Hoot

This is kinda funny in an odd way. In my intro thread, I detailed the travails of removing and reinstalling the RRA handguard, which on the Predator HP serves also as the barrel nut, in order to send my barrel out to have the muzzle threaded. I knew it was going out on the mail truck today and since the truck does not come until around 5 PM, while the post office is open at 9 AM, I had them hold the barrel and drove the mile from my house to pick it up at 9, so that I'd have the day to play with it. It's back on and good to go, but my wife came home this evening from shopping and carried in a box from the front porch that the mailman left at 5 PM. In it was my DPMS 260 Remington Barrel that the place where I ordered it from had told me it was out of stock and I left it backordered since the price was significantly less than DPMS' recommended price. I wish the lady at the post office had told me that I had another box in the push cart to go out on the truck when I was there at 9 this morning, but so it goes. So, now I have my Zig barrel after having wrestled the 308 barrel back on earlier today. I did a headspace quick check using a freshly resized 260 Remington case and just like Terry (tripledeuce) observed, the chamber, when used with the RRA bolt, is a skosh short. Not more than a few mils I'd wager. I say that because despite the fact that a freshly resized 260 Remington case will not allow the lugs to fully engage, on a hunch, I tried a freshly resized 243 Winchester case and that case does. Back when 260 Remington cases were in short supply, folks were fireforming 243 Win cases to make them. Now I almost wish I hadn't discovered that fact as it leaves me in a quandary. I can do like Terry did and kiss the chamber with a 260 Remington reamer, enough to achieve the proper headspacing using the RRA bolt. That's going to leave me with a barrel that is no longer to DPMS spec, or in other words a custom barrel only suitable IMHO for mounting on an RRA LAR-8. If in the future, I no longer want it, the only person I could sell it to in a clear conscience would be an LAR-8 owner, though the minute, additional chamber length would not really compromise performance. I could however, buy some 243 brass, fireform it to my chamber condition and leave the barrel unchanged, or I can try to set up my 260 die to bump the shoulder back the mil or two it'll take to get the brass to work. Or, I could purchase an additional LAR-8 bolt and lap the lugs, leaving the barrel unchanged. If you knew me better, you'd know just how delicious a conundrum this is for me. I love challenges like this that take me outside the nine dots. Lastly, I'm kind of a "in for a dime, in for a dollar" guy. If I decide the re-ream the chamber and have to rent a reamer (if I can't borrow one) I may opt to make the chamber a 260 AI chamber at the same time. The improvements afforded by the AI 40 degree shoulder are akin to the benefits afforded by the 6.5 Creedmoor and I'd gain a small amount of case capacity for my trouble. IE, if it's going to be custom anyway, might as well go all the way. The winter is long up here and time is on my side. I will no doubt go to sleep tonight ruminating on the possibilities. Life is good... Hoot

Well, my barrel came back from having the muzzle threaded and the brake indexed and I must say, Jim Pixley did a fantastic job on it. He will get more of my business when I need that kind of work done. I doped the threads with Kopr Kote antiseize and got it to index on a gas tube hole while applying the proper range of torque. While getting a hole to index at the proper torque was my goal, I arrived at that point one hole earlier than the factory did and my sling stud is now 15 degrees off center. Fortunately, I don't use a bipod, so it's not a show stopper, but short of sourcing and purchasing the appropriate shim washer(s), it will look odd to the observant bystander at the range. My Safari Sling will not mind when I take it hunting though. It's actually supposed to get above freezing tomorrow, so perhaps I'll load up a few known-good loads and take it to the range for a short proofing session. Hoot

Though I'm relatively new to this forum, I've been doing the forums for about 10 years and before that there was listserv and of course usenet news. I've been to sites which after a short while, grew tiresome from all "seekers" chasing all the elitists. I think a sign of a good forum is one where you feel as comfortable reporting your failures and screw-ups as you do your accomplishments. That's truly an extended family. So far, despite having unfortunately chosen a brand that doesn't get much participation, I think you are doing a great job. I'm still discovering some of the sub-forums where I don't have a dog in the fight, but find folk's threads still interesting to read. The only improvement I would like to see would be a "Save Draft" feature for times when you're called away for a while. All in all, I'd say it's a job well done. Hoot

Given Tripledeuce's recent success adapting a DPMS .260 Remington barrel to his LAR-8, I am pondering my 2012 project caliber, based upon my LAR-8 Predator HP rig. I dearly love the 6.5mm bullet, so my immediate goal is either a 260 Rem or 6.5 CM. Here's my decision factors regarding one over the other: 260 Rem: I already own a Savage Model 12 Thumbhole Varminter with a 26" EA Brown bull barrel that is boringly accurate, so I already have dies, brass, load workups, etc. I like that the 260 Rem chamber reamer is based upon a 2.80 COL and has a shorter leade/throat designed in than the Creedmoor's chamber reamer. I like seating at or real near the lands, but have to live within the confines of my FAL magazine's COL. I like the 6.5 CM shoulder angle better and its shorter case length. The latter again, being to work with the magazine limitations, though it has a longer leade/throat by design. I would have to buy dies, brass and work up load data, but then the last part is what I enjoy as much as anything about shooting. It's always entertaining, breaking new ground. Barrels cost the same, regardless of which way I go. Unfortunately, I thought I had a line on an affordably priced DPMS 24" bull 260 Rem barrel based upon a web site, but when I called to verify availability, they had just sold the last one. So there went the economic advantage in terms of barrel cost. In terms of reloading, I'm not the guy agonizing over milking the remaining few fps from a cartridge at the cost of accuracy, so each caliber's upper velocity limit claim is not as important as inherent accuracy with a wide range of bullet brands and weights. If you're wondering about dimensional difference specifics, from the SAAMI site: 260 Chamber length 2.045 Case length 2.035 -.020 Leade/throat .221 6.5 Chamber length 1.9408 Case length 1.92 -.020 Leade/throat .361 Anyone care to wade in? Hoot

Just to be clear. If you mic the maximum thread dimension on the receiver, it measures 1.426 inches. That is within the range of values yielded by a 1-1/2 - 18 die which varies depending upon the Class of thread and the die manufacturer. Your 1.437 inches is also within the range of values yielded by a 1-1/2 - 18 die. There's that much thread variation in dies. For example, I have some 5/16-24 stainless screws that mic at .3045, not .3125. Still, they're called 5/16-24. Hoot

Here are images that apply to the discussion: Barrel Profile Barrel / Receiver Junction FFT Threads Hoot

The Model of my LAR-8 is the Predator HP. The Barrel is 20" SS with an odd profile not like any mil profile I've ever seen. The barrel is marked 3-223S/ The receiver thread appears to be 1 1/2-18TPI. There are 8 threads, so an FFT or barrel nut must be deep enough to allow 8 turns and a little length past where the threads end to where the receiver body occurs for a total depth of .625. There is no barrel nut. The FFT body is the barrel nut. It's late, but I will try to get some images up tomorrow. Hoot EDIT: Did some googling and the 223S means "Stainless NM (rifle) unthreaded muzzle". No idea what the 3- or the / means

Good News! I'm a tenacious person WRT problem solving, in that I have a hard time knowing when to throw in the towel. Some times it leads to success through perseverance and some times it leads to a lot of lost time and only then throwing in the towel. I've been a little obsessed with getting this LAR-8 barrel off, so I could send it out to have the muzzle threaded and I've already written of that challenge yatta yatta... ::) A local, fellow, amateur smith and I were talking this morning about it and he had an idea of employing a second Rigid strap wrench on the opposing side of the handguard to bias it more to the centerline of rotation, when applying pressure. The basis being the nature of aluminum on aluminum wanting to seize under pressure and whether applying the strap wrench to just one side was perhaps offsetting the stress to the other side and precipitating that binding. Even in the presence of alleged anti-seize. He too has worked on his share of AR platforms both for himself and others and has the exact same model (#2) of Rigid strap wrench as I have. So he came over and we chucked the receiver in the fixture. He got on one side and I on the opposing side with our wrenches. Also, having tested the anodizing in an inconspicuous area for heat tolerance already, I applied heat to the handguard directly over where the threads were. On the count of three, we both gave it a yank and sure as you bet, it broke free. No barrel nut. Just the handguard holds the barrel in, but then I've seen that on other ARs with an FFT from time to time. In RRA's defense, they did use anti-seize on the threads. Looked like the standard Zinc and Vaseline stuff you can buy. I prefer Jetlube KOPR Kote myself and that's what it's going back on with, but to each, his own. Score one for the good guys. <thumbsup> Now, I've got to find the contact info for the fellow up north of me who threads muzzles. Back to work tomorrow... :( Hoot

Unless they've changed the formulation, I believe Militec, which I have used in the past, only works, or works best on regular steel, but not stainless, chromed or nitrided steel. It also does not work on aluminum. It reacts with steel very well if you heat it up, but it has to be in contact with the steel, not sitting on the surface of whatever the steel is coated with, as in bluing, parkerizing, etc. It worked well for me. I have not tried "Ed's Red" or other concoctions based upon ATF or MTF, though they have quite a loyal following among those who do. Hoot

I'm not a rock-n-roller at the range and I hunt with my ARs. I find the RRA NM triggers perfect for my shooting needs in them. On bolt actions, especially ones that rarely go out into the field, I like a lighter trigger as it does impact groups when you're in the sub-MOA groove. I have not worn out an RRA NM trigger group yet, but that's just me. I do hold my lower upside down and brush it out with a flux brush when I clean at the end of a range session, but I wouldn't say I obsess over it. Likewise, I keep mine lubricated with a little Molykote G-n paste as it is a precision device and there is no point in allowing it to wear unduly. A little goes a long way with the paste. In defense of those who run more expensive 2-stage trigger groups. I have never tried one, so I can't say conclusively whether there is a performance difference worth the cost difference. I do know myself though. If I were in a situation that relegated money to not being an issue, I would already have tried every flavor of trigger group out there. Unfortunately, I was born with a plastic spoon in my mouth. ;) Hoot

My new LAR-8 did a similar thing, though not as bad as he had. I approached mine as an over-gassing issue, but neither additional buffer weight, nor adjustable gas block helped. If the bolt rotated, the ejector swiped the head. Looking under a stereo microscope at the bolt face, it didn't have any obvious burr like his did in the pictures on page 1. What fixed my problem was rather low tech. I removed the extractr and ejector, chucked an old .308 case in the drill press. I put a dollop of 600 grit lapping compound onto the bolt face, lined the two up carefully and polished it using the brass case in the drill until the phosphating was just barely effaced. No more swipes. While the fix bandaided the problem, it is still being caused by the bolt trying to unlock while the brass is still siezed to the chamber wall, so the problem is still one of timing dwell. The adjustable gas block was fussy to implement in that when set to where it would cycle one round, there was no consistent repeatable guarantee that the next round would cycle and that was using the same loads. I didn't want to have to tweak it each time I changed loads as well. I suspect the proper solution would be to move the gas port and block a little further down the barrel or using one of those folded back upon itself, longer gas tubes, if you can still find them. The ones with the extra stub hanging off of a manifold are not the solution. Actually, I never understood why they even exist. <dontknow> Hoot

Though I prefer Kroil for cleaning and protecting my bores, none of which get stored for extended periods of time, IE more than a few months without being shot and cleaned again. I previously used Breakfree CLP for general weapon cleaning and light lubricating. A fellow turned me on to a free sample of Weapon Shield, made by the fellow associated with FP10 and I must say, the CLP is now relegated to less critical lubrication assignments. The 16 oz bottle of Weapon Shield costs a few dollars more than the same amount of CLP, but my experience with it leads me to not mind paying the difference. Google the product and drop them an email for a free sample. For heavier lubing, like where metal on metal occurs, especially phosphated and annodized metal on metal occur, you can't beat Dow Corning Molykote G-n Paste. It burnishes into the surface and reduces friction very well. you can get 2.8 ounce tubes of it Here among other places and a tube will last you years. Great on bolt lugs, slides, charging handles and their channels, wherever high pressure friction occurs. If you MoS2, WS2, or HBN coat your bullets, you can make a close approximation of it by mixing a small amount of the powder in a few drops of CLP or Weapon Shield, to the consistency of grease and applying it. I have treated some AR15 bolts and receiver rails with it and after 1k rounds, the parkerizing or anodizing still hasn't worn off the underlying metal surfaces where they ride on. It's also helpful when applied with a q-tip to the cam pin and mating slot edges. While it won't keep the battering from taking it's toll at the end of it's travel, it will reduce the grooving that it eventually winds up sustaining from friction sliding along the slot edges. Just a few ideas for other clean and lube freaks like me. ;) Hoot

Thanks for the link. Though I had heard of a 7.62 AR platform based upon the G3 magazine, I had not known the particulars. It did make me curious enough to go measure the one G3 mag I had left from back when I owned mine. Based upon that mag, it will tolerate up to about 2.875 COL, which though not earth shattering, is an improvement worth noting. Those 168gr Amax' hit the lands at 2.89. I mentioned the nice fitting L1A1 mag that came with my LAR-8 allowing 2.82 COL. I still have a metric FAL mag from back when I had my Izzy and surprisingly, it edges out the L1A1, coming in at 2.84 COL. Not enough to get excited about though. With the shorter leade and throat afforded by the chamber design that RRA uses in the LAR-8 PHP, I suspect magazine COL limitation will not play such a key role as it did with my .300 OSSM (WSSM) I recently parted with. Olympic utilizes a much longer leade and throat in that chamber and long ogive bullets have quite a jump from the magazine limited 2.26 COL to where they engaged the lands around 2.46 to 2.56. There's a good example of how risk mitigation lawyers can screw up a design. Had they used a shorter leade and throat, I believe more bullets would have shot accurately from it. By accurately, I mean MOA or less. I still have a half inch thick stack of targets from different bullets that perform admirably in other .30 caliber cartridges that shot 1 1/2 to 2 1/2 inch 5-shot groups at 100 yards in the .300 OSSM. That's an example to me of not accurately. That's why despite it producing some awesome velocity, IE 150gr Speer HotCor up to 3015fps, it is no longer my upper. Though the .308 gives up some umph to the .300 OSSM, I'll take the improved accuracy any day. Add to that, the fact that only Hunting Shack Munitions makes one (150gr) commercial ammunition loading for that caliber and it running $2.50 per round (shipped), the non reloading shooter is seriously hampered in terms of ammunition. Certainly not a rifle to take out plinking, unless you have deep pockets. ;) Hoot

I zeroed the scope using the aforementioned XM-80 and that was where the 168's flew. In the interest of not changing any more variables than I had to, I let the rounds hit where they chose. I was more interested in the groups than scope zero. Also, I shot all 20 in a round robin to reduce the chance of one lucky 5-shot group skewing the results. The CCI 200 group was comprised of shots #4, 8, 12, 16 and 20. I ran right up to deer opener fiddling with it, so I did not zero it out and take it this year. Main deer upper for close in is my 450 Bushmaster. Most of where I hunt in northern MN is thick as the hair on a dog's back. Then there are occasional sloughs, marshes, or long stretches of old logging trails. For those scenarios and as my backup caliber, my other upper was a 6.5 Grendel. IMHO, the most accurate out-of-the-box, AR15 platform caliber made. My worst 100 yard 5-shot group with it has been thumbnail sized, with pinky nail sized being common. Makes a shooter like myself look like Vasseli Zaitsev ;) Hoot

I've only recently joined this forum, having also recently purchased an RRA LAR-8 Predator HP. I was lucky in that the first load I worked up for it shot a ragged hole for 5-shots at 100 yards. All that is fine and good, but I like to experiment with reloading and the .260 Remington is a fantastic caliber, for which I already have a bolt action rifle in. Which barrel manufacturer(s) will profile a barrel for the LAR-8 and how do the costs range in price? I assume you shopped around for a barrel manufacturer? how much was the proprietary barrel extension from RRA, assuming you bought it separately from whoever made your barrel? Thanks, Hoot

Thanks imchur. I am still reading around the other sub-forums, but it looks like a you run a decent group of members. I'm big on civility and open-minded forums, with a minimum of trash talk. Life's too short... I thought I uploaded my hallmark avatar's URL, but I'm not seeing it in my post. Perhaps I did something wrong as even though it seemed to accept it, the next refresh showed "no avatar" selected. Is there a minimum post for your avatar to show? What is the dimensional pixel limt? Perhaps mine was too large, though I tried two different sizes. Hoot EDIT: Guess I could use a dose of patience. My avatar suddenly showed up while reading another sub-forum. H-

Greetings folks. In browsing for AR 7.62 platform forums, I noticed this one had more activity than some of the others, so the community here must be more engaged. Having burned out trying to work up accurate loads for my .300 OSSM (WSSM) AR15 upper, I sold it and and put the money towards a more conventional .308 AR rifle. Unfortunately (not totally) I misread an article in the July Shooting Times about the LAR-8 Predator HP. It gave me the impression that the upper and magazine combination would allow longer COLs than 2.80, which appealed to me in the interest of loading rounds with high BC bullets and not having to sacrifice either powder capacity or bury the ogive beneath the case mouth. Also, if I chose, I could load them long enough to be at the lands. I read wrong. When my LAR-8 arrived, it came with a new L1A1 FAL magazine that accepts rounds up to 2.82 COL. Certainly not the .5 inch increase I misunderstood it to afford. There were other positive attributes that drove my decision and the promise of other caliber uppers besides the .243 and 7mm-08 currently offered. Given the rise in popularity of 6.5mm (.284) caliber cartridges, I don't understand why RRA did not come out of the chute with either a .260 Remington or 6.5 Creedmoor upper. I have a .260 Remington tack driving bolt action already. Hopefully, they will in the future. Having since shot a friends .260 DPMS, I am feeling a slight amount of buyer's remorse though. Ditto on another associate's .338 Federal. Hopefully, this model does not become an orphan and RRA gets creative in their future upper caliber selections. The rifle is a class act nevertheless. Fit and finish are excellent. After totally disassembling it other than pulling the handguard and barrel (that's another story) and giving it a thorough cleaning. Lubed it. Reassembled it and took it off to the range for some familiarization and break-in using some LC XM-80. I've owned some .308 battle rifles, including an Izzy FAL, M-14S, G3 and converted M1 Garand in my time. The LAR-8 PHP, right out of the box shot the best 100 yard groups with XM-80 of all of them, averaging about 1.5 MOA off of my benchrest setup. Feed and Extraction were 100% and it really throws the brass a long way when I took off my catcher. The bolt has an incredibly strong ejector spring. It did however, leave crescent ejector swipes on every case head. I don't care for that as that's one of my checks for reloads that are approaching too hot. I approached the problem as one of being over-gassed. I increased my buffer weight from 4.6 ounces to 6.0 with no change. I added a PRI adjustable gas block, adjusting it across the spectrum, again with no change. I then went lower tech and simply polished the bolt face just enough to remove the phosphating and hopefully any burrs and that did the trick. I went back to the factory gas block, but left the additional buffer weight in as it tamed the cycling significantly, not beating up the spent cases as much. Still need to get a slightly softer ejector spring though. For my first reloading attempt, I chose to load up some Hornady 168gr Amax ahead of 41.7gr AR-Comp powder, from the ATK web site, since that powder is not chacterized in QuickLoad yet. For an element of variability, I tried that load with four different primers to see what it preferred. Here's the resultant performance: And the resultant 5-shot 100 yard groups: I was surprised to get the best group from the cheapest primers. The comfortable weather shooting season is over for the most part, but I hope to get many days of enjoyment experimenting with other loads when spring arrives up here next April/May. WRT the handguard. I like running brakes on my rifles, for reacquisition of target and for all day range sessions. Unfortunately, RRA chose not to thread the muzzle and one of my first tasks was to remove the barrel and send it out for threading. I bought the receiver block and the recommended heavy duty strap wrench, but could not get the handguard to budge. Having now had two different gunsmiths decline threading the barrel when they could not get the handguard loose in their shops and fearing damage to the receiver if they used more force, I am getting ready to send it back to RRA to have them loosen it. Whatever gorilla put it on at the factory, had no regard for torque specs, though the factory rep assured me "They always use anti-seize" when installing them. If something gets trashed, let it be on their nickel. There is no excuse for using that kind of force installing a handguard. If the gas tube hole doesn't align at proper torque, that's what handguard shim washers are for. >:( Anyway, kind of a long initial thread, but I'm long-winded anyway. Rest assured, I'll share my joys and sorrows as I get to know this rifle. Look for plenty of range reports come this spring. In the mean time, I'll be looking for a source for an aftermarket .260 Rem, .300 SAUM, or .338 Fed barrel if RRA does not come out with one or more in the future. I do love experimenting with the fringe calibers in ARs. Hoot