Muzzle thread vs repeatability?

[Jamie956]

Hi all

Apologies if this has been covered before

So, a lot of people take their mod off after use, and, there are plenty of different muzzle threads out there. I was wondering if there’s a noticeable difference in zero shift when shooting long range, or any range, between courser threads and finer threads when the mod is put back on, say between 20tpi and 28tpi. Is this something that longer range shooters think about when buying new rifles or does it make no difference if the machine work is upto scratch?

Cheers

J

 

[Foxyboy43]

Hi all

Apologies if this has been covered before

So, a lot of people take their mod off after use, and, there are plenty of different muzzle threads out there. I was wondering if there’s a noticeable difference in zero shift when shooting long range, or any range, between courser threads and finer threads when the mod is put back on, say between 20tpi and 28tpi. Is this something that longer range shooters think about when buying new rifles or does it make no difference if the machine work is upto scratch?

Cheers

J

Hmmm. From a position of no knowledge whatsoever on the subject matter it is an interesting point - I assume that if the bore and moderator are concentric then thread is of no consequence but leaving aside the obvious problem of the bullet clipping the moderator which would be pretty evident, would a bullet exiting the moderator “off-centre” make any real difference?

 

[levigsp]

The thread pitch make no difference whatsoever.

 

[Strongman]

Only difference the thread pitch will make is to the tightening of the mod. Finer threads will tighten and hold better than coarse threads will. There is an argument that metric threads will have more play than imperial due to the fact metric are plating threads and have a greater clearances but I would not imagine this will have any bearing on accuracy.

 

[Stalker62]

I was wondering if there’s a noticeable difference in zero shift when shooting long range, or any range, between courser threads and finer threads when the mod is put back on, say between 20tpi and 28tpi. Is this something that longer range shooters think about when buying new rifles or does it make no difference if the machine work is upto scratch?

Well this is further down the "rabbit hole" than I ever want to go...

 

[Foxyboy43]

Well this is further down the "rabbit hole" than I ever want to go...

There is nothing like an early morning stimulus for the old grey matter, a fact well known to medical science, though it could be argued, quite reasonably, that this thread is indeed nothing like............

 

[8x57]

I would have thought that repeatability of how tightly the moderator is screwed onto the barrel would have a far greater influence. I've read that some even go so far as to scribe witness marks on moderator and barrel to ensure that the moderator is wound on to the same point every time.

The OP said "a lot of people take their mod off after use".
Perhaps it was just the unfortunate way that he worded it but I would have thought that we would all have learnt of the benefits of not storing moderators on rifles by now.

 

[Stalker62]

I would have thought that we would all have learnt of the benefits of not storing moderators on rifles by now.

I joined that club in July last year...


I have a "friend" who told his pal today that he had never cleaned, much less removed his .22 moderator from his rifle. The pal was both amazed and disappointed in equal measure.
Suffice to say, my "friend" was shamed into cleaning that moderator (for the first time in nearly twenty years) that evening.

Herewith a couple of pictures of the offending rifle and the krud which came off the baffles of the moderator.
I am very, my "friend" is rightly admonished...

Attachments​

• 
  
  
• 
  
  

 

[8x57]

Fortunately not quite so critical with .22lr Stalker1962, but sometimes fatal for the barrel with centrefires.

 

[Stalker62]

Fortunately not quite so critical with .22lr Stalker1962, but sometimes fatal for the barrel with centrefires.

In my defence (who am I kidding), this is the only calibre with which I committed this atrocious offence.

I was pleased to discover that when I dismantled the .22 moderator, cleaned and reassembled, there was no loss of accuracy.

The centre fire rifles all get their moderators taken off after each outing, and stored separately from the rifle.

 

[Ttocs]

Well, just to throw another element into the mix, I’m going to suggest that the barrel shoulder at the end of the thread is key to moderator fit; any thread will suffice as long as it’s true, concentric to the bore and well cut.
N

 

[MarinePMI]

Thread pitch has no real impact on the accuracy of the rifle.

And yes, there will usually be a shift in POI between having a suppressor on, or having it off (and using a muzzle brake instead). Either significantly alter the barrel harmonics and recoil climb of the muzzle (respectively). Typically, when using a 30 cal mod on a .224 caliber rifle or a 6.5mm caliber rifle, I am seeing about a .5 mil shift in POI with a titanium mod attached, and heavy profile barrel.

Once corrected for though, it has no real impact on accuracy, even at long range. This assumes of course that a shooter understands how to drive a rifle correctly at long range with a mod attached.

 

[badmolassesaccident]

Typically, when using a 30 cal mod on a .224 caliber rifle or a 6.5mm caliber rifle, I am seeing about a .5 mil shift in POI with a titanium mod attached.

How have you found using a .30 mod on a 6.5mm? Is the noise reduction much different compared with just using a 6.5mm mod?

I have the .30 mod and a 6.5 rifle, but they haven’t said hello yet, mainly due to laziness on my part.

 

[MarinePMI]

I only have a .30 cal mod, so can't really compare it against a 6.5 specific mod. That being said, I think the better question is: Why do so many just use a .30 cal can on centerfire rifles from .224 to .30 cal?

The difference in having a specific caliber mod is largely miniscule, and not discernible by shooter or game. On paper, yes there is a difference. But for all practical purposes, a .30cal mod works well enough across many calibers (especially if magnum pressure rated).

 

[Foxyboy43]

How have you found using a .30 mod on a 6.5mm? Is the noise reduction much different compared with just using a 6.5mm mod?

I have the .30 mod and a 6.5 rifle, but they haven’t said hello yet, mainly due to laziness on my part.

I use a .308 Utra on my .308 and 6.5x55. Of the two the 6.5 is definitely quieter but it is shooting 2gns less powder.

 

[jb1]

The question has to be asked
"why would the thread make any difference"

Would it make any difference with the mod off whatever thread it was, even without a thread it make no difference.

Next the questions got be asked.

will it improve my shooting if i wear my baseball cap the wrong way round.

Now there's a point

 

[MarinePMI]

Next the questions got be asked.

will it improve my shooting if i wear my baseball cap the wrong way round.

Well duh. Of course it does...

 

[Klenchblaize]

I only have a .30 cal mod, so can't really compare it against a 6.5 specific mod. That being said, I think the better question is: Why do so many just use a .30 cal can on centerfire rifles from .224 to .30 cal?

The difference in having a specific caliber mod is largely miniscule, and not discernible by shooter or game. On paper, yes there is a difference. But for all practical purposes, a .30cal mod works well enough across many calibers (especially if magnum pressure rated).

That’s very interesting and potentially a big cost saver! But only if you remember to specify use of a single (largest diameter) moderator on all licensed rifles you wish to use with said noise reduction unit.

K

 

[MarinePMI]

That’s very interesting and potentially a big cost saver! But only if you remember to specify use of a single (largest diameter) moderator on all licensed rifles you wish to use with said noise reduction unit.

K

Ah, I see there is an implied regulation I wasn't aware of. Here the can/mod is indepent of the rifles (since officially, the US government is not allowed to maintain records of who owns what after 7 years), so which rifle it is used on here is irrelevant.

Still, that is interesting. Is there any logical reason why UK shooters have to list which mod is to be used on which rifle? Seems pointless over regulation to me.

 

[Foxyboy43]

Ah, I see there is an implied regulation I wasn't aware of. Here the can/mod is indepent of the rifles (since officially, the US government is not allowed to maintain records of who owns what after 7 years), so which rifle it is used on here is irrelevant.

Still, that is interesting. Is there any logical reason why UK shooters have to list which mod is to be used on which rifle? Seems pointless over regulation to me.

It gets worse, my friend has a number of moddies, all without maker’s name or any means of identification yet his FAC specifies certain mods can only be used on certain rifles! Wot? Hows that then??