Frankh252 Posted February 10, 2016 Report Share Posted February 10, 2016 I have a new AR 308 that has about 200 rounds through it with no problems but I want to install a new keymod rail and lose the cheap plastic handguard. My question is whether it is necessary to check the headspace since I am using the original bolt and barrel. This is my first AR so I am learning. Recommended barrel nut torque is 44-50 ft/lbs but I don't know if the headspace changes with within the torque range...Just to pre-answer some questions that may come up: I have all the proper tools such as a bench vise, a breakover bar to remove the barrel nut and a new torque-wrench to reinstall the nut, a new Wheeler upper receiver vise block, gunsmith punch set, 2000 degree threadlocker, 1600 degree anti-seize, etc stuff like that. Weapon is a DPMS Oracle LR308 (yeah I know it's no masterpiece but it's only meant to be a cheap trainer before moving up). BTW, per DPMS the correct headgauges to use are the 7.62x51 NATO not the .308Win. I asked them about it is because the receiver is stamped .308Win but the barrel is stamped 7.62x51 Quote Link to comment Share on other sites More sharing options...
washguy Posted February 11, 2016 Report Share Posted February 11, 2016 Hi Frankh Welcome to the forum ! The headspace will stay the same ...no worries...headspace will not change with torque.... dont use threadlocker on the barrel nut...use anti seize.....most of mine are torqued bout 60lbs give or take...use your instructions that come with a new handguard for torque values...they usually give you some values...but you can go above 50 lbs...good luck.... post a pic of the new rail Wash Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 11, 2016 Author Report Share Posted February 11, 2016 (edited) Thanks Wash, I thought that would be the case about the headspace but I wanted to get the advice of the pros here before proceeding with barrel nut removal. Unfortunately, our local gunsmith has gone out of business so there aren't many options there. And yes, the threadlocker is for the gas-block set-screws, the anti-seize is for the barrel nut and the 44-50 ft/lbs is from the handguard installation instructions. It's a Fortis Switch 12", not that I want to switch it I just like the F logo and there's no gap where the rails meet. Will post a pic when assembled. Frank :) Edited February 11, 2016 by Frankh252 Quote Link to comment Share on other sites More sharing options...
survivalshop Posted February 11, 2016 Report Share Posted February 11, 2016 Thanks Wash, I thought that would be the case about the headspace but I wanted to get the advice of the pros here before proceeding with barrel nut removal. Unfortunately, our local gunsmith has gone out of business so there aren't many options there. And yes, the threadlocker is for the gas-block set-screws, the anti-seize is for the barrel nut and the 44-50 ft/lbs is from the handguard installation instructions. It's a Fortis Switch 12", not that I want to switch it I just like the F logo and there's no gap where the rails meet. Will post a pic when assembled. Frank :) We have had some that say theirs , do not meet & there's a gap . Interesting . Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 11, 2016 Author Report Share Posted February 11, 2016 survivalshop, could be it doesn't meet. Will know when installed 'eh? Just going by some of the reviews I read, so it's internet info about that so far... Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 12, 2016 Author Report Share Posted February 12, 2016 Started to do the rail install after work today but ran into a snag that's my own fault. The barrel nut wrench section of the multi-tool I bought is apparently only for an AR15 not the AR308 (it was advertised as being a combo AR15/AR308 tool). The inner opening on the wrench is not large enough to fit around the larger diameter section of the barrel to reach the nut. A friend has one I know will work, so I'll take another stab at it this weekend.About the gap/no-gap issue...here's a video of a Fortis Switch install with (what I consider) an insignificant gap. If this is what is considered a gap, it isn't enough of a gap to be an issue for me. A bigger issue for me is that guy in the video doesn't appear to torque the barrel nut with a torque wrench (unless they cut that scene). I'll use the torque wrench rather than doing it the way the video shows it being done. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted February 12, 2016 Report Share Posted February 12, 2016 As far as the Gap , my JP hand guards all have a gap , other brands of Hand Guards I have , do not & as you said , its not much of a gap , some want them to butt up the the Upper Receiver rail ( looks ? ), I guess they should look into another rail system . There is probably a reason for the Fortis rail system , not butting up with the Upper . The Barrel Nut torquing , some use a Torque wrench & some don't . With the type of barrel nut used by Fortis , there is nothing to keep the Barrel Nut from backing off , like notches in the Barrel Nut for the Gas Tube to pass through . If torqued properly , it should not move , I say shouldn't , but we all know $hit happens & if Barrel Nut not tight enough , its possible it may back off , but you should see the Hand Guard twist out of alignment , because its clamped to the Barrel Nut. Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 13, 2016 Author Report Share Posted February 13, 2016 I've done a lot of homework before putting a live round or tool to this Oracle but I didn't do enough. Lucky for me, I have intended for this project to be a hands-on training platform from before I even ordered the gun and it has certainly been that. I also have no doubt that I still have much to learn.Classic mistake this time, making an assumption: I thought this gun was a high-profile model but the picatinny rail is slightly higher than the receiver rail, so it must be a low profile model. And it does have a bit more of a gap than I expected but that still wouldn't be a real problem although I would prefer a closer fit. I can make use of it as is for now and maybe save the Fortis for a future build when I get a replacement for this one. Anyway, onward the steps go and I'm lovin' every minute of it!When I have better light tomorrow I'll get a a pic or two to post so everyone can chuckle at another rookie screwup! Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 13, 2016 Author Report Share Posted February 13, 2016 Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted February 13, 2016 Report Share Posted February 13, 2016 Yikes! Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted February 13, 2016 Report Share Posted February 13, 2016 Buy another upper that is the same height as the Fortis handguard ,then buy a lower height handguard another barrel ,,bcg ,gas block and compensator. Problem solved and the next gun is almost done!Don't sweat it ,just measure twice before you order anything . Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 13, 2016 Author Report Share Posted February 13, 2016 I should have got a caliper to measure the tang above the charging handle before ordering the handguard....yep. And no, I don't sweat the small stuff. Screwing up is how I learn best lol Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 13, 2016 Author Report Share Posted February 13, 2016 Since I do not have a caliper yet...measured with a combination square, the tang is 1/8" or very close to 0.125" in decimal form. It's a low profile Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 13, 2016 Author Report Share Posted February 13, 2016 I would like to shortcut my novice searching and ask for help from the experienced folks here...what I would like to put on it is a keymod rail that has no gap between the handguard and receiver, and is approximately 12"-13" in length. Anyone know of any selections like that? Quote Link to comment Share on other sites More sharing options...
unforgiven Posted February 13, 2016 Report Share Posted February 13, 2016 I have this om my M5 http://aeroprecisionusa.com/m5-enhanced-keymod-handguards.html and this on an 18" 5.56 but found one for .308 http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_ID=1230 Quote Link to comment Share on other sites More sharing options...
82HALO Posted February 13, 2016 Report Share Posted February 13, 2016 I also have this problem with the Forties handguard on my Aero upper, just the gap, height is perfect! Have a thread over in tools about it, was asking if lapping would help and if anyone knew where to get a tool for the 308. Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 13, 2016 Author Report Share Posted February 13, 2016 Many thanks unforgiven. Those are good looking rails no doubt and less than I paid for the Fortis lesson too.82Halo, my gas tube is very visible under the rail and I can't even see yours. Gas block not on when the pic was taken? If it is considered rude to speak to more than one person in a comment, please advise and I will rectify... Quote Link to comment Share on other sites More sharing options...
82HALO Posted February 14, 2016 Report Share Posted February 14, 2016 No, gas tube and block not on yet. Barrel came with a really sharp edged extension, I need to get in there and dull the edges and polish before assembly. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted February 14, 2016 Report Share Posted February 14, 2016 I think you may find that the Gap in the Hand Guard/Upper Receiver ,is all about how their Barrel Nut is made . You could alter their Barrel Nut , to take up the Gap , but may make the Nut lose some integrity. You would have to take material off the inside seating flange & as much off the the end of Nut , so it would not bind up against the Upper Receiver, before it Torqued the Barrel down. There are , as I brought up before , some reasons why they made it that way . I like my Midwest , ALG , & JP hand Guards & both my JP's have a slight gap , but the Rails are add on's & the holes for the screws are oblong , so as to make minor Rail adj. , for the rail to butt up to the Upper's Rail . Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 14, 2016 Author Report Share Posted February 14, 2016 82Halo, had I bought the correct height rail I could live with the gap. The feed ramps on mine feel a little rough but I haven't had any problems with it feeding so I'm leaving it alone. Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 14, 2016 Author Report Share Posted February 14, 2016 Buy another upper that is the same height as the Fortis handguard ,then buy a lower height handguard another barrel ,,bcg ,gas block and compensator. Problem solved and the next gun is almost done!Don't sweat it ,just measure twice before you order anything . I love that idea!"Hey honey, I screwed up and bought the wrong part, so now I have to buy a bunch of other parts to fix it." I think I'm coming down with gun-builders fever and don't want no doc. Quote Link to comment Share on other sites More sharing options...
washguy Posted February 14, 2016 Report Share Posted February 14, 2016 Frank and Halo you both have the same problemo I see....if it were me I would return those handguards and or barrels...both of those barrels look like they missed a machining step...those ramps are pitiful....ive never seen ramps that look like that. You all could have a mismachined barrel that could cause that gap or the handguard could be the problem....in any case I wouldnt have a rifle that looked like that...the uppers are different so I guess you could rule out the upper... im not dissing your builds but you should have a nice piece and not settle for that gap and then theres the barrel...yikes! Wash Quote Link to comment Share on other sites More sharing options...
guruofhotrod Posted February 14, 2016 Report Share Posted February 14, 2016 I would like to shortcut my novice searching and ask for help from the experienced folks here...what I would like to put on it is a keymod rail that has no gap between the handguard and receiver, and is approximately 12"-13" in length. Anyone know of any selections like that?SLR Rifleworks:http://slrrifleworks.com/index.php?route=product/category&path=66_107_113 Quote Link to comment Share on other sites More sharing options...
Frankh252 Posted February 14, 2016 Author Report Share Posted February 14, 2016 Frank and Halo you both have the same problemo I see....if it were me I would return those handguards and or barrels...both of those barrels look like they missed a machining step...those ramps are pitiful....ive never seen ramps that look like that. You all could have a mismachined barrel that could cause that gap or the handguard could be the problem....in any case I wouldnt have a rifle that looked like that...the uppers are different so I guess you could rule out the upper... im not dissing your builds but you should have a nice piece and not settle for that gap and then theres the barrel...yikes! WashThe barrel on mine is stock DPMS and doesn't have the sharp edge issue. I ordered the wrong handguard is all (bought a high-profile handguard for a low-profile receiver). Since it was my fault, I'll bite the bullet & keep it as a lesson. Might come in useful someday for someone with a high-profile DPMS LR-308. Quote Link to comment Share on other sites More sharing options...
washguy Posted February 14, 2016 Report Share Posted February 14, 2016 (edited) The barrel on mine is stock DPMS and doesn't have the sharp edge issue. I ordered the wrong handguard is all (bought a high-profile handguard for a low-profile receiver). Since it was my fault, I'll bite the bullet & keep it as a lesson. Might come in useful someday for someone with a high-profile DPMS LR-308.Oh okay...miss read thought you both had the same sharp ramp issue...so since they are two different barrels and two different uppers....then the fitment issue of the gap must be the fortis handguard........ and now after looking at the video and see how the rail attaches im thinkin they are trying to reinvent the wheel....who or why would need to quickchange the handguard with a clamping lever ? Wash Edited February 15, 2016 by washguy Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.