Spray back from moderator

[squatman86]

Hi there,

I'm using a Tikka T3 .308 Varmint with a Riflecraft Hardy GEN IV Moderator.

When firing with the moderator on I get a blast of air back at me the shooter sometimes with bits fired back at me, this is also making a mess of my scope.

Is this normal? I'm target shooting so perhaps shooting off more than if I was stalking, so I need to clean the mod and/or barrel exterior between a certain amount of shots? Or is there something wrong here?

Any thoughts, advice or suggestions would be appreciated.

Thank you.

[banus02]

too little information to work with.

[Re-Pete]

I'd say there was something VERY wrong......

Odd that there's no mention of such an animal on the Riflecraft website, though, are you sure it's made by them?

Pete

[Catch-22]

Do you also get excessive smoke & unburnt powder without the mod on? Are your cases coming out of the chamber with very sooty necks/shoulder/body?

Of so, it could be that your load isn’t generating enough pressure (due to incorrect powder or a low charge weight).

Alternatively, what’s the barrel to mod fit like? Do you use a brake or attachment between moddy and barrel. Is that on tight?

Are you 100% the mod threads match the barrel/brake threads?

If it’s an ‘over barrel’ design of moddy (most of the mod goes over the length of the barrel like a sleeve), what’s the bushing like at the end, which is meant to sort of ‘seal’ the rearward portion of the moddy around the barrel. If the bushing is poorly fitted, or too thin a barrel used in a wide opening, or no bushing exists then excess gas could leak between rear bushing and barrel  - thus coming back at you.

Are you regularly checking the moddy isn’t coming loose during firing? As the metal expands and contracts, things can loosen a bit and allows excess gas to escape.

^^ just a few possible causes of your symptoms. More info about your setup and experience with and without the mod may help.

Regarding cleaning, you definitely need to clean off the carbon around your barrel/mod threads and mounting surfaces. Not only will carbon build up lead to corrosion, it’ll ‘bake’ the moddy onto the barrel and make it a bugger to remove. After cleaning the threads, add some anti seize paste (I actually use a high temp ceramic paste) to aid easy removal of the mod after a long shooting session.

[Richiew]

Peter Moore did a review of this in 2016 so it’s a genuine piece of gear . 
check threads and mating surfaces to be clean and flat to each other , otherwise there’s maybe a hole in the part that comes back over the barrel. The reviews say it’s not strippable so it may have come to the end of its lifespan. Get it checked out by a gunsmith?? . Don’t want it to explode. 

[banus02]

first question, do you home load? 2nd question are your reloads worked up from the start load and stop before the maximum load? so many variables. you could be about to lose your eye sight/hearing or worse!!!!!. seek professional help!

[Roy W]

The OP has also asked on Fullbore UK and received lots of opinions. He posted photos on there plus more info , factory ammo, Mod he has had for 5 years and possibly 1 year old when he got it. 

I doubt he'll be back, might be worth waiting for him to post more before trying to fathom it out.

 

HERE:

[squatman86]

Thank you all for your time and responses.

@Re-Pete - yes it's definitely that moderator, as @Richiew confirm but I shall also attach photos.

@Richiew - I do my best to clean the moderator but not easy to get in down to the threads, I spray action blaster and Napier rapid degreaser in there, I've tried twisting a rag in too. As far as I can tell they are flat to each other, it feels quite a smooth and solid motion when twisting into place. If we don't find anything definitive, I'll get a gunsmith to check the moderator for gaps.

@Catch-22 -

No excessive smoke without mod, where would the unburnt powder be? I'm using factory ammo, case come fine as far as I can tell (see attached photo of cases from Sunday)

The fit seems smooth and solid, no brake or attachment between. Is this also referred to as a rear bush? Is this something I need?

Moderator has M18x1.0 printed on it, and from what I've found online Tikka T3 are 14x1 for Light Barrels and 18x1 for Varmint.

It is over barrel (see attached photos) I don't know if there is any bushing? It's hard to see in the moderator and it cannot be dismantled, I've attached photos to hopefully help. There is about a 1.5-2mm gap between the barrel exterior and the moderator interior (for the part "sleeving" the barrel).

I do find myself seeing if I can twist the moderator after several shots, but it never moves and takes quite a bit of force to unscrew after use (I have no experience with other moderators, this may be normal)

Thank you very much for all your questions and suggestions, you'll see in some of the photos the embarrassing state of the barrel, I definitely learnt the hard way, and now ensure my guns and equipment are cleaned. As stated the moderator is difficult to inspect in detail, I've heard people mention using ultrasonic cleaning baths. Maybe this would be of use.

If I haven't answered right or provided enough detail please let me know.

Thanks again.

[Richiew]

Yep seen the other post and photos. Barrel edge looks well pitted . Threads don not make the seal . Sealing surfaces are the edge inside the mod and the back part of the barrel after the undercut of the threads . If any of these is a poor fit gas can pass along the threads and escape . Try coppa slip on the barrel threads and you should be able to see copper grease blown down the barrel if that’s where the problem is . 

[squatman86]

@banus02 - no I use factory ammo

@Row W - thank you for jumping in, I had responses on that forum a bit sooner so ended up replying there as and when. I'm not a member of any shooting forums so I wasn't sure which would be more active hence posting on both. Thanks for replying and linking the other thread.

[squatman86]

2 minutes ago, Richiew said:

Yep seen the other post and photos. Barrel edge looks well pitted . Threads don not make the seal . Sealing surfaces are the edge inside the mod and the back part of the barrel after the undercut of the threads . If any of these is a poor fit gas can pass along the threads and escape . Try coppa slip on the barrel threads and you should be able to see copper grease blown down the barrel if that’s where the problem is . 

@Richiew - thanks again. Is the copper slip just a method to prove this is where the problem is? Is there any specific copper slip I should get, how do I know the size I would need?

Cheers.

[squatman86]

Oh is it a grease?

[Richiew]

Your cases look fine . Don’t think you’ll need a bushing with a big fat thread of 18x1 . That pitting might be gases cutting the edge hinting that there’s a problem inside the mod . Any of your mates got a mod with same threads you could try to eliminate the problem?? 

[Richiew]

Copper slip is a grease . Halfords will have something similar. It’ll stay coppery colour for the first shot . So put it on the barrel threads and shoot once then take off the mod and if there’s copper colour grease splatted down the barrel it must be coming through the threads . If no grease but still gases blown back then you’ve got a hole in the mod ?? . What about plumbers thread tape on the threads just to rule out poor threads??

[Richiew]

Looking at your photos down the end of the mod . There looks to be a gap between the silver thread adapter anthe edge of internal bit of the alloy over barrel part . Looking at Hardys manufacturing video  the baffle stack screws into the outer tube so there must be either an o ring or metal to metal seal in there somewhere, so if there’s a leak here this might be why your barrel threads are ok but the edge of the barrel is pitted from hot gases cutting the metal . Send it back or get something newer . 
 

The nice lady at wildcat mods asked about my rifle model and suggested a mod length that would give max sound moderation whilst not being too long to foul up on the front of the stock . 
 

Happy fault finding 

[squatman86]

@Richiew can't thank you enough for you time and responses.

I was going to try the tape around the thread and pitted area, but now you mention there may be a gap I wonder if I should get a new mod, or maybe my barrel is too far gone anyway and may only get worse... I doubt I'd be able to send the mod back, it came as a used package with the rifle, unless Hardy have a long warranty on their mods?

Thanks again, really appreciate it.

[Richiew]

Glad to help mate . Try shooting without the mod if all s good the barrel is ok . Sealing area looks good so a new mod with a brand new square edge will be sealing correctly. Good luck 

[Catch-22]

From the photos, it suggests to me like there’s a rear bushing end cap or something which is missing from the moddy. You can see the threads at the back for it. A bushing end cap is there to ‘seal’ the moddy around your barrel. Without it, you can see a huge gap between the moddy and the barrel. I think that’s why you are getting gas blow back.

But the point about the end of the barrel shoulder, where it mates to the moddy internals is well and truly corroded. This is why moddys need to be removed and the barrel cleaned after use and not stored with the moddy in place.

It is unclear if the corrosion there is as a result of gas leak (due to poor mating surfaces, poor thread alignment or just due to leaving moddy attached and stored for long periods of time. Regardless, it doesn’t look great.

Personally I’d chuck the moddy and get a new one at the same time as having the muzzle, crown and threads checked over. The barrel threads and shoulder could be the problem and not the mod, so best get them checked before investing in a new mod.

[squatman86]

Yes after closer inspection it looks like the shoulder is heavily corroded/pitted (see attached photo). I think I may have found some pitting or fouling at the end of the bore as well.

Without the moderator I have no issues @Richiew .

Do you guys have a recommendation for a decent moderator please? I only do target shooting if that makes a difference.

Also any idea how much muzzle, crowning and threading works cost?

Thank you all once again, much appreciated.

[Richiew]

27 minutes ago, Catch-22 said:

From the photos, it suggests to me like there’s a rear bushing end cap or something which is missing from the moddy. You can see the threads at the back for it. A bushing end cap is there to ‘seal’ the moddy around your barrel. Without it, you can see a huge gap between the moddy and the barrel. I think that’s why you are getting gas blow back.

But the point about the end of the barrel shoulder, where it mates to the moddy internals is well and truly corroded. This is why moddys need to be removed and the barrel cleaned after use and not stored with the moddy in place.

It is unclear if the corrosion there is as a result of gas leak (due to poor mating surfaces, poor thread alignment or just due to leaving moddy attached and stored for long periods of time. Regardless, it doesn’t look great.

Personally I’d chuck the moddy and get a new one at the same time as having the muzzle, crown and threads checked over. The barrel threads and shoulder could be the problem and not the mod, so best get them checked before investing in a new mod.

The rear bushes are mainly for alignment purposes, MAE do a bush less  design so it’s not there for sealing purposes. My wildcat predator design has a bushing but it has slots in it so no seal . A plastic bush is not going to stop thousands of psi from escaping but metal to metal or o rings will . 
cheers

[Catch-22]

9 hours ago, Richiew said:

The rear bushes are mainly for alignment purposes, MAE do a bush less  design so it’s not there for sealing purposes. My wildcat predator design has a bushing but it has slots in it so no seal . A plastic bush is not going to stop thousands of psi from escaping but metal to metal or o rings will . 
cheers

Thanks. Yes I myself have a MAE bushless on my AI AWM.

I wasn’t implying the rear bushing itself stops back pressure, but from moddy designs I’ve used in the past, the rear end cap bushing did incorporate a series of o rings within it - thus serving both as alignment AND effectively sealing the mod over the barrel to prevent back gassing. To me it looks like the OPs mod is missing this part.

[Triffid]

I agree with Catch-22, there should be a bushing at the rear of the moderator to seal the gap between the moderator and the barrel. The ones on Wildcat moderators are machined out of dieldrin and I've got a couple to fit different barrels - see picture.

With Wildcat, I just had to tell then the diameter of the barrel at the right point and they machines one up for me. Perhaps Riflecraft can do the same?

Triffid

[Kalahari]

I am sure the Delrin washer isn't there to catch hot gas. The mod shouldn't be leaking gas backwards. I think as previously stated it needs checking and possible replacing.

 

David.

[Catch-22]

2 hours ago, Kalahari said:

I am sure the Delrin washer isn't there to catch hot gas. The mod shouldn't be leaking gas backwards. I think as previously stated it needs checking and possible replacing.

 

David.

That’s not true.

The whole point of the ‘reflex’ moderator design is so that gas is leaked backwards over the barrel. It’s is one of the moderators expansion chambers and is designed to accept gas and allow it to swirl around before dissipating, thus reducing the rapport of the shot.

End of muzzle moddys have all of the expansion chamber(s) ahead of the muzzle.

I believe the OPs moddy is missing the end cap, which is meant to seal the over barrel expansion chamber and prevent gas leak backwards. Without this cap, this is why they’re getting back blast and bits of unburnt powder and residue all over their scope and in the eyes.
And the corrosion of the barrel is a huge downside to reflex type moddys. But most people who remove the mod and clean the barrel after each outing, just aren’t aware of the damage that can be caused if leaving this type of moddy on the barrel without cleaning. It’s just not good practice to leave any moddy or brake on the barrel when in storage without a thorough cleaning & lube first.

[Richiew]

9 hours ago, Catch-22 said:

Thanks. Yes I myself have a MAE bushless on my AI AWM.

I wasn’t implying the rear bushing itself stops back pressure, but from moddy designs I’ve used in the past, the rear end cap bushing did incorporate a series of o rings within it - thus serving both as alignment AND effectively sealing the mod over the barrel to prevent back gassing. To me it looks like the OPs mod is missing this part.

Sorry mis understood the context . Agree that there looks to be something missing here . There’s not many web pictures of the backend of these mods.

 Cheers