Effects on accuracy of moderation

[Alycidon]

I have started along the process of outing my 22.250 and replacing it with a Cooper, almost certianly in .22BR. Hard to see the hits with the 22.250 due to its recoil and it is just so noisy.

 

I also shoot a 6mmPPCUSA which has a T8 fitted, as you might guess this shoots pretty well and with the T8 I get to see most of the hits providing I keep the mag at 8x or below.

 

In a discussion with a traditional riflesmith today he stated that he believed that rifles lost an edge accuracy wise with a can fitted due to the turbulent air within the can disturbing the bullet flight. He commented that if there was an improvement or things were the same accuracy wise then the BR boys would fit them, food for thought. At 200 yards or so then he admits it will make little difference but he shoots a lot at 400 yards plus.

 

Everyone I know who has a moddy fitted has never gone back to an unmodied one, mind you I only know one target shooter I think and he hates cans. So my question is;

 

Has anyone compared a barrel that was unthreaded and unmoddied to the same barrel threaded and moddied and/or threaded with the moddy off. If so what results did you see accuracy wise?. If an improvement after the threading was the muzzel recrowned at the same time?.

 

So you BR and F class boys, what do you think?.

 

Thanks for your thoughts.

 

 

A

[Guest northernchris]

I would say the only TRUE way of testing before and after would be to machine rest the weapon,the mod will tame recoil and generally lower the POI but i would say that be of a from a combination of barrel weight and harmonics.We could test the theory as i am building a machine rest I think any gain in accuracy is from the shooters perceived/felt recoil being lower.

 

Chris

[Bambi-basher]

I think any gain in accuracy is from the shooters perceived/felt recoil being lower.

Chris

 

I disagree there Chris, the moderator will act as a large barrel weight damping the harmonic vibrations as the bullet travels down the barrel, their for leading to a more accurate rifle in theory.

 

In most disciplines of target shooting the use of moderators in not allowed, also FLO are not keen on granting them for use on a target rifle. (Put your ear defenders on when on the range).

 

The expanding gases are behind the bullet when it is in the moderator, in fact it could be argued that the baffles inside the moderator deflect the gases backwards so away from the exiting bullet.

 

Well there are my thoughts.

 

B-b

[Guest northernchris]

WHAT

 

Nope not barrel weight,ok lets strap 2 kg on the end of the barrel then see what happens!!! Take a look at the BOSS system it adjusts barrel lenght by no more than 45mm-65mm,what that does is change the frequency in which the barrel move,s.

[baldie]

I cannot recall a gun that shot worse with a can on. Few stayed the same, most had improved group sizes. A can will work the same as a brake, to a degree, letting gas in the sides, behind the bullet, ok, they cant get out the sides, like with a brake, but by the time they start to come back, the bullet will be long gone, i would think?As previously mentioned, flo,s dont like mods for range use, but that opinion is changing rapidly, my area are granting them readily, and target shooters are using them.

[varminter]

Hi guys quite agree that the only time you could prove things is in a machine rest and in a inclosed range to take all varibles out and to keep things consistent!!!

I now have a T8 mod on me 6ppc and on 12 mag i can see my hits out to 400yds , had a T8 on me 243 ackley and same thing , now have a T8 on my 6.5-284 and can spot shots out to 700yds on 12 mag and on the odd ocassion when i have been deer stalking , you can see the impact!!!

As for accuracy , its always been positive!!!

Also found when taking on multiple foxes /deer , it confuses them where the sound comes from!!!!

Just my personal experince.....

All the best guys...............

RAY........................

[Redfox]

I dont have any full bore mods, but the people I know with them all claim better groups after fitting. I too think the weight of the can helps with harmonics, the only negative would not be turbulence in the can but the exit hole acting as a muzzle being less accurate than the barrel crown.

To test the theory a machine rest and two cans of the same weight, but one with no baffles and a larger than standard exit hole would tell the real tale.

It would be interesting to see the results of such tests.

Redfox

[Bambi-basher]

WHAT

 

Nope not barrel weight,ok lets strap 2 kg on the end of the barrel then see what happens!!! Take a look at the BOSS system it adjusts barrel lenght by no more than 45mm-65mm,what that does is change the frequency in which the barrel move,s.

 

Ok Chris, take a average stalking rifle barrel with 2kg of moderator on the end of it, are you saying the peaks and troughs of the vibrations when fired will reach the same highs and lows irrespective of whether the “2kg of barrel weight” is fitted or not?

 

The Boss system changes the harmonic frequency (in theory to match the particular load you are using) but does not dampen the highs or lows of the vibrations it would have to weigh a lot more to have that effect.

 

B-b

[Guest 308Panther]

I would be interested to see if it is actually the mod that is making the improvement or if its the barrel length....

Correct me if I am wrong....But,

Many of you choose to trim the barrel length when fitting the mod....

So a comparison of the same length barrels,one with a mod and one with out might be a more accurate way of gauging the improvement(s).

If any??

And if you have opted to shorten the barrel to trim overall length...I wonder how many have unknowingly come close to the "magical" 21-3/4 inches refered to in another thread/post......

 

308Panther

[ejg223]

I built two moderators for my 223,

first one is all steel, very sturdy with a

large hole of 8mm and weighs 590 gramms.

Second one is made of steel and aluminium,

has about 50% more volume and more baffels.

Hole 6.8mm, Lightweight construction, 395 gramms.

 

Result: second one is quieter. Both group exactly the same.

Point of inpact is different.

Rifle has a 25.5" light varmint barrel 1/2x20tpi thread

 

edi

[JAYB]

I use the same moderator, T8, on three different rifles, it is always being interchanged. As far as accuracy is concerned there is definately no deterioration in fact I like to think it has improved. I know it is not very technical and I can provide no reason for it, the best I can do is to say that as far as I am concerned it works, and that will do for me.

 

John

[Vermincinerator]

Heres my 2 peneth worth,

Considering that the moderator alters the harmonics of the barrel, it can improve accuracy in rifles where handloads or factory ammo have not found the barrels "sweet spot"

If through load development the barrels sweet spot has been found, then the attachment of a moderator will alter these harmonics and change the sweet spot, effecting accuracy.

Without being disrespectful to anybody, the fact that many shooters find that moderators improve accuracy leads me to believe that the rifles are not performing to their best with whatever ammo is being used, the moderator actually tuning the barrel to the ammo.

This is exactly what Rimfire benchrest shooters do, fitting barrel tuning devices because rimfire ammo cannot be developed to suit their barrel's harmonics.

 

Ian.

[onehole]

I have had quite a few rifles over the years and in the early years never had a moderator fitted and was very happy with the way they performed and grouped.I am talking 222,223 and 6ppc calibres.Over the last 3/4 years I have been using rifles fitted with moderators and in particular the T8 and can honestly say that my shooting/grouping has been measurably better but whether that has come about by the moderator making the rifle generally more pleasant to shoot,ie less recoil/flip,noise or whatever or they have a positive effect on barrel harmonics I am not absolutely certain.Put it this way if I were pressured into a comp amongst some other anal accurate friends of mine then I would be choosing the moderated rifle to help!.

One thing I will mention is that since taking delivery of my sako75 in 222 and fitted T4 I have had real problems with accuracy!I have traced the problem to the rear bushing which on this particular rifle can never be snugged up as it has a parrallel barrel[did I spell that right?] The cause of the problem was found when I removed the bushing completely and guess what grouping was nice and tight, but on refitting all I could manage were 2 inch groups!!! Without the mod fitted accuracy was spot on so no problem with the action.I am going to experiment more with some bushing modifications but I am convinced that you either have to have a good fitting bushing and by that I mean quite tight and just snugging up with full contact on the barrel or no contact at all as partial contact only seems to have an adverse effect on barrel harmonics or something????fun in it.Just my experience may not be yours,cheers onehole.

[Ronin]

I think this has been discussed at length before on other forums.

 

However, I have both moderated and unmoderated rifles, the only perceptible difference I see is:

 

a, moderated rifle = increase in weight and balance point too far forwards.

 

b, moderated rifle = decrease in recoil.

 

c, moderated rifle I can shoot without ear muffs.

 

Now I have deer rifles and varmint rifles, those deer calibre rifles are unmoderated, for the simple reason I might walk several miles over difficult terrain and whilst I don't mind a heavy barrel, I don't like carrying anything unessential, so a moderator is out as far as I am concerned. (I would however consider having a muzzle brake fitted) Should I shoot hinds, it is still relatively easy to knock two or three over with a "naked" rifle before the herd scatters.

As does happen anyway with a modded rifle when they notice two or three sisters on the deck!

 

 

Varmint rifles, well I usually shoot my own from a stable position, that I might remain in for a few hours shooting thirty or more shots, so weight (my rifles that is) is not an issue.

 

I have done extensive load testing with my own 22-250AI which has a T8 fitted, I can categorically say that it shoots as well without the moderator as with it, the only downside is increased noise pollution should I shoot naked.

 

 

Iv'e seen theories about moderators which allow the gases produced in the firing of a cartridge to "wash" over the bullet giving it a stable cushion to launch from, personally I go with the theory that a moderator alters the barrel harmonics and therfore affords dare I say undeveloped loads to shoot better because the barrel has been stabilised to a greater degree. I think that with carefull and meticulous load development the same results can be achieved less the heavy can.

 

I have a heavy profile barrel on the 22-250AI, whith the muzzle being about .950" in diameter, so I would guess that there is little or no flex in the barrel when the "puny" .224 pill blasts down the rifling.

 

All a matter of personal preference really

 

 

 

[Alycidon]

Thanks for your comments Andy, I knew you were involved in BR and maybe F and hoped that you would have an input. Your comments on your AI with and without the T8 was exactly what I was looking for.

 

So to date then it looks like fitting a moderator is not detrimental to long range accuracy unless someone has found differently. If so please post the info here.

 

Thanks for your input to date guys.

 

A

[Alycidon]

I have had quite a few rifles over the years and in the early years never had a moderator fitted and was very happy with the way they performed and grouped.I am talking 222,223 and 6ppc calibres.Over the last 3/4 years I have been using rifles fitted with moderators and in particular the T8 and can honestly say that my shooting/grouping has been measurably better but whether that has come about by the moderator making the rifle generally more pleasant to shoot,ie less recoil/flip,noise or whatever or they have a positive effect on barrel harmonics I am not absolutely certain.Put it this way if I were pressured into a comp amongst some other anal accurate friends of mine then I would be choosing the moderated rifle to help!.

One thing I will mention is that since taking delivery of my sako75 in 222 and fitted T4 I have had real problems with accuracy!I have traced the problem to the rear bushing which on this particular rifle can never be snugged up as it has a parrallel barrel[did I spell that right?] The cause of the problem was found when I removed the bushing completely and guess what grouping was nice and tight, but on refitting all I could manage were 2 inch groups!!! Without the mod fitted accuracy was spot on so no problem with the action.I am going to experiment more with some bushing modifications but I am convinced that you either have to have a good fitting bushing and by that I mean quite tight and just snugging up with full contact on the barrel or no contact at all as partial contact only seems to have an adverse effect on barrel harmonics or something????fun in it.Just my experience may not be yours,cheers onehole.

 

 

One Hole,

 

Get a decent rifle smith to sort that bush unless you are suitably qualified/trained to do it. Just gives you peace of mind that it has been done properly and a poor shot is down to you not the moddy catching the bullet.

 

Geoff

[onehole]

One Hole,

 

Get a decent rifle smith to sort that bush unless you are suitably qualified/trained to do it. Just gives you peace of mind that it has been done properly and a poor shot is down to you not the moddy catching the bullet.

 

Geoff

Thanks for input Geoff,My smith and a chat to Jackson Rifles today confirmed there is a possibility of barrel harmonics being disturbed by a lightlly touching bushing and in the case of a parallel barrel it has to have clearance to slide on and off and its this light contact that is causing the problem.I have machined the bushings on the moderators on my RPA,s to be a snug fit and no play on tightening and they maintain zero and shoot superbly.I am going to take a few more thou off my existing bushing or do a new one on my own lathe to get complete clearance on the bushing and as long as my Sako will return to zero each time I fit and refit the moderator I,ll leave it at that .At the range today I borrowed a friends mod that he had on a similar sako that had much more clearance and tried it on my rifle just to see what happened,the result was back to a tight group again.I would prefer a decent purchase to the barrel on the rear bushing as this ensures zero to be held and only hope the screwcutting and facing will be able to support long term fitting and refitting on its own.If there is anyone out there with some thoughts on this it would be interesting,thanks onehole.

[Alycidon]

Onehole,

 

You sound like you know exactly what you are doing and you are heading in the right direction.

 

My T8 was fitted by Callum, the rear bush is in firm contact with the barrell.

 

A

[eldon]

One Hole,

 

Get a decent rifle smith to sort that bush unless you are suitably qualified/trained to do it. Just gives you peace of mind that it has been done properly and a poor shot is down to you not the moddy catching the bullet.

 

I fitted a T8 onto my 700 VS .308 and experienced similar problems. I think the design suggests 1 thou clearance but the problem is measuring this especially with a tapering barrel.

After a few trys I made a holder for the bush as you cannot hold and measure accurately without. I read somewhere that it is beneficial to squeeze the mod i.e. hold in compression, by having the bush tight.

I always remove mine after a day out ( rust) and get consistent results on refitting.

Paul

[onehole]

Will let you know how I get on with a free floating bush set up.I know the rifle is accurate ,its just that i am anal about maintaining a perfect zero.Need time and weather now to do an honest assessment.cheers onehole.

[Guest northernchris]

One hole

 

I run my Sauer with 3 thou clearance on the rear bush of the A-Tec,but the Wildcat lightweight like's to have interferance fit on the Styer.Like Ian said about finding the 'sweet spot' i think each rifle is different.I know Norman Clarke run the mods (T8) with the bush pretty tight.

 

Chris

[Guest northernchris]

Double Post

[Vermincinerator]

Hey Andy,

I like the idea of shooting "naked"

 

Ian.

[cooperman223]

I will let you know when i get my cooper back, it shot well without a mod, but i decided to have a one fitted, its been away for about two months now. The actual threading took half a day to do, but its been away for proofing for quite a bit of that time, i have been assured it is on its way back very soon.

[6mmBR]

I know what it's like the proof house is running slow at the moment. My .22-250 Ackley has been there for a fortnight

Cheers

Dave