Cold bore zero versus (very) Hot bore zero “test”

[Team4LongGun]

This one has gone way off the original topic. Let's get back. No more sidebar discussions or jokes are needed.

 

[Marbles]

This one has gone way off the original topic. Let's get back. No more sidebar discussions or jokes are needed.

Wilco.

 

[White Wizard]

I had a Kimber mountain ascent in 6.5cm. I GUARANTEE there was a shift on the third shot if they were inside a few minutes. No question.

 

[BjornF16]

I had a Kimber mountain ascent in 6.5cm. I GUARANTEE there was a shift on the third shot if they were inside a few minutes. No question.

No one is saying it doesn't happen; but rather IF the barrel is properly stress relieved AND there are no pressure points on barrel AND the action is stable within the stock, THEN there shouldn't be any shift.

I had a Kimber MA. It needed work to relieve pressure within the action/stock interface. That improved it significantly for 3 round groups.

 

[Billy Goat]

I had a Kimber mountain ascent in 6.5cm. I GUARANTEE there was a shift on the third shot if they were inside a few minutes. No question.

This is demonstrating what should be happening, not saying it doesn't, but that it doesn't have to.


It's like how I use to expect to re-sight a firearm 10 years ago, riding around in a truck or tractor would knock the scope off. I switched to a lot or trijicon around 8-9 years ago, a lot of those problems went away. Now it's been demonstrated why.


So the discussion becomes why put up with issues like scopes not holding, rings not holding, actions moving, or barrels that get contact or simply move with heat. Life is too short, ammo too precious. Burn ammo up learning your rifle, not chasing a zero.

 

[MoH08]

Besides the trolling, this has been extremely informative for a FNG trying to step up his game regarding his rifle setup. Thank you for conducting such a test! What does stress relieved mean and how do you confirm if your barrel is or is not?

 

[Marbles]

Besides the trolling, this has been extremely informative for a FNG trying to step up his game regarding his rifle setup. Thank you for conducting such a test! What does stress relieved mean and how do you confirm if your barrel is or is not?

Stress relieved refers to heat treatment at specific temperatures to relieve internal stress in the metal that results from working it.

If you take a paper clip and bend it, the first bend does not cause much issue, but keep doing it and we all know the results. This happens because of work hardening and accumulation of internal stress in the material.

The only way to know is if the manufacturer tells you. The end goal of that step in manufacturing is to have a quality barrel, so testing it as discussed here also works, if a barrel shoots well, who cares how it was made (though it was likely made well).

 

[2y2c]

Is there some sort of consensus on whether or not fluting of any kind will affect the stress of a barrel ?
And is properly stress relieving more important in skinnier barrels than heavier ones?

 

[Marbles]

Is there some sort of consensus on whether or not fluting of any kind will affect the stress of a barrel ?
And is properly stress relieving more important in skinnier barrels than heavier ones?

It would depend on how the fluting is done, heat from a dull cutter could certainly introduce stress and work hardening. In general, when done well, my understanding is fluting is not an issue.

 

[2y2c]

I’ve seen on a couple guns that the velocity of the first shot will be consistently lower than all the rest of the shots. I’m guessing it has to do with the expansion of the steel as the temperature changes. If the first shot is always slower, I think it would matter at distance.

We were using labradar on one occasion and a magnetospeed on another. The guy with the labradar says that gun is always about 30fps slow on the first. The 100 yard groups are fantastic, but I’d think 30fps wouldn’t show up at 100.

Has anybody else seen this happen with other guns or is it just an anomaly of a couple barrels?

 

[Marbles]

I’ve seen on a couple guns that the velocity of the first shot will be consistently lower than all the rest of the shots. I’m guessing it has to do with the expansion of the steel as the temperature changes. If the first shot is always slower, I think it would matter at distance.

We were using labradar on one occasion and a magnetospeed on another. The guy with the labradar says that gun is always about 30fps slow on the first. The 100 yard groups are fantastic, but I’d think 30fps wouldn’t show up at 100.

Has anybody else seen this happen with other guns or is it just an anomaly of a couple barrels?

If the gun has been scrubbed, I can see that as carbon likely changes the interaction between bullet and barrel.

If the gun is shot, then left to sit for a bit, is it still slower on the cold shot?

 

[2y2c]

I haven’t cleaned mine in a few hundred rounds. Neither gun had a clean bore.

And I’m talking cold bore like it hasn’t been shot in a day, not shot ten minutes before and left to cool.

 

[Billy Goat]

I’ve seen on a couple guns that the velocity of the first shot will be consistently lower than all the rest of the shots. I’m guessing it has to do with the expansion of the steel as the temperature changes. If the first shot is always slower, I think it would matter at distance.

We were using labradar on one occasion and a magnetospeed on another. The guy with the labradar says that gun is always about 30fps slow on the first. The 100 yard groups are fantastic, but I’d think 30fps wouldn’t show up at 100.

Has anybody else seen this happen with other guns or is it just an anomaly of a couple barrels?

I'd think it's most likely a factor of chamber heat. Warming powder, when it's not a temp stable powder. It's not hard to test.

A lot of time ES and SD doesn't play out at distance like you think it would.

 

[Castle Rock]

Years ago I bought a really nice model 7 in 260
That damn thing would string shots about 5 inches over 5 shots but I loved the rifle and decided I was either going to fix it or **** it with my home solution stress relief method

I put about 50 rounds through it as fast as I could, the barrel channel even started to smolder and I had to douse it with water

But damned if that didn’t turn that rifle into a solid 2 MOA gun

 

[chamois]

My experience has been that I have not observed a difference in impact point from a cold bore shot and a hot barrel greater than the shot to shot variability within the "cone" of each particular barrel.

I have observed a difference when the first shot was from a cold AND clean-to-the-steel barrel. It did not happen with all my rifles, though. Some did, and most didn`t.

That was in the old days when I was a little obsessed with barrel cleaning, which I am not anymore.

 

[wind gypsy]

Years ago I bought a really nice model 7 in 260
That damn thing would string shots about 5 inches over 5 shots but I loved the rifle and decided I was either going to fix it or **** it with my home solution stress relief method

I put about 50 rounds through it as fast as I could, the barrel channel even started to smolder and I had to douse it with water

But damned if that didn’t turn that rifle into a solid 2 MOA gun

I love it. Has to be the coolest method of stress relieving i've heard of.

 

[slatebuilder]

@Formidilosus the information you post here is excellent to read and digest. Thank you for taking the time to do this stuff.

I have been shooting high power silhouette matches since the early 90’s. If you’re not familiar, the matches are 40 off hand shots at steel silhouettes ranging 2,3,4, and 500 meters. Including warm up/sight in a match day accounts for about 60 shots fired over roughly 3 hours, sometimes more or less depending on the number of competitors. While barrels get warm, they do not get scorching hot. Think unpleasant to touch, but not actually burn you. Your points in this thread about barrel heat and cold bore verses hot bore are understood and well taken.

My questions are this.
How does one determine whether barrels are properly heat treated and manufactured when purchasing new rifles? Examples would be typical hunting rifles that a guy might look at, Ruger Americans, Weatherby Vanguards, Henrys, Remington 700, Tikka t3’s, etc come to mind.

What about older rifles? How does one determine whether barrels were built correctly and what wasn’t on older stuff?

 

[Formidilosus]

My questions are this.
How does one determine whether barrels are properly heat treated and manufactured when purchasing new rifles? Examples would be typical hunting rifles that a guy might look at, Ruger Americans, Weatherby Vanguards, Henrys, Remington 700, Tikka t3’s, etc come to mind.

Some are, some aren’t. Tikka, Sako, and the other European and Scandinavian brands are across the board. Rugar, Weatherby/Howa’s, Henry’s, older Remingtons, etc- sometimes. They aren’t consistent.

For those, shoot them, get them hot and see what happens.

What about older rifles? How does one determine whether barrels were built correctly and what wasn’t on older stuff?

Depends on how old you mean by “older”. But, same as above- shoot them and get them hot. Most factory rifles made before 20-30 years ago, especially American made ones, are suspect at best.

 

[TaperPin]

Not long ago I heard a guy saying he had a new Shilen barrel installed and his groups would walk 1-1/2 moa over 10 shots, which is huge. His gunsmith removed the barrel and sent it back to Shilen and they found an “anomaly” in the steel near the chamber and replaced the barrel. Apparently even custom barrels have hiccups once in a while. The replacement barrel shoots great and doesn’t walk at all.

 

[PBBananaHammock]

@Formidilosus two questions:

1) With modern quality barrels, what then would warrant a thicker barrel contour short of a reduction in POI for mounting heavy things on the barrel, machine gun use, or added weight for recoil reduction?

It seems with modern barrels, most of the reasoning is tied up in anecdotes and myth, or misinterpreting results. Ie. An assumption that thick barrel contours are more accurate due to heat and etc, when in reality the shooter is likely just more accurate due to the increase in rifle weight.

2) When using a suppressor, have you noticed any detriment in accuracy/barrel life due to heat with threaded barrels that have a smaller thread diameter paired with a larger bore? Thus having less “meat” at the muzzle and being more susceptible to heat.

For example, I’ve heard threading something like 6.5 or 308 with a 1/2x28 reduces the mass at the muzzle to such an extent that the muzzle can swell and deform under heat (especially with the added heat of the suppressor being mounted over the muzzle trapping heat further). There is physically enough metal there to do the thread job but allegedly not enough to withstand the heat stress.

For this very reason (and for want of a bigger shoulder), I had a 6.5 threaded at 9/16x24 for the extra mass, then affixed a permanent 9/16x24 to 5/8x24 adapter for the convenience. Not sure if this is just a theoretical problem that creates extra steps or a realistic one.

Hope that was understandable. Would appreciate the insight.