Trouble .POI shift removing MOD.

[Mash67]

Ok I have been having a bit of a problem with my rifle and moderator.

 

I was advised to take the mod of after each outing to stop it welding to the rifle and ruining the crown. Which I haven’t been doing because their both stainless and didn’t think I needed too.

The barrel and mod are 3 years old and apart from cleaning every 4 months or so never come apart

 

The barrel has shot over 1000rnds and can still shoot 3 shot touching at 200 and 11/4 at 500 if all goes well. So same as when new

 

If cleaned it takes 10 or more rounds to start tightly grouping again and I probably then shoot at least 100 before cleaning again. I think that the rifle likes the mod to be on really tight which happens with the firing of the gun, it really locks it on, so all good

 

But as soon as I start putting it on and of POI starts changing and slowly comes back to where it was before or near, this is a real pain, and also means as it’s my deer rifle that it’s unacceptable as I can’t have a different zero 8 to 10 times a week when I’m out culling

 

, i’m tempted to go back to leaving it on all the time again between cleaning.

Or find some way of really winding it on tight.

 

Any suggestions

 

Thanks Matt

[happyhunter]

I clean my foxing rifles after every outing and the mod only goes on when the rifle comes out with a touch of anti seize compound on the threads and never had poi shift. I wonder if it's nothing to do with your mod and more that your rifle likes a bit of carbon build up in the throat/start of the rifling to get it on song? What rifle, load etc are you using? Simon

[Mash67]

I clean my foxing rifles after every outing and the mod only goes on when the rifle comes out with a touch of anti seize compound on the threads and never had poi shift. I wonder if it's nothing to do with your mod and more that your rifle likes a bit of carbon build up in the throat/start of the rifling to get it on song? What rifle, load etc are you using? Simon

hi

243 using varget with 95g smk, but the guns already dirty when i take the mod off, trying this new to me on and off daily method.

[gun nut]

Friend of mine had a similar problem, after much faffing about turned out to be a front action screw that wasn't as tight as it should be.It was the torquing on and off of the mod was moving the action in the stock and altering the harmonics. First couple of shots were wild then it settled down to somewhere close to its first poi. Worth a look before you explore more drastic solutions or worse, loose faith in your deer stick!

 

atb

 

Mike

[Mash67]

Friend of mine had a similar problem, after much faffing about turned out to be a front action screw that wasn't as tight as it should be.It was the torquing on and off of the mod was moving the action in the stock and altering the harmonics. First couple of shots were wild then it settled down to somewhere close to its first poi. Worth a look before you explore more drastic solutions or worse, loose faith in your deer stick!

 

atb

 

Mike

thanks.i'll look at this also

[Lee]

Matt,

 

don't be fooled by someone telling you that the stainless barrel is corrosion free, it would be if it were pure stainless but it's not. The stainless steel grade will more than likely be 416 so it is machinable which still has a lot of iron in the steel but has rust resiting properties with the added sulphur.

 

The barrel will corrode much less than a traditional style Chrome Molly steel barrel En19-En24, but you still need a little oily rag wipe down where the acids from your fingers/sweat and rain have been. Most importantly you need to remove the mod so you can clean the crown and oil the thread, otherwise the powder fouling deposits will collect at your muzzle and mix with condensation or other moisture and slowly but surly eat away your crown leading to grouping problems and will need to be re crowned or even re threaded in the future.

 

Now obviously the barrel will shoot different with mod on and mod off, which mainly affects sporter barrels more so but if your moderator is the type that has a plastic bush at the back, check that this is not too tight.

In my 12+ years in the trade I discovered very early on when the reflex design moderators came on the market that this has always been one of the main reasons why rifles change impact after zeroing with it on, removing the silencer, re mounting the silencer and finding it shoots in a different place again.

 

There is no need for this bush to be tight, it's only use is to stop the moderator from lopping to one side should it undo it self a few turns.

 

ignore all above if you have a forward mounted silencer.

 

atb Lee

[Mash67]

Matt,

 

don't be fooled by someone telling you that the stainless barrel is corrosion free, it would be if it were pure stainless but it's not. The stainless steel grade will more than likely be 416 so it is machinable which still has a lot of iron in the steel but has rust resiting properties with the added sulphur.

 

The barrel will corrode much less than a traditional style Chrome Molly steel barrel En19-En24, but you still need a little oily rag wipe down where the acids from your fingers/sweat and rain have been. Most importantly you need to remove the mod so you can clean the crown and oil the thread, otherwise the powder fouling deposits will collect at your muzzle and mix with condensation or other moisture and slowly but surly eat away your crown leading to grouping problems and will need to be re crowned or even re threaded in the future.

 

Now obviously the barrel will shoot different with mod on and mod off, which mainly affects sporter barrels more so but if your moderator is the type that has a plastic bush at the back, check that this is not too tight.

In my 12+ years in the trade I discovered very early on when the reflex design moderators came on the market that this has always been one of the main reasons why rifles change impact after zeroing with it on, removing the silencer, re mounting the silencer and finding it shoots in a different place again.

 

There is no need for this bush to be tight, it's only use is to stop the moderator from lopping to one side should it undo it self a few turns.

 

ignore all above if you have a forward mounted silencer.

 

atb Lee

hi

yeah i was told that stainless would eventualy corrode which is why i wanted to do the right thing and remove the mod, but with change in POI this wasnt working.but maybe the barrel harmonics want the mod put on realy tight,just a thought.the POI does creep back after a number of shots but this is unacceptable for regular removal.i will have to experiment a bit i think and try to pin point the problem

thanks

Matt

[baldie]

Make sure there is at least 10 thou clearance on the rear bush. It should not be touching at all. Its not there to align the moderator, but as a safety device if the mod comes loose a turn or two.

 

If the shoulder on the thread has been cut correctly, the mod should spin down the thread, and snap solid against the shoulder. This is a sure sign the shoulder is absolutely square, and you should then have to give the mod a good wrench to free it. If you have to tighten the mod onto the thread, and then the shoulder, the threads are not to spec and too tight.The mod should freely spin down them, and be free to align itself on the shoulder.

Back the mod off a full turn, then waggle the mod from side to side. There should be half to one mil waggle from centre if the thread is to spec. If it wont waggle, its too tight.

 

Ths critical part of a moderator thread, is a square shoulder.

[Chris-NZ]

As Matt said, "stainless" is really only corrosion-resistant.

 

Here's my brother's T3 that has lived in Fiordland (read: often wet). I stripped it down to have a can fitted and here's what I found

 

 

He'd kept the visible bits well oiled but hadn't even thought about what you can't see. The gun assembled looks largely mint.

 

I'm about to reassemble it and will give the covered-up bits a spray with CRC "Soft Seal". It's a fancier corrosion protection spray that sets a film on the metal surface. A engineeering guy who seemed to know his stuff recommended it so well worth a try. According to the info on the can, "it's an aliphatic wax-based protective coating ..provides long-term protection ... highly resistant to humidity, salt water and salt spray. .. will never become brittle.."

 

Chris-NZ

[Mash67]

Make sure there is at least 10 thou clearance on the rear bush. It should not be touching at all. Its not there to align the moderator, but as a safety device if the mod comes loose a turn or two.

 

If the shoulder on the thread has been cut correctly, the mod should spin down the thread, and snap solid against the shoulder. This is a sure sign the shoulder is absolutely square, and you should then have to give the mod a good wrench to free it. If you have to tighten the mod onto the thread, and then the shoulder, the threads are not to spec and too tight.The mod should freely spin down them, and be free to align itself on the shoulder.

Back the mod off a full turn, then waggle the mod from side to side. There should be half to one mil waggle from centre if the thread is to spec. If it wont waggle, its too tight.

 

Ths critical part of a moderator thread, is a square shoulder.

i'll look into this

 

what do you think about really tightening the mod on,rather than just a bit tight.i normaly screw it on till it stops then give it just a tweak more,but when i take it of after a lot of shooting its really tight to take of,should i try to emulate this tightness when putting it on to get some sort of continuity

[Mash67]

Make sure there is at least 10 thou clearance on the rear bush. It should not be touching at all. Its not there to align the moderator, but as a safety device if the mod comes loose a turn or two.

 

If the shoulder on the thread has been cut correctly, the mod should spin down the thread, and snap solid against the shoulder. This is a sure sign the shoulder is absolutely square, and you should then have to give the mod a good wrench to free it. If you have to tighten the mod onto the thread, and then the shoulder, the threads are not to spec and too tight.The mod should freely spin down them, and be free to align itself on the shoulder.

Back the mod off a full turn, then waggle the mod from side to side. There should be half to one mil waggle from centre if the thread is to spec. If it wont waggle, its too tight.

 

Ths critical part of a moderator thread, is a square shoulder.

i'll look into this

 

what do you think about really tightening the mod on,rather than just a bit tight.i normaly screw it on till it stops then give it just a tweak more,but when i take it of after a lot of shooting its really tight to take of,should i try to emulate this tightness when putting it on to get some sort of continuity

[Hatzi]

Sounds to me more like the action is shifting slightly in the stock. Id suspect a bedding issue or lack of it as the OP says it returns to zero after a few shots which most likely shuffling the action back to its natural resting position in the stock.

[Mash67]

Sounds to me more like the action is shifting slightly in the stock. Id suspect a bedding issue or lack of it as the OP says it returns to zero after a few shots which most likely shuffling the action back to its natural resting position in the stock.

i can look at this but it has to have a bearing in this situation between removal and replacement of the mod, this is when the POI shifts

[Hatzi]

Exactly, you are are twisting your mod on and off the barrel and whether tight or slack, you are still tweaking your action with a 22-24-26"? lever as well as applying rotational torque as it locks up to or comes away from the barrel shoulder.

[Mash67]

Exactly, you are are twisting your mod on and off the barrel and whether tight or slack, you are still tweaking your action with a 22-24-26"? lever as well as applying rotational torque as it locks up to or comes away from the barrel shoulder.

i see your point.i'll check my bolts

thanks Matt