Scar 20s muzzle device change

[ScarlettRed]

Hey guys,
A couple weeks ago I mentioned in a scar thread that my 6.5cm was piercing primers and blowing a few as well. This occurred suppressed and unsuppressed. Apparently it has been an issue with a few others. I tried to analyze the problem and then took it to mile high and get their advice as well but couldn't really figure what its main issue was. I sent it back to FN and got it back yesterday with a new barrel, bolt and firing pin but no explanation. I'm not sure I'm happy about it as it shot under 1/2 moa even while blowing primers. Anyway, tried heating it up to change the muzzle device and it ain't budging. It looks like a dimple underneath the brake has been added as a makeshift pinning attempt. Do any of you have this dimple in your 20's? I don't recall having it there on my previous barrel or my 308 20's.

 

[Kuhlen]

The brake that came on my 6.5 scar 20 has the same dimple. It was pretty tough to get off, just us a little heat and it will come.

 

[ScarlettRed]

Damn, I had mine practically glowing and it wasn't wanting to move. My previous 20s barrels were tough but this one, a little scary. On a good note, I took it out to shoot a few rounds to get on paper and finally got it on the bullseye with 4 rounds in 1/2". No primer issues. Bad note, my scope appears to be bottomed out with this new barrel and I had to aim 2.5 mils low to hit center. Apparently my scar no longer tolerates a 6moa scope mount.

 

[ScarlettRed]

I forgot to ask, does that dimple protrude through the brake in any way causing some of the friction we encounter?

 

[Kuhlen]

It doesn’t go all the way through, just a small blind hole

 

[Kuhlen]

Everyone I’ve seen in 6.5 shoots great, easily under 3/4” 5 shot groups.

 

[longshot2000]

Damn, I had mine practically glowing and it wasn't wanting to move. My previous 20s barrels were tough but this one, a little scary. On a good note, I took it out to shoot a few rounds to get on paper and finally got it on the bullseye with 4 rounds in 1/2". No primer issues. Bad note, my scope appears to be bottomed out with this new barrel and I had to aim 2.5 mils low to hit center. Apparently my scar no longer tolerates a 6moa scope mount.

We have sold a lot (I mean a lot) of 6.5 CM Scar 20s' and not seen any problems with the primers, but I have heard this before. My guess is it was a bat firing pin in a small number of rifles. Glad you got it fixed.

You should be expect 3/4 MOA give or take on that rifle. It is a sniper grade gas gun, but it is also a Scar. Scars have been know for more recoil and harder to hit repeat shots, but also give you some tactical advantages.

You mention you have a 6 MOA mount. What mount is that? That is an unusual number. Maybe a Spuhr. General rule of thumb is you want 1.50" height mount for a 56mm objective lens. I realize not all 56mm lenses are the same, but that is with 0 MOA. 6 MOA would cause a little closer to the rail, but I bet you are running 1.44" or something like that. This is not he rifle, but the mount you might have to swap out, perhaps ?

 

[ScarlettRed]

I meant 6mil. It's a Tier One 33mm height for the ZCO 4x20x50. Close fit, but it clears. I think I may have to order a 0 mil mount as this new barrel wants to throw them higher than the scopes current adjustment. I finally got my muzzle brake off with a lot of heat and had to cut the crush washer off with a bandsaw. I disagree with you on recoil, at least in the 6.5. Damn, it is smooth and mild. Really felt great. We'll see what happens when I put on my suppressor today. My 20s's don't seem to muffle much under suppression. I've tried the OSS Ti, Ultra 7, dominus sr, and 338 ultra sr. The 338 does the best job, but still pops everyone's ears in the vicinity. Until this latest rifle, I've had nothing but stellar luck with the system. My most accurate semi's. I just love the system layout. I wouldn't mind a LMT MWS someday, but I have an mrp to satisfy that bug. Mile high looked at the pin and pin hole and thought they were nice & tight. I personally think that it was short chambered as after a couple misfires I had difficulty pulling it out of battery. The bullets had horizontal scars where I believe the bolt rotation left marks after the bullet was jammed into the lands. I tried an improvised ogive measurement and found at least .010 jamb. I'm not saying that is what the problem is, it could have been a headspace issue. Hopefully the new barrel keeps running great.

 

[psdan000]

I meant 6mil. It's a Tier One 33mm height for the ZCO 4x20x50. Close fit, but it clears. I think I may have to order a 0 mil mount as this new barrel wants to throw them higher than the scopes current adjustment. I finally got my muzzle brake off with a lot of heat and had to cut the crush washer off with a bandsaw. I disagree with you on recoil, at least in the 6.5. Damn, it is smooth and mild. Really felt great. We'll see what happens when I put on my suppressor today. My 20s's don't seem to muffle much under suppression. I've tried the OSS Ti, Ultra 7, dominus sr, and 338 ultra sr. The 338 does the best job, but still pops everyone's ears in the vicinity. Until this latest rifle, I've had nothing but stellar luck with the system. My most accurate semi's. I just love the system layout. I wouldn't mind a LMT MWS someday, but I have an mrp to satisfy that bug. Mile high looked at the pin and pin hole and thought they were nice & tight. I personally think that it was short chambered as after a couple misfires I had difficulty pulling it out of battery. The bullets had horizontal scars where I believe the bolt rotation left marks after the bullet was jammed into the lands. I tried an improvised ogive measurement and found at least .010 jamb. I'm not saying that is what the problem is, it could have been a headspace issue. Hopefully the new barrel keeps running great.

Did you run suppressed before you sent it back to FN? Did they give you any flack for removing the factory muzzle device? Curious as I've read they will void your warranty for evening changing out the muzzle device and definitely for running the gun suppressed. I just bought a scar 20s in 7.62 and am planning on running it suppressed. I also purchased a mototech 3 position regulator.

 

[ScarlettRed]

Don't tell em. Their policy is BS so never rat yourself out. That is my policy for lots of items as your own modifications are rarely connected to the problem. If you throw a 300 Blkout in a 556 chamber that's on you though.