Author Topic: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.  (Read 12650 times)

PegLeg45

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #10 on: March 21, 2010, 09:32:50 PM »
Rastus, the guy I mentioned in my first reply was telling me during our discussion that he was working on a short-barreled model 700 in .308. He had a spare factory barrel left over from a project on one of his competition guns and I believe he said he had cut it down to 16 1/2" just to see if it would shoot well. I think he said it surprised him with the accuracy. He was out of town at a competition this weekend, so the next time I talk to him I'll ask again to be sure.
"I expect perdition, I always have. I keep this building at my back, and several guns handy, in case perdition arrives in a form that's susceptible to bullets. I expect it will come in the disease form, though. I'm susceptible to diseases, and you can't shoot a damned disease." ~ Judge Roy Bean, Streets of Laredo

For the Patriots of this country, the Constitution is second only to the Bible for most. For those who love this country, but do not share my personal beliefs, it is their Bible. To them nothing comes before the Constitution of these United States of America. For this we are all labeled potential terrorists. ~ Dean Garrison

"When it comes to the enemy, just because they ain't pullin' a trigger, doesn't mean they ain't totin' ammo for those that are."~PegLeg

Overload

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #11 on: March 22, 2010, 06:14:24 PM »
Yeah that's why I wanna chop it off...

Wanna sell that FS 2000?  I might be interested.
Strangely enough there's a Yankee Hill Phantom flash supressor sitting on the end of my FS2000.  If only I owned a Yankee Hill Supressor...

Why is the date important with the FS2000?
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Rastus

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #12 on: March 23, 2010, 06:07:30 AM »
Strangely enough there's a Yankee Hill Phantom flash supressor sitting on the end of my FS2000.  If only I owned a Yankee Hill Supressor...

Why is the date important with the FS2000?

Yankee Hill Phantoms thread AAC cans too.....it's what I have for my M4-2000. 
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It is the argument of tyrants; it is the creed of slaves.
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Rastus

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #13 on: April 04, 2010, 08:20:09 PM »
T minus two weeks.  Gotta get a good mil dot scope.  30mm tube and I think 50mm objective.  I've been perusing the scopes and it may be August or so before I can afford one...pretty pricey.
Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves.
-William Pitt, British Prime-Minister (1759-1806)
                                                                                                                               Avoid subjugation, join the NRA!

PegLeg45

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #14 on: April 05, 2010, 04:37:37 PM »
T minus two weeks.  Gotta get a good mil dot scope.  30mm tube and I think 50mm objective.  I've been perusing the scopes and it may be August or so before I can afford one...pretty pricey.

Rastus,

I sent you a PM.....(cause I was too lazy to look up this thread  :P )...about my friend's short-barreled .308.

Peg

"I expect perdition, I always have. I keep this building at my back, and several guns handy, in case perdition arrives in a form that's susceptible to bullets. I expect it will come in the disease form, though. I'm susceptible to diseases, and you can't shoot a damned disease." ~ Judge Roy Bean, Streets of Laredo

For the Patriots of this country, the Constitution is second only to the Bible for most. For those who love this country, but do not share my personal beliefs, it is their Bible. To them nothing comes before the Constitution of these United States of America. For this we are all labeled potential terrorists. ~ Dean Garrison

"When it comes to the enemy, just because they ain't pullin' a trigger, doesn't mean they ain't totin' ammo for those that are."~PegLeg

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blackwolfe

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #15 on: April 06, 2010, 06:29:49 PM »
Rastus, is that LAR-8 going to get finicky, operational and reliability wise,  when you start chping the barrel down?  Does RRA offer it in a shorter barrel?  I thought I read somewhere once upon a time that the .308 AR styles can get problamatic with shorter barrels.
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Wolfe

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #16 on: April 08, 2010, 05:44:04 AM »
Rastus, is that LAR-8 going to get finicky, operational and reliability wise,  when you start chping the barrel down?  Does RRA offer it in a shorter barrel?  I thought I read somewhere once upon a time that the .308 AR styles can get problamatic with shorter barrels.

I'll keep that in mind and look it up.  I'm going to be running a can on it so there will probably be more gas coming back anyway.  Thank you for the comment, it is something I should check on before having that barrel whacked off.
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LogansRun

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #17 on: April 27, 2010, 03:26:40 PM »
New here.  I am getting suppressor (YHM Phantom 7.62 with QD), which is readily attached to most of my rifles.  Exception is Rock River LAR-8  26-inch heavy bull SS.  Just beginning to think about this rifle.  Can someone guide me a bit here?  Suspect need to cut down length and add threading.  But who/where to get this done and likely how much $$?  Any advice is appreciated.  Thanks.

Rastus

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #18 on: April 28, 2010, 06:08:58 AM »
New here.  I am getting suppressor (YHM Phantom 7.62 with QD), which is readily attached to most of my rifles.  Exception is Rock River LAR-8  26-inch heavy bull SS.  Just beginning to think about this rifle.  Can someone guide me a bit here?  Suspect need to cut down length and add threading.  But who/where to get this done and likely how much $$?  Any advice is appreciated.  Thanks.


I'd say ask your dealer who is a good gunsmith with a lathe.  All you need to do is turn down the barrel to the proper diameter at the end and thread it....threading it might be a chore unless they turn it down several inches which may look funky. 

For me, I've had mine for over a week and will shoot it this week (provided I get the scope rings from RRA in).  I've got a plan for mine based upon 1) stiff short barrels are more accurate than longer barrels and 2) .308 is optimized for 20 to 22 inch barrels in the match ammo and police ammo.

Here's what I'm going to do with mine and I hope to put pics up on it:

1.  Lap the scope rings to square them up.
2.  Record every shot by ammo type and manufacturer.
3.  For the first few rounds, chrono every round and clean after every round until the patches come back "clean" after the first few shots.  The 26" barrel is cryo treated and lapped so this may not be necessary...I'm obsessive.  If my patches come back dirty to start and clean up as the barrel is burnished I'll let ya'll know.
4.  The barrel starts at 26" and unless it groups 3/8" or so at 100 yards I'll cut it to 23".  If I cut it I'll have chrono for everyone to compare with.
5.  If the barrel is good at 23" I'll leave it...if the group stinks' I'll get the smithy to cut 1/2" or so off and try it again.  Again, I'll chrono.
6.  I'll continue to cut the barrel down to 21 or so inches to get a shooter...chrono along the way as I cut. 
7.  When it's a shooter, if it's a shooter, I'll have the end of the barrel turned and threaded for my can.
8.  I'll have chrono and groups with and without the can.

Now, hopefully I'll be industrious and dilligent enough to follow through with all of this.  It will be interesting to get real life chrono data and several different ammo's down the barrel with groups.  If I am really diligent, I'll chronicle with pics.

Anway, this is what I'm planning on doing...hope I didn't bore anyone and DON'T HOLD YOUR BREATH WAITING TO SEE WHAT HAPPENS GUYS.

BTW, I went to Optics Planet and got a Bushnell 4200 FIRST FOCAL PLANE 6x24 power scope with 30 MM tube for under $800 delivered.  1st focal plane is what you want and I had no idea you could get one for under $800 this quality...I thought I'd have to spend over $2k to get one and it has 1/10 moa clicks.  First focal plane means the mil dots are good at any magnification, not just one specified magnification.

Have fun with whatever path you follow.
Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves.
-William Pitt, British Prime-Minister (1759-1806)
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blackwolfe

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Re: Rock River LAR-8 and Gemtech Looming....need 308 tech advice.
« Reply #19 on: April 28, 2010, 06:37:39 PM »
Rastus, Are you cutting the barrel down yourself?  If you are and don't mind putting the extra time into it it might be interesting to try cutting an inch back at a time and chrono it inch by inch to see how it drops.  You wouldn't need to recrown it every time, unless you wanted to shoot it for accuracy also, just take a hacksaw to it. :)

I posted earlier about AR based .308s being finicky with shorter barrels, but I see that the Remington R-25 has a 20" barrel and you can get the DPMS LR-308 with a 18" barrel so I would think that at least down to 18-20" barrels shoudn't be a problem.  Maybe I just read some bad internet advice somewhwere about shorter barrels being a problem in .308 ARs

Looking forward to seeing your pictures and reports.
"We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution, but to overthrow the men who pervert the Constitution. "    Abraham Lincoln
 


Wolfe

 

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