barrel wandering

[croc4]

I have a .223 wylde barrel that seems to wander, if I shoot rounds really slow (minutes between shots)they tend to group much better, fire them with ~30secs between shots and the groups open up. Is there a way to fix this?, some sort of stress relief process that would make a barrel more consistent?, like cryo treatment?


croc4

[kcstott]

Ok no mention of type of rifle, barrel length, twist rate, and weight, type of rest, type of sights, and magnification, Ammo type, brand, bullet weight??

distance you're shooting, weather conditions??

all this can add up

[Fjold]

Do you have a free floated barrel?

[croc4]

I didn't mention those things because I don't think they mattered, I was shooting over the course of an hour and noticed that shooting each round with 'less' time between shots caused the groups to open up under the same conditions.

but for reference
.223 wylde
18" fluted barrel
free floated tube
bench rested, 100 yrds

[meaty-btz]

1. Need more details.
2. As a barrel heats up the groups will open up. Barrels get hot, hot barrels means open groups.
3. Heat soaks into rounds, hot rounds have higher velocity than cold rounds, this will alter POI, this will open up groups.

When you wait a minute or more between shots, not only does the temp between rounds become nominal but the barrel cools much more.

Beyond that, for accurizing a firearm there is some basic components, barrel quality, rifling quality, bedding or free-floating, bull barrel vs a "light" barrel (barrel contour.. you can have a fluted barrel that isn't a heavy barrel).

Your barrel isn't wandering.. there are other elements in play.

Does barrel material make a difference in hot vs cold shooting? Hell yes.

[kcstott]

I didn't mention those things because I don't think they mattered, I was shooting over the course of an hour and noticed that shooting each round with 'less' time between shots caused the groups to open up under the same conditions.

but for reference
.223 wylde
18" fluted barrel
free floated tube
bench rested, 100 yrds

ok now how much are your groups growing?? and still no sight info??

how has the rifle shot in the past??

What changed??

[ar15barrels]

I have a .223 wylde barrel that seems to wander, if I shoot rounds really slow (minutes between shots)they tend to group much better, fire them with ~30secs between shots and the groups open up. Is there a way to fix this?, some sort of stress relief process that would make a barrel more consistent?, like cryo treatment?





croc4

Assuming it's not a sighting issue, replace the barrel.
You got a turd.
Stay away from fluting on your next barrel as it contributed to the problem.

[kcstott]

Stay away from fluting on your next barrel as it contributed to the problem.

But it looks so tacticool!!!!

No one gets that it fouls up how the barrel reacts to heat unless it is done before the barrel is heat treated and stress relieved. Never did care for flutes.

[krwada]

Fluted barrels

But it looks so tacticool!!!!

No one gets that it fouls up how the barrel reacts to heat unless it is done before the barrel is heat treated and stress relieved. Never did care for flutes.

How does one find out whether or not a fluted barrel has been properly post-heat treated and stress relieved?

Many of the manufacturers of those fluted barrels say nothing about this.

Thanks;
Ken

[ar15barrels]

How does one find out whether or not a fluted barrel has been properly post-heat treated and stress relieved?

Many of the manufacturers of those fluted barrels say nothing about this.

Thanks;
Ken

Shoot it and see how bad it wanders.
In general, the only barrels that are fluted properly are single point cut rifled barrels from the likes of krieger/bartlein as those guys do the contouring/fluting before the rifling and lapping.
Pretty much everyone else puts the fluting on last.

[krwada]

Shoot it

Shoot it and see how bad it wanders.
In general, the only barrels that are fluted properly are single point cut rifled barrels from the likes of krieger/bartlein as those guys do the contouring/fluting before the rifling and lapping.
Pretty much everyone else puts the fluting on last.

Well ... then if that is what it takes ... then I suppose just staying away from fluted barrels is probably the best way to avoid this eh?

[kcstott]

Well ... then if that is what it takes ... then I suppose just staying away from fluted barrels is probably the best way to avoid this eh?

Yep
And good shops will recommend stress relief after fluting

Fluting should not cause to much of an issue on most rifles but you won't see that stuff on BR rifles

[ar15barrels]

Well ... then if that is what it takes ... then I suppose just staying away from fluted barrels is probably the best way to avoid this eh?

That's the safest path.
There are lots of non-fluted barrels that thermally wander too though.
This can also be a function of the bore straightness.

Follow along for a minute...
A barrel blank starts as a round steel bar.
They drill a hole relatively down the middle of it.
Then, they make the grooves.
Let's assume for a second that the hole is perfectly centered and straight. (fairy tale world).
So now let's cut centers into each end with a tool like this which locates from the bore:


Now, we have a way to locate the barrel in the lathe for machining the exterior contour.
In our straight barrel, locating the barrel from the center, the barrel wall thickness will be consistent on all sides.

Now let's look at reality:
Bores are not straight.
Let's follow the same process where we locate centers on each end and machine the outside of the barrel.
Think of the bore as a jump rope shape (it's not that bad).


Now, if the outside of the barrel is machined to the center of the barrel on EACH END, but the bore is curved, the barrel will thickness will be different on different sides of the barrel.

Now let's talk about thermal expansion.
As steel heats up, it expands.
So, in our straight barrel fantasy land, the barrel wall thickness is the same on all sides and it will expand the same amount on all sides.
The net results is that the barrel stays straight no matter what temperature it is.

Jumping back to reality, there is more metal on one side of the barrel.
As the metal heats up, it expands more on the thicker side of the barrel.
This extra expansion on one side causes the barrel to bend.


The barrel is mounted to the receiver and the scope is mounted to the receiver.
This bending of the barrel as it heats up causes the front of the barrel to point to a different place than when it was cold.
This is where thermal wandering comes from.

The straighter the barrel, the less it wanders with temperature changes.
In general, the higher quality barrels are MUCH straighter than factory "production" barrels.

[ford63man]

That my friend was an excelent explanation. i am a whole lot less dumb
than i was 3 minutes ago. Thank you and please don't ever leave the
forum.

[croc4]

well, live and learn ;-/.
your explanation was awesome, makes a lot more sense now.

croc4