Loctite Strength

[sammass]

Applied 'reasonable' torque to the clamp-on muzzle break screws (3/32 hex head) and all four were loose after 30 rds of .308. Still want the break to be removable, but would prefer it to stay in place until removed by me.

For fine threaded (SAE 40) screws, is there a strength of Loctite that is preferred? Ball park torque?

Thanks in advance.

[jericho89]

I do not know torque specs, but blue is used for items that you want to remove in the future and red is used for those items that you do not want to remove unless you really have to.

[kcstott]

Color is not the way you grade loctite.

There are three to four different grades and applications for each color.

Most "blue" is medium strength.

loctite 222 is low strength but will prevent screws from backing out.

there is no torque spec that I know of for what loctite will hold back.

[jimmykan]

Sammass, for muzzle devices, I recommend using Rocksett.

Flexbar Rocksett High Temperature Thread Locking Compound 2 oz

It has the locking strength of Blue Loctite (242 or 243), so its removable with just hand tools, yet it retains its locking strength up to 2000*F.

[sammass]

Fellas, Thanks much for the advice. Will look into Rocksett for next application, but have some Blue 242 on hand, so that's the first option.

Regarding the screw torque, was just asking what a reasonable range might be for that fine thread screw, not considering Loctite. I'm sure some folks might consider a 12" cheater the minimum requirement. :-) I'll use ~12# after everything is snugged in with the wet Loctite. Find out tomorrow @ the range.

Thanks again. :-)

[Garv]

Jericho has it down.
Blue is cool, Red makes your threads essentially permalocked.

Mil-S-46163 is an older military spec. (everyspec.com) that has relative torque values for Loctite.
Specific bolt/nut materials and sizes are used.
Numbers in real use will be different based on several variables.

Blue (242) is Type II Grade N.

The currently active ASTM D5363 is a pay per view spec.

Make sure your threads are clean and dry before applying.

[Librarian]

See also http://www.henkelna.com/us/content_d...ide_032010.pdf

[sammass]

Henkelna has The site for the details. If I had had some purple would have used it, but not the normal HD stuff I had on hand. Minimized the volume on the threads. Thanks for the references. :-)

[kcstott]

If you want to know typical and maximum torque values you need to know the size of the screw. Hex head size on anything gun related tell you nothing at to the size of the threads

[ar15barrels]

Applied 'reasonable' torque to the clamp-on muzzle break screws (3/32 hex head) and all four were loose after 30 rds of .308. Still want the break to be removable, but would prefer it to stay in place until removed by me.

For fine threaded (SAE 40) screws, is there a strength of Loctite that is preferred? Ball park torque?

What EXACT muzzle device are you using?

Is it one of those ones with set screws that clamp against the barrel?
Those rarely stay tight on the barrel because the set screws will DIG INTO the barrel during barrel vibration.
The actusl screws are NOT turning loose.
The BARREL is getting dug into during vibration.
No type of thread locking compound will cure this problem.