cjt33 Posted February 2, 2016 Report Share Posted February 2, 2016 Bought a gently used (100-200 rds) Match legal Service Rifle. Acquired a NIB A4 upper receiver & BCG. Planned on swapping everything over to new upper receiver, then I thought 'Why not have 2 functional uppers??' .308 is a little boring for me, I have several bolt guns in this caliber. So 'Why not build something different?'. This lead me to the .260 Rem, mainly due to High BC's & OAL of the round. This was before I was aware of any of RRA's 'proprietary' components. I am aware this can be done, & with a little help from you guys, I plan on doing so. So fast forward 2-3 years, I have done absolutely nothing with this rifle or the new upper, haven't even shot the damn thing, sacrilege I know. Here's the rundown.LAR-8 A4 upperLAR-8 A2 lower w/ RRA's 2 stage triggerPlan on splurging on a 24" fluted Krieger varmit/bull contour in .260 RemingtonJP adjustable gas blockRifle length gas systemI understand the bolt needs to be headspaced to the new barrel. Will the adjustable gas block help with figuring out how to make this thing cycle?? Should I overbore the gas port, then start from 0 adjusting, so I KNOW it won't be undergassed?? Quote Link to comment Share on other sites More sharing options...
cjt33 Posted February 10, 2016 Author Report Share Posted February 10, 2016 Trying to load pics , getting message -'unable to complete previous operation due to low memory' Is there a way around this??Maybe because I'm using a mobile browser?? Quote Link to comment Share on other sites More sharing options...
cjt33 Posted February 10, 2016 Author Report Share Posted February 10, 2016 I acquired this Lar-8 3-4 years ago from a shooting buddy, I was told that this rifle was ordered from RRA with a Krieger barrel. The guy went back & forth with RRA on the barrel, said it was like pulling teeth to talk them into it, and he waited about 14 months to get it. Ran something like 100 - 150 rds through it & decided it wouldn't do what he wanted @ 1000yds (wouldn't stabilize 175 grain or heavier @ whatever MV his loads were pushing out of what I'm assuming is a 20 in 1-10 twist .308 barrel). So he offered it to me at a heavily discounted price & I jumped on it. This is my 1st & only large frame AR & I knew nothing about RRA's 'proprietary' components at the time. After lots of online research & discovering this forum, fast forward to now:Curiosity has got me as to whether or not this barrel is actually Krieger since RRA says that it can't be done. Looks like a standard heavy barrel (possibly HBAR profile). Since I'll have to remove gas block/sight post to get the handgaurd off, I looked under the handgaurd, the best I could, for a stamp or makers mark couldn't find anything. Then I looked at the barrel extension feed ramps, they are NOT Rock Rivers 'proprietary' wide single feed ramp, but what looks to me like standard M4 feed ramps. Looking more like this could actually be a Krieger barreled, factory assembled, RRA LAR-8 A2. I could be sitting on a frickin Rock River unicorn!!! I think I'll try to call them with a S/N to see if they can verify this or come up with a build sheet or something. Or I could just take off the gas block & handgaurd and see for myself. Either way if this barrel is indeed a Krieger, it may open the door to some new possibilities.1. Put the complete barreled A2 upper on the chopping block for some funds for .260 build. (Not sure if there's any Rock River service rifle guys on this site.)2. Abandon .260 build & swap Krieger .308 barrel over to my new A4 upper. Sell A2 upper receiver.3. Keep the .308 & proceed with .260 build at a slow pace (lack of funds lol)Either way maybe I'll finally make some time to see if this sumbitch'll actually shoot. Any input would be greatly appreciated, in the meantime I'm gonna try to get some pics uploaded. Quote Link to comment Share on other sites More sharing options...
cjt33 Posted February 10, 2016 Author Report Share Posted February 10, 2016 (edited) https://drive.google.com/file/d/0B18kndbPodsCRG5ZQ3puSG90Y1JmeUVsOEhMWENWMDNSVzU4/view?usp=docslist_api Edited February 10, 2016 by cjt33 Quote Link to comment Share on other sites More sharing options...
cjt33 Posted February 10, 2016 Author Report Share Posted February 10, 2016 (edited) https://drive.google.com/file/d/0B18kndbPodsCMkFDT0xucEFoZ1k/view?usp=docslist_api Edited February 10, 2016 by cjt33 Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted February 10, 2016 Report Share Posted February 10, 2016 (edited) OK ... So nobody has answered you , I will get onboard.1st question. As the gun sits ; can it fire ammo ,Now? Is the gun complete ?2nd . What ammo are you using ?175gr may be too heavy or too long for it to cycle. 150gr ,155gr or 168gr may be the ticket you could try.Please DONT start messing with the gas port yet !Also the RRA have (different size/type) buffer and buffer spring combo's than DPMS and Armalite.BTW, RRA is not know for their speedy service. Edited February 10, 2016 by MikedaddyH Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted February 10, 2016 Report Share Posted February 10, 2016 RRA Unicorn ! ? Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted February 10, 2016 Report Share Posted February 10, 2016 Reread the thread. You have a 308 barrel on the gun NOW . correct ! The 260Rem is what you are building ? Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted February 10, 2016 Report Share Posted February 10, 2016 What magazines are you using ???? Quote Link to comment Share on other sites More sharing options...
Tripledeuce Posted February 11, 2016 Report Share Posted February 11, 2016 (edited) My very first build was putting a DPMS bbl on a RRA upper. Everybody told me it could'nt be done. I'v been a working gunsmith for over 50 years. I checked everything out, put the bbl on the upper, torqued it to 40# and went out and fired it. I found I had to run a finish reamer in the chamber , by hand, as it seems DPMS likes "tight" chambers. Constant feeding failures led me to eventually opening the gas port one drill size. it now functions fine, and accuracy is all I could want. So far, I'v put 3 DPMS bbls on three different RRA uppers. They all shoot fine. Respectfully Terry Edited February 11, 2016 by Tripledeuce Spelling Quote Link to comment Share on other sites More sharing options...
cjt33 Posted February 11, 2016 Author Report Share Posted February 11, 2016 Thanks for the response Mike, I thought I was talking to myself for a lil bit..sorry if my posts are confusing.Currently have a fully functioning LAR-8 A2 'service rifle' in .308My dilemma is whether or not to swap .308 barrel (which may be a Krieger BTW) to new A4 upperOrPut .260 Rem barrel on new A4 upper, keep or sell .308 A2Using FAL mags Quote Link to comment Share on other sites More sharing options...
cjt33 Posted February 11, 2016 Author Report Share Posted February 11, 2016 Terry, likewise for the response. Are you still running your .260?? What kinda load has it preferred?? Have you been able to put any rounds down substantial distances?? Kinda think I'm working backwards, should've built a bolt .260 first & worked up some kinda load to start my gas gun with...hell I don't even have any dies Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted February 11, 2016 Report Share Posted February 11, 2016 Simplify things a bit. Get the gun you have working properly. Then start a new build with the .260rem barrel that you want on a Aero upper and lower set. You will be happier and have two working guns instead of one gun and two uppers. It going to cost a little more but it will be worth it in the end. Quote Link to comment Share on other sites More sharing options...
Tripledeuce Posted February 12, 2016 Report Share Posted February 12, 2016 (edited) My bbl likes 43g of IMR 4350 with a 140 Hornady 140 A-Max. Velocity is 2770. Under 1" at 100, don't have any longer range here. Respectfully TerryPS Sorry i didn't respond earlier. I'm not on every day. Edited February 12, 2016 by Tripledeuce Quote Link to comment Share on other sites More sharing options...
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