Mod to rifle thread tightening - advice please!

Leica Amplus 6

Zeissman

Well-Known Member
Hi all,

I have an ATec mod for the end of my Sako 75 in 308. The mod sits very well when first screwed on but after a bit of carrying in its slip or a few rounds down the barrel, it almost always works loose. Is there a product like loctite that I can use to tighten the thread up a touch? It sounds precious but the rifle is a deluxe model that I've done quite a bit of hidden accurising work to and is therefore quite difficult to replace so I'm very wary (read paranoid!) about corrosion, etc. Any suggestions very welcome!

I'm out on the hinds on Thursday and Friday and won't have a chance to re zero - what do we think? Same point of impact if I am able to increase the friction in the thread or will the mod have moved?

All best,

Z.
 

paul o'

Well-Known Member
my 2p worth.
i'v used white plumbers ptfe tape before just make sure the cut ends are to the rear and don't fall in front of the crown not a lot just once around, if its a real problem a copper crush washer thin as you can find pack cost a few bob,found ford sump ones 1/2 hole were ok on old rem years ago this was my rifle and my way of dealing with the same problem with a husher mod if you feel unsure take your set up to a smith.
 

dlz90

Well-Known Member
Hi all,

I have an ATec mod for the end of my Sako 75 in 308. The mod sits very well when first screwed on but after a bit of carrying in its slip or a few rounds down the barrel, it almost always works loose. Is there a product like loctite that I can use to tighten the thread up a touch? It sounds precious but the rifle is a deluxe model that I've done quite a bit of hidden accurising work to and is therefore quite difficult to replace so I'm very wary (read paranoid!) about corrosion, etc. Any suggestions very welcome!

I'm out on the hinds on Thursday and Friday and won't have a chance to re zero - what do we think? Same point of impact if I am able to increase the friction in the thread or will the mod have moved?

All best,

Z.



First clean the threads then apply a small amount of grease to them and tighten her up this should help the moderator fit snugly onto the barrel, and eliminates the friction that prevents the threads from getting a proper purchase..............
 

375 mag

Well-Known Member
Try all of the above none should affect zero however if the threads are cut correctly it shouldnt be working loose !
 

ejg

Well-Known Member
I think one problem is.... a M14 or 1/2" thread size should normally be tightened with a decent sized spanner to avoid opening. Just look at how tight one tightens wheel nuts. Not unusual for a thread to get loose if only tightened lightly by hand.
Another reason that leads to problems is that sometimes threads are cut with too little tolerance and sometimes the shoulders can therefore not mate up if the thread or shoulder angel are not 100% perfect. There is a reason for a small amount of play in threads. To check if the shoulders are mating properly one can use some engineers blue.

I have one rifle where everything seems wrong, barrel 16.5mm, thread m16x1 and mod thread cut way too big. Never had a problem and shoots straight out to 400m. Mod never goes loose either.
edi
 

Myford

Member
Agree with ejg , if you are concerned with too much force applied you may want to try Loctite 248 from Half*rds.

Could also check if your male thread is under cut at the shoulder, or equally the female end is recessed to take the thread shoulder. Its possible it is sitting on curve of the shoulder of the thread, could also be there is a tolerance issue, the male is at minimum and the female thread at maximum. Various loctite screw thread locking solutions are available but be careful as some set very solid and need heat to break them.
 

Zeissman

Well-Known Member
Thanks guys,

I think that you're right re tolerances at opposite ends of the spectrum. It's all supposedly 1/2" unf. Either way, my next mod will be a custom fit!

dlz, just to make sure that I've got this right, greasing actually increases the lock on the mod?

ejg, thank you as always. I'll have a look with engineers blue next weekend.

Myford, is loctite 248 relatively easy to break?

Thank you!

Z.
 

Yorric

Well-Known Member
IMHO Loctite is not a good solution & should be avoided - It's too strong for this application (even the low strength type) - sure it will stop the mod coming loose but you should take the mod off every time after using the rifle anyway. The teflon tape works as does a copper washer - I found thet my Atec Maxim came loose until I gave it a quick sharp nip up when putting it on the barrel. Now it remains there all day - but I've got into the habit of checking it is tight a couple of times whilst I'm out just to be sure.

Ian
 

dlz90

Well-Known Member
Thanks guys,

I think that you're right re tolerances at opposite ends of the spectrum. It's all supposedly 1/2" unf. Either way, my next mod will be a custom fit!

dlz, just to make sure that I've got this right, greasing actually increases the lock on the mod?

ejg, thank you as always. I'll have a look with engineers blue next weekend.

Myford, is loctite 248 relatively easy to break?

Thank you!

Z.


Exactly it's an old engineering trick and works really well it eliminates any friction which prevents complete lock of the threads hench the continuous loosing of the mod..................


Damian.
 

Cris

Well-Known Member
I always grease the thread and hand tighten. Another tip if you are worried about corrosion is to lightly grease the exterior of the barrel that is covered by an over barrel type mod. Always take off to store.
 

Zeissman

Well-Known Member
IMHO Loctite is not a good solution & should be avoided - It's too strong for this application (even the low strength type) - sure it will stop the mod coming loose but you should take the mod off every time after using the rifle anyway. The teflon tape works as does a copper washer - I found thet my Atec Maxim came loose until I gave it a quick sharp nip up when putting it on the barrel. Now it remains there all day - but I've got into the habit of checking it is tight a couple of times whilst I'm out just to be sure.

Ian

thanks Ian, it's become the last thing I check before getting into a shooting position. No bad thing, I suppose, just never had to do it for any other rifles.
 

Zeissman

Well-Known Member
Exactly it's an old engineering trick and works really well it eliminates any friction which prevents complete lock of the threads hench the continuous loosing of the mod..................


Damian.

Brilliant! I have some gun grease in the kit I have with me, so that's even better!! I'll let you know how it goes.
 

Zeissman

Well-Known Member
I always grease the thread and hand tighten. Another tip if you are worried about corrosion is to lightly grease the exterior of the barrel that is covered by an over barrel type mod. Always take off to store.

Thanks Cris,

Yes, I remove mod ASAP after shooting to prevent bore corrosion. Less worried about that part, more worried about any product applied to the thread that might trap water or corrode the metal.

Z.
 

Hornet 6

Well-Known Member
Small "O" ring sat in the thread relief cut, won't stop the mod sitting square on the shoulder.
But will provide a little bit of friction to prevent mod coming undone.

Neil. :)

PS: Unless the shoulder is not square to the thread, in which case it will always be a problem.
 

Zeissman

Well-Known Member
Small "O" ring sat in the thread relief cut, won't stop the mod sitting square on the shoulder.
But will provide a little bit of friction to prevent mod coming undone.

Neil. :)

PS: Unless the shoulder is not square to the thread, in which case it will always be a problem.

Thanks Neil,

This sounds like a good plan too. Will check shoulder angle when I get home.

Z.
 

Zeissman

Well-Known Member
First day on the hinds yesterday, guys. 7 rounds fired (3 as a check zero first thing and then two hinds and two calves in one string) and the gun grease on the thread did the trick! No loosening at all and still had excellent purchase when I unscrewed the mod. Thank you all for the advice!

All best,

Z.
 

bobjs

Well-Known Member
First day on the hinds yesterday, guys. 7 rounds fired (3 as a check zero first thing and then two hinds and two calves in one string) and the gun grease on the thread did the trick! No loosening at all and still had excellent purchase when I unscrewed the mod. Thank you all for the advice!

All best,

Z.

Nice one Z.

I am off to collect my new to me 243 and mod, so will be zeroing that and then out on the deer :)

I was going to tell you the grease trick but I was beaten to it.

regards and well done

bob.
 
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