On Midway's site it is claimed that 609 will fill in up to a .005" gap and 620 up to .015" gap. If the fit is tight there is no gap to fill.
A new barrel nut will not eliminate the slop between extension and receiver.
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On Midway's site it is claimed that 609 will fill in up to a .005" gap and 620 up to .015" gap. If the fit is tight there is no gap to fill.
A new barrel nut will not eliminate the slop between extension and receiver.
Last edited by mpom; 01-21-14 at 16:00.
Thanks for the suggestion. Will do (along with 10 shots per).
I did not know this. Thanks! It's actually a different barrel nut. The old rifle had old-school handguards on it, and this one has LaRue free-float rails. I have emailed LaRue to ask about reusage of this nut and will update with their answer as soon as I have it.
From watching videos of barrel installations, it looks like there should be a tighter fit than what I have between barrel extension and receiver. I'm hoping a new upper will fix this. Would like to avoid putting anything but moly-grease in there, but I will definitely keep this in mind. Thanks.
I need to take a couple weeks to get moved across the country and will update with new information as soon as I get it. I really appreciate all the help and advice here. It's worth a million dollars.
To-do:
* update with LaRue's answer about reusing the barrel nut on LT15-7
* update with any notes about felt differences re fit between DPMS upper vs BCM upper with DD barrel
* replace upper with BCM and re-try with 10 shot groups without muzzle device
* swap upper group to rifle's lower and make some more 10 shot groups; compare.
From Dan at LaRue: "As long as the barrel nut is not damaged, you can re-use it."
A pleasure.
This only speaks for the barrel nut as packaged with the LT15 series of LaRue handguards. In quick further research, I found a few forum posts stating it was fine to reuse standard barrel nuts as long as the threads aren't damaged and it has enough teeth to torque it to spec.
Varminting or target ARs may well have different expectations.
“The rifle itself has no moral stature, since it has no will of its own. Naturally, it may be used by evil men for evil purposes, but there are more good men than evil, and while the latter cannot be persuaded to the path of righteousness by propaganda, they can certainly be corrected by good men with rifles." - John Dean "Jeff" Cooper, The Art of the Rifle
I've used green Loctite to install new bearing in the rod ends for the control surfaces of different aircraft, There's a big difference between how much gap they claim can be filled and how much gap it fills in actual use. A special primer is also used before applying the green Loctite. If there is a gap, the Loctite does nothing to hold the part in place. Green Loctite does help hold parts in place when there is a close slip fit or a press fit. Even with polished surfaces, there are peaks & valleys. You may not be able to see them without a microscope, but they are there. When the two parts or fitted together, they only make contact on the peaks. Using adhesive filles in the valleys increasing the grip.
None of this is to suggest that green Loctite should be used when installing a barrel to an upper. It will make removing the barrel more difficult. Of course, this doesn't matter if you plan to get a new upper when swapping barrels
KF5MLT, KD6IJG
INSIDE PLAN OF BOX
- ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
- MATCH SCRATCHES ON MATCH-BOX
- MATCH LIGHTS FUSE TO TNT
- BOOM!
- HA-HA!!
-WILE E. COYOTE, AUTHOR OF "EVERYTHING I NEEDED TO KNOW IN LIFE, I LEARNED FROM GOLDBERG & MURPHY"
I am American
thanks for the info, never too proud or old to learn.
sounds like green loctite is for a more or less permanent application, not a good choice for an ar barrel.
Thanks for all the help. The upper receiver was swapped out for one from BCM and that seems to have fixed everything up. (The SSA is the 77 gr. OTM variety.)
IMG_20140209_164644794.jpgIMG_20140209_164656398_HDR.jpgIMG_20140209_164806311.jpgIMG_20140209_164758269.jpg
Yes, I would have gone nuts if I had to wait another week to get out and test this thing.![]()
Glad swapping the receivers worked out for you, next time this should help you steer away ==> D.P.M.S. = Don't Purchase Monkey Shit
“The rifle itself has no moral stature, since it has no will of its own. Naturally, it may be used by evil men for evil purposes, but there are more good men than evil, and while the latter cannot be persuaded to the path of righteousness by propaganda, they can certainly be corrected by good men with rifles." - John Dean "Jeff" Cooper, The Art of the Rifle
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