Loose mod

[siameseHague]

Hello,

I was confirming the zero on my rifle (.308) today, and since I was at the range I put another 10 rounds on paper. I'd say I fired about 15 rounds.

The mod was very loose at the end of this. I didn't see an impact on accuracy, but thought it a bit off, especially if this happened when out and about where it could work its way down the threads a bit.

Is this normal? I keep the mod off the rifle when not in use. I don't have an o-ring on the gun, and don't have any grease on the threads.

 

[timbrayford]

Normal if you don't keep it a decent hand tight, just check after every few shots with gloves on

 

[steve dunham]

I failed my dsc1 because of this, when I got home I put a dot of red nail polish on the barrel and one on the mod to give me a visual aid to know if the mod is loose.

 

[siameseHague]

So best to add to the list of things to do when lining up for a shot - check the mod is tight.

 

[HonestJohn]

So best to add to the list of things to do when lining up for a shot - check the mod is tight.

Nah

Just make sure it’s fist turn tight when you set off. If there’s any risk of it coming loose outwith sustained firing, you need to get your threads re cut to one matching the mod

 

[jb1]

When i screw mine on i screw up tight, back of slightly about 1/2 turn then give a snatch tighten so it locks on, but i check if im firing off a few down range.
Having ruined a JetZ because i had neglected to check on a LR session, it was a valuable lesson, it was a .025 on a 6.5 so not much room for any error.

 

[FlyBoy270]

I actually use a copper washer under my Mod and Muzzle brakes - you can hammer or file them to the desired thickness or use multiple to attain the correct indexing for a ported brake - assuming you have sufficient thread

 

[WalkedUp]

So best to add to the list of things to do when lining up for a shot - check the mod is tight.

It becomes habitual when you put the mod on, then periodically whilst stalking… like patting your pockets to check for your keys, you don’t even think. After a series of shots when zeroing you come back to the rifle and again subconsciously make the tiny pre-flight checks. Same as if you take a couple of shots you automatically top off the magazine when you start to walk and a shot isn’t immediately likely. I wouldn’t think about it at all when taking the shot, perhaps I’m a poor shot but the more you get the shot into autopilot the better!

 

[DMc88]

Put gun grease on the rifle threading before putting on the mod. You can never get anything as tight as needed metal to metal. It binds under less tension and once the heat expands it it's easily loosened. Grease allows it to be properly hand tight, won't loosened once hot and will prevent metal to metal galling.
If you gall the threads you won't have to worry about the moderator coming off, the gunsmith will need to chop it off.

Half pea size amount of gun grease spread equally across the threads on the rifle and a good hand tight fit. Never failed me yet. Also has anti corrosion additives to keep the metal in good nick

 

[Greenmist]

I think I read on another forum, of people using spring wave washers for loose mods

 

[kieran222]

It shouldn't come loose just carrying it about but always worth checking it periodically, I do, especially when I'm zeroing or firing off a number of shots. It just becomes habit after a while, just like checking your safety.

 

[Jagged77]

Yes mods can come loose - periodically check them when shooting strings. Usually once you’ve retightened after the barrel has heated up it usually doesn’t come loose again.

I wouldn’t personally use a washer - the thread is cut for the mod to butt straight up to the face. A bit of high temperature ceramic grease can help.

 

[Liveonce]

Is this normal? I keep the mod off the rifle when not in use. I don't have an o-ring on the gun, and don't have any grease on the threads.

no o-ring should be fitted on the rifle threads.

 

[HonestJohn]

If anything, use copper grease on the threads

 

[siameseHague]

Wouldn't that make it looser?

 

[Heym SR20]

Wouldn't that make it looser?

No. With any thread you need a good lubricant as it then allows the tension to spread across all the threads rather than just a few friction points. With no lubricant these few friction points give enough resistance to the turning torque that you think its tight.

With a lubricant that same turning torque allows the threads to be tightened so that whole thread has same level contact, as in the case of when just a few friction points have with no lubricant. Net effect is a very much level overall tension on the fixture.

Threadlock also acts as a lubricant and allows the fixture to properly torqued.

Copper slip is what is used on all the bolts around the brakes of a car. It prevents heat galling up every thing.