, apples and oranges.
The Aimpoint is bulletproof, and the Scar16 has light recoil.

anyways, this has got me curious. I've got an Elcan 1.5-6 on mine, pre HD. I hope I'm good. but I may be in the market for a more suitable optic, perhaps a 1-8 USO?

I had a SWFA SS 1-6x mounted in a Bobro standard mount on my 17.  After about 100 rounds the illumination dial failed and was beginning to pull away from the scope body.  SWFA replaced the scope under warranty.  I had the Bobro running backwards to keep the lever on the opposite side of my charging handle.  I'm not sure if having the "diving board" to the rear was a contributing factor to the scope failure or not.

I have since sold the mount and scope.  I'm going to be running a ADM mount without any cantilever.   That, combined with a SWFA SS 3-9xthat has no Iillumination or parallax adjustment may make for a more robust combination.

Thanks for the info.  I've been thinking about going to traditional FH's on my Scars.  How did you remove the PWS? Barrel blocks?

Yup blocks of hard wood scoop out a bit of each block to form a shallow channel but not as deep as the barrel is wide you need a gap or no clamping force. degrease the section your going to clamp. Rosin helps to keep it from slipping but not necessary.  Helps to remove the barrel from the reciever but not neccessary.  

One wrench on nut one on the brake and twist.  

You can remove it just with it laying on a table but you don't have much control and need three hands.

I've replaced mine with a surefire hider since I run suppressed.  I may put the brake back on since its only bad under cover or indoors.

Thanks.  I might try a FH on the 17.

Haven't read every page, but does anyone know how an aimpoint pro holds up on a 17s?

Talked to TNVC today.  Said the OTAL along with their other lazers will hold up. Guy said he runs the 17 just fine.  Also stated that his US optics and some other scope work fine to.

I didn't need a vice at all.

 

Use 2 wrench's, one on the flashider, the second on the jam nut.  Pull the flashider wrench towards you to loosen it from the jam nut.  The wrench on the jam nut is just to stabilize it from the loosening of the flashider.

Yep, one on the jamb nut and the other on the brake. If you're just using a flash hider and not going to mount a suppressor, you can reuse the jamb nut. If you plan on a suppressor, you can just tighten the flash hider till it bottoms out on the muzzle but then use barrel blocks for proper torque.

 

I've put over 4K through my 16 with an Aimpoint COMP M4 and i have had zero issues.

 

Light weight with a high impulse cartridge will be hard on optics or electronics. Adding a muzzle brake that induces negative G forces only makes it worse.

The Leupold MK4 was one of the 1st optics that survived the recoil of the .50 bmg on rifles running effective brakes. The G force recoil curve had a sharp peak then dropped to negative G's once the gas hit the muzzle brake. Scopes / optics at the time were never designed to handle recoil forces in opposite directions.

Primary Arms Micro T-1 clone on SCAR-17 holding up well with over 1k rounds down range. Threw this on there as a gag/test and have been astoundingly impressed. I figured I'd use it until it fails. Hasn't failed/lost zero yet. Using AD quick detach mount.
I really think it's mostly the MIL full auto crowd that is having most of the problems. I used a TA31F on my first SCAR17 and had about 4k rounds through it without issue before selling it after Sandy Hook.

So,

I have recently come back from my last little bit of military tourism. Before I left I did some consulting for one company that did take a really good long look at this issue, Handl Defense.

They have guys from the aerospace and military aircraft industry that work for them (guys from the F-22/F-35 and civ air). They looked at the recoil impulse and gas flow dynamics of the Mk.17. This was done in anticipation of the conversion caliber kits (7.62x39 and 300blk) of the Handl Defense Mk.17/ Mk. 20 improvement program.

They found that recoil impulse on both ends of the BCG stroke, fore and aft was much different than any other 308 rifle they had. I do not remember the particulars but the end result was a few new products. Gas Control screws were one (the FN ones corrode prematurely) and the butt-stock base plate was another.

They have a re designed civilian butt-stock base plate available now. But for the military version (MOD 2) they changed the design again to compensate for full auto fire.

I have shot the Handl demo model, it has a completely different feel to its recoil. follow on shots are much easier.

Earlier in this thread I said my acog ta33 has been fine for over 1000 rounds.

it went tits up this weekend.

the factory mount had loosened to finger tight. the optic held zero but the connection between the reticle and the fiber optic is out the reticule no longer glows or has any color.

SO HERE IS A  FIRST PERSON ACCURATE ACCOUNT OF A SCAR 17 BREAKING AN TA33 ACOG AT AROUND 1600 ROUNDS.  

Well, this just sucks.  In the past month I spent a small fortune on top of the line ACOGs for my SCARs.  I made this decision largely based upon this thread and what Trijicon told me about the TA11-H 308 being designed for the 17.

I will say that having owned over a dozen ACOGs the TA33 seemed to be the least durable (based upon the appearance of having the part screwed on the front).  I sold mine quickly.

Anyway, please let us know what Trijicon says.

Was it this thread or another where somone mentioned Handl defence actually doing the testing I and others mentioned needing to be done, and showing the hypothesis true that the SCAR-17 has a crazy recoil impulse?

Do you mean the post 3 posts before yours? Or was their a different one with more info?

Can I make up for looking like an idiot by saying it was another post.



 

LOL

I use a Vortex Viper PST 2.5 10x32 . Runs just fine. If it dies they'll
Fix it. No worries. Shoot-die-repeat.

So I do not normally post up much, but this I think needs explored. I called Alan Handl and asked him about what I can share openly. They had some real bad experiences with competitors rev-engineering their stuff (that is the FBI talking not me BTW) so they do not like coming forward with the 5 W's. They have one dedicated guy to insure trade secrets from the Mk.17 / Mk. 20 improvement program do not get out, as in FN wants to know.

I was the lead military consultant for Handl Defense in relation to the needs/desires of USSOCOM (Spec sheet/user feed back etc.)  a little while after they came out with their 1st revision SR-25 lower. They did a full analysis of the lower, upper, and all internals. First it was measurements, the FN lower was found to be serious sloppy. I have seen ones come off of MK.17's that would wobble like a chair with a short leg they were so warped, don't even get me started on buttstocks.  Second, after they brought everything back in house (the first 300 lowers were farmed out) they started to look at Gas Flow dynamics of the operating system (needed for the caliber conversions USSOCOM requires and other stuff), recoil impulse, tensile strength, and more importantly compressive strength. (I watched first hand the abuse of scars that I considered blasphemous)

You might ask WTF why? well most of the guys who work the machines that produce Handl Defense parts, make parts for the F-22/F-35 and 787 etc. They have an understanding of the stresses materials go through at a Phd level, which is a requirement of the aerospace industry. But for some of the guys in the shop this is their first real foray into firearms. They need to know the why, what does what. Which leads to the core of the conversation.

Recoil Impulse and Compressive strength

Three specific parts on the SCAR-H / Mk.17/ 17S exacerbate problems throughout the gun. Handl Defense discovered this in about Jan of 2012, but really had it dialed in by say MAY. Due to the cost of taking some of this stuff to the civilian market is too high for such a small market. The DOD procurement of the Handl Defense MK.17 / Mk.20 program will eventual cause these parts and kit to be released to the civilian population (there are some already out)

So just know the answers have been found, the CAD drawings are done, the prototypes are on the shelves, waiting on DOD $ for full production. I  have shot the test bed with all the parts on it, the recoil is subdued, feels about like say 65-70% of normal, serious improvement for follow on shots.  I have to be sort of cryptic (DoD dir 5210 and all) but things are looking up for the whole program. I know Handl is meeting with NSWC Crane reps on Thursday.

The Optics issue came up when Handl did a 1000 round test.  20 XS 50 round drums back to back (notice XS drums runs Handl lowers). They broke two optics then went to just irons on the gun.

What was found, was the FA fire caused reverberation of recoil impulse throughout the gun that caused unique stresses. Exacerbated by stock parts that were designed when the Mk.16 was the focus of the program, among other issues. The pattern of recoil fore and aft was very different than an AR, more like a machine gun similar in effect to a M240. I was standing right there when it was said to Alan Handl "this thing beats the shit out of itself". They think that there is one part of the gun that is designed to take all the damage, it is designed to be the weak point and take the impulse so that other parts do not fail before it. I would say this probably is a cumulative effect kind of thing the FA just made it stand out early.

I now know why many of the first few Mk.17's were having issues in and around the 2008  time frame. Handl Defense solved the issues, the problem with optics (which is real) is tied to other issues the gun has. Is the casual civilian owner of a semi only gun going to see them, most likely not. Many of the military users might not, but they are there. When you push the gun, they show up.

As for optics, as your self would I put this on a M204B? if you would say yes then slap it to your SCAR then you can sleep easy. But 95% of the time you are not going to have an issue in the non FA world.

BLUF: Shock testing was done in 2009 by .gov.   Accelerometers and shock simulators.  the whole nine yards.   Most optics are designed for reaward recoil.   The SCAR family has a nice forward recoil spike from the moving parts assembly (bolt carrier) striking the barrel extension.  This is what was causing the breaking.   Many $$ were spent on optic/laser redesign.   A safe bet is on any of the current optics you see the mil running (elcan, NF, Leupold and newer Trijicons).  But i do know the Elcan was hardened for the scar.

to the above two posters thank YOU stuff like the above post is why I hang OUT HERE.  

I think we have  SOLID ANSWER  NOW, AND I THINK I MAY HAVE JUST  BEEN SOLD ON A HANDEL LOWER.

This is perhaps the most intelligent page of posts I have read on ARfcom in over a year!

Helped a lot as I am looking to take the plunge into the SCAR Heavy world!  Thanks.