AR buffer tube nut questions?

[Grayfox54]

My brand new M&P-15 has a problem with the buffer tube castle nut coming loose. So far its happened twice, but I caught it before things fell apart. Looks like I need to get a castle nut wrench and tighten it down properly. I've done a little on line research, but have a couple of questions.

1. Torque or just tighten? I've seen recommendations for both. Some say it must be torqued while others say just get it good and tight. 

2. Foot pounds or inch pounds? I've seen the specs at 40 Ft/lbs AND 40 in/lbs. 40 Ft/lbs seems a bit heavy on a piece of aluminum to me. I sure don't want to damage the threads. But, I'm new to ARs and don't know. 

3. Stake or loctite? I've seen recommendations for both. BTW: the problem seems to be that the nut wasn't staked well enough at the factory. Only a very light dimple there. 

4.. Anybody know a store in the Memphis area that stocks the castle nut wrench? I just don't want to have to wait a week or pay shipping to get a fairly inexpensive tool. 

[rugerla1]

You can snug it up by feel if you’re staking it. If it properly staked it isn’t going to back off anymore. I imagine there is an Academy Sports there in Memphis and I know they carry them. But I’m sure Bass Pro has one as well. I wouldn’t loctite the castle nut since the staking will do the job. I use to use a center punch but have used a spring punch for past several years and about 20-25 clicks and the staking is complete. 

[mikegideon]

Stake it! 

[Grayfox54]

I found the tool at Bass Pro. They were closer and I had a little money left on a gift card. So no out of pocket expense. 

The nut is now properly tightened and staked. 

Thanks. 

[rugerla1]

51 minutes ago, Grayfox54 said:

I found the tool at Bass Pro. They were closer and I had a little money left on a gift card. So no out of pocket expense. 

The nut is now properly tightened and staked. 

Thanks. 

Good deal!