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 Post subject: 762-SD and Rock River LAR-8
PostPosted: Wed Apr 13, 2011 11:58 pm 
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Location: Boise
I have a 762-SD that I've been running on a LAR-8 308 and was wondering if anyone has heard of an overgassing issue with the Rock Rivers when supressed. I've shot about 80 rounds suppressed through the RR and ended up with a broken bolt catch. I talked with RR and they believe that the suppressor may be causing an over-gas condition slamming the bolt back harder and breaking the bolt catch. Not too sure that I buy that since the travel from a stopped position at the end of it's travel to the bolt catch is minimal with no real time for inertia to build up and cause a whole lot of damage.

Any thoughts on softening the suppressed force just a bit? Maybe a buffer pad? I wish Noveske would come out with a 308 Switchblock........


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 Post subject: Re: 762-SD and Rock River LAR-8
PostPosted: Thu Apr 14, 2011 9:53 am 
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jlindholm70 wrote:
I have a 762-SD that I've been running on a LAR-8 308 and was wondering if anyone has heard of an overgassing issue with the Rock Rivers when supressed. I've shot about 80 rounds suppressed through the RR and ended up with a broken bolt catch. I talked with RR and they believe that the suppressor may be causing an over-gas condition slamming the bolt back harder and breaking the bolt catch. Not too sure that I buy that since the travel from a stopped position at the end of it's travel to the bolt catch is minimal with no real time for inertia to build up and cause a whole lot of damage.

Any thoughts on softening the suppressed force just a bit? Maybe a buffer pad? I wish Noveske would come out with a 308 Switchblock........


two different issues-

1. Rock River's gas port is probably onthe large side to function with weaker commercial ammo.

2. Adding a suppressor can overgas such a system, but the effects of this would be greater recoil, gas in your face, failure to strip rounds from the mag... if it's going to cause parts breakage, it would most likely be a bolt lug. i agree that the bolt catch should be reasonably safe.

I have not looked into the options for an adjustable 308 gas block... A switchblock would be perfect. anyone else, ideas?

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 Post subject: Re: 762-SD and Rock River LAR-8
PostPosted: Thu Apr 14, 2011 10:08 pm 
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Joined: Sat Apr 09, 2011 2:26 pm
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Location: colorado springs
I have the RRA lar8 A4 20" with rifle length gas system, free float tube and an AAC 762SD. I was having overgassing issues and the blast coming out of the action was extreme. I didn't experience any broken parts but I only fired 5 rounds and decided I should stop. Shooting Federal 168 GM match the brass was landing in another zipcode. I have tried one type of adjustable gas block that works via a set screw. BAD IDEA. They are not really designed for this application. I have also tried a 3 position gas block that has a switch on the side. There is no lock for the switch and sometimes it will turn itself to "off", no good. I installed a noveske switchblock 5.56 rifle length. The gas tube is .400" shorter on the switchblock than on the factory RRA tube. With the SB set on "S" I had a dozen failures of the bolt to lock back after the last round and one failure to eject for the first couple mags. I have had at least 500 rounds of Federal factory, German 175 gr surplus, 112gr-118gr-125gr-150gr-168gr handloads since the last malfunction without a hiccup (and without any cleaning). I must also state for the record that this rifle wasn't fully broken in before the SB was installed. There hasn't been any overgassing issues since I installed the SB and I would know right away as I shoot Lefty. I will continue to shoot this rifle everyday suppressed with the Noveske and 762SD ( without cleaning) to see what I can expect from it.

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 Post subject: Re: 762-SD and Rock River LAR-8
PostPosted: Fri Apr 15, 2011 10:50 am 
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eastplace wrote:
...


Awesome!

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