Mod coming loose

NickJ

Well-Known Member
I bought a lightweight roedale titanium mod which I love but - after a few (2,3..)shots it comes loose and affects the point of impact. On a target one can, of course tighten it up but that means a position change and, of course would be no good on a herd of hinds/calves.
I never had the problem with PES or T8s.
Someone suggested using PTFE tape, anyone tried that or any other ideas?
Thanks
Nick
 
Sounds to me that it may just be incompatable threads? Are you sure that the thread on the rifle matchs the thread on the moderator properly. Is it a factory cut thread on the rifle or has the thread been cut by a "gunsmith"?
 
Mmm..factory cut on a new sako 85 stainless 6.5x55 so I assumed would be OK.
 
Use a small amount of copper grease on the threads then tighten it up, assuming everything else is ok this should do the trick.


I say copper grease but any good quality grease should work.
 
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Thats the trouble sometimes a smith can cut a perfect say.... m14x1 thread and when he gets you a mod in from importers
Some of the threads in the mods are never perfect.

Have you cleaned the thread on rifle and mod ? Because sometimes this can make the mod come loose easy.
I wouldnt want to use the pte tape myself. You shouldnt have to.

When you thread the mod on the rifle half way is there alot of play in the tread
 
Mmm..factory cut on a new sako 85 stainless 6.5x55 so I assumed would be OK.

I would say that the fault probably lies with the moderator then. I have a Sako 85 with the same thread and I don't have any problems with mine and my mod of another make.
 
I`d bet the mod thread has not be cut correctly or its been crossed at some point , get a gunsmith to get his thread gauges on your barrel to confirm that .
 
Try a thin 'O' ring which is a tight fit over the threads. This should nestle on the shoulder at the base of the screwcutting. Put the mod on and off a few times, each time tightening it down hard. This should form a tight, very thin cushion which prevents the moderator working loose. I have done this with mine and zero never shifts.
 
I've been shooting with someone who thought a mod should only be tightened "light finger tight", how tight did you put the mod on?
Is the rifle bedded? Makes a very slight difference if the twist of the barrel torques the rifle towards "mod opening" direction upon firing.
Of course threads must be sound and shoulder 100% in contact with mod.
edi
 
my 85 with a t8 comes lose as well after a few shots i just used dental floss, just at the shoulder seemed to solve it gives it a bit of friction to grab on too

ps rifle is davcon beded and floated
 
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ejg - Factory bedded sako 85. I usually screw it on as tight as I can.

All - I took it on the range on Sat and actually it was only the 7th shot that it came loose. I tried some grease (Bisley grease I use on the bolt) and after another 7 it was a lot better so happy with that. I think I've only ever once taken seven hinds/calves from a single herd. When next on a range day I might try the dental floss trick though Paul, I guess it's very similar make-up to PTFE tape.

Thanks
 
Try a thin 'O' ring which is a tight fit over the threads. This should nestle on the shoulder at the base of the screwcutting. Put the mod on and off a few times, each time tightening it down hard. This should form a tight, very thin cushion which prevents the moderator working loose. I have done this with mine and zero never shifts.

+1 rubber o ring is a good way to go.
 
I would not go with an O ring or tape the thread , both are a bodge , better to get it fixed professionally , the OP is talking about a centrefire not an air rifle, continuous tightening a damaged thread will cause eventually to completely fail , you may end up shooting your quarry with a mod rather than a bullet !:doh:
 
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As I have said before why do the people threading these items use the proper gauges?

You mean why DON'T they use the proper gauges? Well I think it is as much to do with gauges as it is with understanding thread dimensions, tolerance classification and how to measure a thread.

Although in this case I am not convinced it's a thread problem. A thread which is tight does not become loose because the thread is out of spec. If the mod is tightened by hand to say 8NM, then it'll take 8/9NM to free it.

PTFE tape will do no harm. It can take heat and lubricates the thread upon removal. Not sure it'll do any good either. Might pack the thread and prevent a nut rattling loose, but wont stop the torque reaction applied to the thread from the rifling direction.
 
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