Barrel material - Chrome Moly or Stainless - preferences please

[baldie]

Thats absolutely ridiculous.

The absolute critical part of a muzzle thread , is a 90 degree square bottomed shoulder. This is what a moderator locks up to, NOT the thread .

I can see why they haven't done it,purposely for their brake, and a brake only two inch long, and bored for a .338 isn't going to have problems, when simply clamped onto the thread.

A 7" long moderator, is an entirely different kettle of fish though.

A gun with a thread like that Varm, is not fit for purpose, as it should SAFELY accept ANY device. I would send it back, and tell them to sort it out.

 

[ejg223]

the two CTR's I have don't have the thread cut right back. No Problem if one counter bores the moderator to suit. My Hauskens fitted as they came. Some will say this is not the way it should be done however I see it as being a sturdier/stiffer solution than cutting the recess at the shoulder. My CTR's both shoot extremely well.

The only Issue I have is with the Hausken mods that they have a very small bore for cal. All three of my Hausken mods are bored out to a more normal diameter for cal and I got rid of fliers.

edi

[bradders]

Most factory finished muzzle threads...and plenty of after sales threaded muzzles I've seen look just like that, and plenty of aftermarket muzzle attachments are counterbored to accommodate such like

It's easier, and a little neater for the aftermarket threader to cut a recess at the end of the thread with a parting or grooving tool as stopping the threading operation in the same place each time can be a challenge, and grooving it will clean up any straggly bits.

I wouldn't say you are weakening anything, as you're only going as deep as necessary, ie the thread depth

[Decessange]

"As such I'd be very interested to hear what barrel material forum members are using, your reasons for doing so and your experiences with each."

I have a Tikka T3 Varmint in 6.5x55 SE with factory chrome moly barrel. Best group I ever shot with this rifle was an 8 mm (measured center to center) 5 shot group at 100 meters.

With an Oberland OA-15 M1 .223 semi auto (Lothar Walther stainless bull barrel) I managed an incredible 4 mm 5 shot group again @ 100 m.

The next rifle is a Winchester Model 70 Heavy Varmint in .223 with factory stainless barrel from the mid nineties which I bought recently second hand. Best result up to now: 10 mm 5 shot group @ 100 m.

And finally a CZ 527 Varmint in .223 with factory chrome moly barrel which I have not yet got under a 13 mm 5 shot group @ 100 m. I am confident however that some trigger and eventually bedding work may help to improve this.

I didn't buy any of these rifles on barrel material alone. In former years I favoured chrome moly over stainless. Nowadays I feel that a stainless barrel is easier to clean and may have a slight edge in accuracy.

For those who might be interested: The Oberland has a 1:8 twist, the Winch and the CZ are 1:9.

Regards Ladies and Gentlemen and my best wishes for the New Year.

J.C.D.

 

 

 

[VarmLR]

15 hours ago, baldie said:

Thats absolutely ridiculous.

The absolute critical part of a muzzle thread , is a 90 degree square bottomed shoulder. This is what a moderator locks up to, NOT the thread .

I can see why they haven't done it,purposely for their brake, and a brake only two inch long, and bored for a .338 isn't going to have problems, when simply clamped onto the thread.

A 7" long moderator, is an entirely different kettle of fish though.

A gun with a thread like that Varm, is not fit for purpose, as it should SAFELY accept ANY device. I would send it back, and tell them to sort it out.

 

I hear the arguments others are making about counter boring a mod to suit but when paying out so much for a rifle in the first place, there should be no need to lift a finger to counter bore anything.  It should fit first time and be fit for purpose.  My argument to GMK was that it is not fit for purpose and is flawed and potentially dangerous to leave things like this dependant of course on the fit of the mod in the first place.  

After two months or so of going back and forth between the retailer, GMK and Tikka, the solution is far from ideal or acceptable, but as the dealer has tried to sort things out by offering an alternative mod (not the one I would have chosen or want)  FOC that should work fine (ie a 30 cal mod fitted to a 6.5 which wont be as efficient) all I can do is try it and if it doesn't work out I'll be demanding a refund or that a competent smith sorts out my thread.  I was particularly annoyed at the insistence from others in this chain that you shouldn't use a 260 mod on a 6.5 if shooting long bullets because they will yaw and strike the inside of the mod.  This claim was challenged but the person making it rebuffed the challenge by saying that Peter Jackson insists this is the case and that 6.5 users should use 30 cal mods for this reason if shooting long bullets. That's a new one on me!!!  Stable is stable.  There should not be instability at the exit to cause a bullet to strike the inside of the mod.  I have shot long for cal bullets from other cals using cal specific mods with no issues whatsoever so I find the whole argument deeply flawed to say the least.

Tikka's response has really put me off ever buying another of their rifles.  They couldn't care less as their view is that most buyers will be in the USA and as such the design was for a muzzle brake which works fine with it.  GMK and the dealer have come up with a solution of providing a machined bushing to be supplied with all newly supplied Tacs which in their view dispenses with the problem without resorting to counter boring each and every mod to suit.

I must admit that I feel let down by all concerned as it just smacks of spoiling a good hull for the sake of a pennyworth of tar!

[baldie]

Just looking at Edi's picture, several things occur to me.

The step at the rear is an American way of cutting a thread. They say its there to "align" a brake or mod. That means the device needs a counterbore. That also means that the said device is actually aligning itself on that step. If its to be of any use, it needs to be a very close fit indeed on that step. That could throw it off axis, unless the thread fit is loose. It will also affect the fit twixt barrel shoulder and rear of said device, if the threads are not 100 %.

The giveaway on that picture is the chamfer on the end of the barrel shoulder.

Anyone who has ever cut a thread correctly, clocked off the bore, will know that the outside diameter of the barrel, very rarely runs exactly concentric to the bore.

Hence, if the bore was clocked and the barrel then threaded, the chamfer on the outside, would show as uneven.

If the barrel was held in a 3 or 6 jaw, and its thread cut, not only would the thread be off, to the bore, but the chamfer would show as even.

You can't have your cake, and eat it.

The only way to have concentric threads to the bore, and also a concentric chamfer, is to cut the threads, crown, and then re indicate the OUTSIDE of the blank to chamfer.

Would that be done on a factory barrelled rifle ?   Hmmmmn.

However, your barrel is a simple fix.

It just needs to go in the lathe, have its bore clocked and a proper undercut , cut in place at the back of the thread, and the thread checked for concentricity at the same time.

Personally, I would lop it off, and do it all afresh, for peace of mind.

You shouldn't have to do that on a new gun though, for me.

[VarmLR]

I agree baldie.  At least the dealer has bent over backwards to try and help though.  They've been caught out as much as I have by this.  For them, with so many flying off the shelf, they'd lose out of they had to send every rifle to have the bore clocked and an undercut made then tested.  I can see why they're offering compression bushes (as they phrased it) instead.  I went in today and walked out with a brand spanking new mod to replace the one that was chewed up and just in case there is an issue, I accepted the 30 cal mod.  Instead of the one GMK offered (which I didn't want) I got the Aimsport one I was after.  I noted that some other manufacturers' mods for 6.5 were in fact labelled as ".243 up to 30 cal" instead of specifically bored for 260/6.5.  I still have the option of having the thread undercut but that would be at my own cost if I wanted it done as GMK are only willing to provide the solution they have on their terms.  It wont be much to do but the whole afair has left a bitter taste in the mouth.  Why the heck couldn't Tikka do it properly in the first place...I had my other T3 threaded after I bought it and have never had an issue with that one (squared up to the barrel shoulder).

[baldie]

A crush washer never occurred to me.

That will solve your problem, because basically it is removing the step by covering it, allowing the rear of the mod to align with the barrel shoulder.

Don't think you will have any more trouble with it.

[bradders]

You're not going to crush a crush washer with a hand tightened moderator.

A peel washer would be different though

Out of curiosity what diameter are your threads?

[VarmLR]

Threads are 15 x 24 from memory bradders.

[ejg223]

If every mod were designed with a small counter bore and every barrel with a recess one might have a chance that at least one is done properly and chances are high the mod will fit. I have had several mods not fitting on several different rifles also on cheapy thread jobs where I needed to counter bore the mod. Worse is when a barrel is made to fit some possibly out of spec mod thread... that is then the only mod that will fit on that barrel.....

Anyway my two CTR rifles with 5/8x24 non recess threads shoot absolutely fantastic. I will leave them that way.

edi

[eldon]

1 hour ago, VarmLR said:

Threads are 15 x 24 from memory bradders.

I think you might have imperial and metric numbers combined there.

How about 5/8ths (or 9/16ths) x 24 pitch (i.e. UNEF)

or 15mm x 1.0mm pitch (most likely option). 

[VarmLR]

You're absolutely right....it's 5/8ths x 24....don't know where the 15 came from!

[bradders]

I had 5/8" stainless peel washers made a while back and still have some left.

Depending on the width of that shoulder behind the threads then might work

Mine are .040" thick (1mm), let me know if that would help

[brown dog]

On 22/12/2017 at 5:30 PM, meles meles said:

Indeed so. 

 

For most people a chrome moly barrel is quite good enough, and stainless barrels, irrespective of which particular flavour, aren't inherently more accurate. They are just a little more forgiving of poor care, hot loads and high rates of fire. In ascending order, we'd recommend:

• Chrome Moly
• Austenitic stainless steel (316L or even 317)
• Martensitic stainless steel (416)
• 600 series precipitation hardened (630, PH17-4, LW50)

Harken to what Baldie says though: how you use and care for it will have a greater effect on barrel life for most shooters.

Only just caught up with this thread. Fascinating stuff and awesomely expert.

My thick take on the original question is 'always stainless' - based on simple reasoning that I wouldn't buy a non-stainless knife for practical outdoor use, cos, without pampering, it'd rust.

[bradders]

12 minutes ago, brown dog said:

Only just caught up with this thread. Fascinating stuff and awesomely expert.

My thick take on the original question is 'always stainless' - based on simple reasoning that I wouldn't buy a non-stainless knife for practical outdoor use, cos, without pampering, it'd rust.

The best blade steels aren't stainless though, but it's all preference

They shoot as well as each other, but one might take a bit more care, and a good gun maintaining regime is to apparently clean and oil the barrel after each outing.

Military spec service rifle barrels are generally CM steel, albeit with a chromed lining for anti-corrosion purposes, if it was that critical they'd spec Stainless.....but they don't

[brown dog]

1 hour ago, bradders said:

Military spec service rifle barrels are generally CM steel, albeit with a chromed lining for anti-corrosion purposes, if it was that critical they'd spec Stainless.....but they don't

They're also generally hammer forged, for cheapness, which I suspect is the primary driver for that choice, and I would suspect that there are multiple other economies of scale for mass production (ie non-stainless is cheaper) and production (tooling wear etc?) that drive military-lowest-bidder choice away from stainless.

[brown dog]

1 hour ago, bradders said:

The best blade steels aren't stainless though, but it's all preference

Think that'd have to be answered with 'define best'.

If it's only in terms of sharpness, then yes. But if it's 'best for intended application', then no.

Best for making razor sharp edges? Yes

Best for dive knives etc? No

[meles meles]

Agreed: we should consider 'fitness for purpose' rather than 'best'.

Some of the best blade steels are actually stainless, for example 12C27 can take an awesome edge and gives the benefits of corrosion resistance, long life and a fair degree of toughness but it can be difficult to get it sharp in the first place and it's not the easiest steel to work with. As a good all round steel, the carbon tool steel O1 takes some beating for cutting edges, but needs some care to prevent it rusting. End use and operator skill are what really matters...

[Laurie]

47 minutes ago, brown dog said:

They're also generally hammer forged, for cheapness, which I suspect is the primary driver for that choice, and I would suspect that there are multiple other economies of scale for mass production (ie non-stainless is cheaper) and production (tooling wear etc?) that drive military-lowest-bidder choice away from stainless.

I'm 100% sure that is the case. Also, it's interesting how it is military pressure that is driving advances in propellant R&D and manufacture towards so-called 'copper eraser'  types, presumably to allow rough, nearly shot out barrels to keep going under adverse conditions. Or ... maybe to cope better with barrels that are internally 'rough' from new?

[baldie]

I would think the military use hammer forged barrels for the fact, they last many times longer than cut or button rifled stainless.

Hammer forged barrels usually "let go" when wearing out. I've borescoped several sako's/Tikka's where one of the lands has simply disappeared for a couple of inches. They don't seem to degrade evenly like a button/cut barrel when shot out. I would say the steel is more "brittle" when at the end of its life, and lumps simply come off.

Re barrelled a couple of TRG's recently that were like that. One, a .338 had only fired 1500 rounds.

The rest of the lands were fine, but one was missing for a few inches at the breech. 

[Moorlander]

1 hour ago, baldie said:

I would think the military use hammer forged barrels for the fact, they last many times longer than cut or button rifled stainless.

Hammer forged barrels usually "let go" when wearing out. I've borescoped several sako's/Tikka's where one of the lands has simply disappeared for a couple of inches. They don't seem to degrade evenly like a button/cut barrel when shot out. I would say the steel is more "brittle" when at the end of its life, and lumps simply come off.

Re barrelled a couple of TRG's recently that were like that. One, a .338 had only fired 1500 rounds.

The rest of the lands were fine, but one was missing for a few inches at the breech. 

The Finnish Army found out during a test/trails program and 7 years of actual service that the barrels of their Sako TRG-42's lasted 3000 to 4000 rounds with Lapua Lock Base B408 factory ammunition before showing impermissible accuracy decay. The Finnish Army consistent accuracy requirement for these rifles is ? 1 MOA at 1000 m. If this requirement is not met the TRG-42 gets a new .338 Lapua Magnum barrel. This is normal practice for active high performance precision rifle operators who regard barrels as expendable items. The continuous use of very powerful handloads (which results in higher muzzle velocities) resulted in much quicker throat erosion reducing the TRG-42 barrels accuracy life to 1000 to 2000 rounds.

 

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