Installation of LR-308 handguard (JPE 15") Problems [Archive] - Glock Talk

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93GT
12-10-2012, 04:03
I replaced the factory handguard on my LR-308B on Saturday morning. I had already replaced the gas block with the DPMS SASS low profile version and verified function and zero a couple of months ago. About a 2" group at 200 dead center with 3 round shot in under a minute. Right where it should have been after tossing the QD mount and scope back on.

Yesterday afternoon I take the same rifle back with the same ammunition (165 gr Accubonds at 2550 fps) with the only change being the handguard and at 100 with the same scope I am getting 3 or so inch groups from a steady rest. Let it cool down, take it to 200 and I can still hit a metal ram, but groups are getting so big that I wouldn't bother taking it out to 300. This from a rifle that I was easily taking to 500 yards with the same scope.

If I hadn't been shooting this thing for 3 years with much better results, I wouldn't be so surprised, but it has always been an MOA or better rifle. I just hated the short handguard. I am taking this thing black bear hunting this week, but shots will be under 100 yards so the degraded accuracy shouldn't be a concern there. I would really like to fix this thing that I messed up since I have over 2k invested for it to shoot 3 MOA.

Does anyone have any idea what I did to cause the sudden inconsistency? I checked the tube, it isn't hitting the gas block. I followed the instructions sent with it to the letter. It makes me wish that I would just just thrown the rifle length LR-308 tube on the existing collar and called it a day.

Mayhem like Me
12-10-2012, 04:46
I have installed one and they are tricky ,did you install the collar/ barrel nut with thread locker as they advised and wait 24 plus hours....this is very important.
Then getting a good moly grease on the outer barrel nut that threads in the tube is important I tourqed it three times the went to the final reading.

humanguerrilla
12-10-2012, 04:55
Not with the heatsink is it? Possibility barrel nut is not torgued tightly enough?

Big Bird
12-10-2012, 06:00
Re-torque and be sure to use a moly lube on the threads. Torque to spec and loosen three times to help mate the threads. Lastly, check gas tube alignment. Make sure your BCG will slide freely past the BCG under its own weight with the upper detached from the lower and at a 45 degree angle or so.

Don't be afraid to give it more torque than spec. Colt torques the crap out of their barrel nuts--WAY more than the TM specifies.

faawrenchbndr
12-10-2012, 07:25
I have installed one and they are tricky ,did you install the collar/ barrel nut with thread locker as they advised and wait 24 plus hours....this is very important.
Then getting a good moly grease on the outer barrel nut that threads in the tube is important I tourqed it three times the went to the final reading.

This is key..........did you use a torque wrench?
What wrench? When wad it calibrated? What torque?

93GT
12-11-2012, 17:48
Used a torque wrench, just a Kobalt from Lowe's. I am going to back through and check all of those things this weekend. I am regretting using all of that blue loctite now, but at least I didn't use the red. I did wait about 30 hours before shooting it after assembly. Probably didn't torque it down tight enough and there may be some slight pressure on the gas tube to cause it to be off center. Thanks for the tips, I will go make some more mistakes and report back.

93GT
12-11-2012, 17:57
I guess I didn't read enough before I did it. I spent a decent amount of time researching before I did it, but it would have been better if I knew anyone in my area that could have kept me from making stupid mistakes lol.

93GT
12-11-2012, 18:25
Yeah, I feel like a complete idiot now. I missed a critical portion of the directions that were not printed clearly in the instructions (bottom half looks like they were running out of ink). Now looking at the instructions online, knowing the remainder of step three seems exponentially more important than it did Saturday morning.

I blue loctited the six flat head screws like it says though lol. Don't worry about that. I just bent the torx wrench that came with the tube. I think I will just wait until Saturday when I have the time and can lay out the proper tools to start working on it. I am most likely going to get frustrated and break something by trying to fix my mistakes after long work days. Looks like the bolt gun is going bear hunting.

Removing things that have loctite on them? Obviously I will need a new torx bit. Propane torch to heat them up and break the loctite? I believe that my problem involves not using red loctite on the barrel nut and not tightening the inner nut to 50-80 lbs judging by everyone's comments and going back over the complete set of instructions. Now I just need to find the proper tools and patience to fix this thing without breaking it.

Big Bird
12-11-2012, 18:56
I've never heard of red-loctite on a barrel nut. Usually its some moly based grease.

A little heat on the screws will loosen up that blue loctite. Just heat and try...heat and try. Easy does it.

50-80 ft lbs is pretty good. The TM for an AR specifies something like 39 ft/lbs. But as I said, anyone who's taken a barrel off a Colt built gun knows they more than double that torque on their guns. My 6.8 SPC I builty using a Noveske NSR rail took nearly 90 ft/lbs to get it to line up properly. I was a little concerned but when I talked to the tech at Noveske he said not to sweat it. They have to tighten a little past specs all the time to get them lined up properly Gun runs like a champ.

humanguerrilla
12-11-2012, 19:13
The barrel nut on 308 and heavier recoiling cartridge ars need to be tighter. Seems Dpms got rid of the forums with info on their site but you could call/email them, jp, or fulton armory. Ar10 is 70plus ft.lbs. Tighten to 50, loosen then tighten to 60, loosen then tighten to 70 then as necessary for alignment.

Mayhem like Me
12-12-2012, 04:58
BB
The first barrel nut on a JP is basically a extension to the receiver that must Be held with an adhesive to accept the torque of the real barrel nut that has male threads and threads into it..hence the red loctite on the first extension / nut.

I also made a slave pin that fit in the gas tube hole of the receiver and the extension and used it o keep it aligned and assist with taking the torque when tightening. A great system when it done.


Sent from my iPad using Tapatalk HD

93GT
12-15-2012, 12:33
Took the torch to the thing this morning and got the screws out. Took it apart and cleaned the threads up. The first nut is aligned and set with red loctite. I picked up the anti-seize this morning and found a nail that is ever so slightly bigger than the gas tube that fits snuggly to keep the outer nut lined up. I'll probably follow the recommendations above on torqing the inner nut down along with the new instructions I printed tomorrow night. JP is sending new screws to replace the ones I nearly stripped free of cost even though I was the bone head that messed up. After I get those on there, I will take it out and shoot it next weekend. Thanks for the help.

Mayhem like Me
12-17-2012, 09:17
range report when you are done...

93GT
12-17-2012, 15:07
Torqued to 70 lbs with the new Craftsman wrench I have. Recommended by JP was 50-80. Gas tube lines up perfectly, just waiting on the screws to get here and I will head to the range on Saturday or Sunday to report back. I imagine my inexperience and inability to print off another set of instructions will be the single point of failure here. I would rather be the idiot who made a mistake and has a working LR-308 than the idiot that screwed up his expensive rifle and was too proud to ask for help. I have done an inch at 200 yards on three shot groups, which proves little and an inch at 100 yards with five round groups on this rifle before I tossed a spike's NiBoron regular trigger in there instead of the DPMS factory trigger and this handguard. If I get the same thing out to 200 (not heading out to the 500 yard range this time) at this point with the longer handguard, I will be happy. I want the rifle to be accurate, but with a 3-9x scope, MOA or so out to 500-600 yards is about the best I really expect to get. Thus far my 500 yard groups are closer to 8" than 5", but that might be a lot more due to the trigger and the shooter than to do with the rifle/ammo combination. The 165 gr Accubond seems to shoot rather well out of it when I do my part.

faawrenchbndr
12-17-2012, 19:39
Great progress...........

Big Bird
12-17-2012, 20:03
Just a quick tip. Accubonds are great but very expensive bullets. You will find Ballistic tips are about half the cost and have all the accuracy of the Accubonds. I like Accubonds. Really. But I've also killed enough deer with Ballistic Tips to know that they perform awesome on medium game as well. Never had a deer survive a ballistic tip and almost always get complete pass throughs with very devastating wound channel.

93GT
02-03-2013, 14:20
200 yards, same SSA 165 grain Accubonds after I took some good advice from you guys. Just now got around to shooting it and didn't have time for anything to produce the best the rifle is capable of. Just tossed it on a set of duct tape bags, zeroed it at 100 yards and shot three rounds at 200 yards from the magazine. Thanks again for the help.