quote:

The heating barrel will expand in wall thickness and it will grow longer too.

RIP,

The hole in the barrel will definitely get bigger in diameter. Ring gears use to be put on the fly wheel by heating the ring gear. My father was a motor mechanic and I saw him do that plenty of times when I was a kid.

Mike

Mike,
Well, O.K., I'm wrong, but your Pop had to heat them pretty hot to get expansion didn't he?

If there was significant heat expansion then any barrel would go south pretty quickly. The barrel would have to be expanded right out to the muzzle, and when would this ever be a factor except in a machinegun.

So does a machinegun start spraying its tracers in sustained fire? That would be easy to observe, eh?

Anyway this is not an issue of importance here to be used in forgiving a too-sub-caliber bullet.

Barnes needs to make bigger diameter bullets.

quote:

Originally posted by RIP:


Barnes needs to make bigger diameter bullets.

Can't be done with their "banded solids" because the "bands" are way too wide and overstress barrels as it is. Hence the under-diameter bullets as a feeble attempt to remedy a design flaw.

quote:

Well, O.K., I'm wrong, but your Pop had to heat them pretty hot to get expansion didn't he?

Very Hot

However, I agree with you that I doubt very much that barrel expansion would have any impact of bullet stability.

I only posted about the ring gear because many people think the inner diameter of a tube will either stay the same or get smaller when it is heated.

Mike

quote:

Originally posted by 500grains:

quote:

Originally posted by RIP:


Barnes needs to make bigger diameter bullets.

Can't be done with their "banded solids" because the "bands" are way too wide and overstress barrels as it is. Hence the under-diameter bullets as a feeble attempt to remedy a design flaw.

Very true. Especially with the brass solids being harder than copper. I have measured some of the old Barnes X-Bullets (copper of course) in .404 Jeffery and they are true 0.423" diameter solid shank bullets.

I still have 76 of these old .423/350gr X bullets, that I got from Yoda Ray, before he moved on to The Higher Plane. May The Farce be with him.

Enough evidence is in for me to be convinced. Stay away from the Barnes bullets and focus on the many other good quality bullets out there.

DISAGREE ,.,., X bullets ,while perhaps are not better than some of the cool bullets .........Are redilly available , come in many of the sizes I use and kill animals like a house afire........They also tend to not blood shock meat as bad as many other bullets.....

I dont know the physics of it, but Mike is right. If I have a gear to get off a shaft or the inside of a blown bearing I always put a torch to it to expand things and will come right off then. Not sure why it expands outward but not equally inward??

I typed that last note when the computer was off and hadnt read any posts since Mikes. But, it doesnt take a color change to the metal to expand things enough to slip off a shaft.
As far as a machinegun spraying in sustained fire .... yes, it will scatter them like hell when it gets hot, we always called it a " cone of fire" as thats the shape the fire pattern makes when she;s heated up.

TSJ,
Must be that the expansion inward is blocked by compression forces and it will expand outwardly due to the path of least resistance?

I have heard of the "cone of fire," but that can be due to the vibration of the the entire gun and the mount in full auto, in addition to any barrel vibration/oscillation. If the barrel expanded enough to keyhole the bullets, then the "cone of fire" would be more like a "sparkler."

Gumboot458,
I loved the old Barnes X bullets, and the new TSX's if they don't keyhole in the particular rifle.

I would not want to have to use the Barnes brass "banded" ogived-flat-nose solid in any rifle if I could possibly get some GSC FN's or North Fork FP's.

Seems to me that Mike at North Fork tried the .474" diameter on his FP and CP banded bullets and had to go to .475" due to less problems (some keyholing with .474" was showing up in some rifles).

The expansion ratio for carbon steel is .00000633 per degree F. I shrink fit parts on a regular basis, and I can assure you that the bore of a cylinder increases as it is heated.

I think bore diameter is tangent to the problem.

Number 1: A feeding problem, it don't feed, you can't fix it, I want my money back.

Number 2: Keyholing Barnes solids. Well we all know some rifle don't work with some bullets. The smith says the rifle shoots other bullets. I say prove it. If you want to shoot a monometal bullet, have him try Northforks and GS bullets.

Dave

This place is great! A learning experience.

nopride2,
Is that a coefficient of volume expansion, or linear expansion?

I gotta go back to my old college physics book and the CRC tables ...

Lessee: "If there is a hole in a solid body, the volume of the hole increases when the body expands, just as if the hole were a solid of the same material as the body."


So how much will a change of 100 degrees F in a barrel increase the groove diameter?

Assuming that is a coefficient of linear thermal expansion:

(100 x .00000633 x .4230") + .4230 = .4232678" ~= .4233"

Maybe this is significant if the bullet measures only .4217" in diameter.

Maybe this is significant if the bullet measures .4220".

That is more than a .0012" discrepancy between groove and bullet.

Ron,

The 404 J is a heap of shit and everyone should have a 378.

I thought I should bring this thread back to Big Bores so as to prevent a delete or a move to Misc forums

Mike

Mike,
Good idea. So kind of you to walk me through this.

quote:

The 404 J is a heap of shit and everyone should have a 378.

Spoken like someone that has overdosed on kangarooshit lollypops

Vapodog,

Read the second line of my posting.

Mike

quote:

Originally posted by RIP:
"If there is a hole in a solid body, the volume of the hole increases when the body expands, just as if the hole were a solid of the same material as the body."

Oops. That's what I should have said!

But applying a coeff. of linear expansion to a hole? Hmmm. Doubt that that applies.

RIP,

What about this.

Takes two strips of metal both 12" long.

Heat one strip of metal and then make a circle with that strip. Make a circle with the strip that was not heated.....which circle will have the biggest inner diameter.

Mike

quote:

Originally posted by vapodog:

quote:

The 404 J is a heap of shit and everyone should have a 378.

Spoken like someone that has overdosed on kangarooshit lollypops

Not just any Kangaroo mind ya.....but a BIG BORE Kangaroo.......the best lollipops come from big bores!

RIP , way back when, we tested some stelite lined barrels in the M249 SAW (5.56 round).
It was mounted to a pintal to check the accuracy at sustained rate of fire ( around 85 rounds per min) Accuracy was good at that rate but when used at normal setting, 725 RPM or max setting 1,000 rpm accuracy sure went to hell in a hurry. Some would surly be due to vibration, harmonics ect. But to spray like it did compared to sustained rate heat must have played a part.

TSJ,
Thanks.
Taking it up a notch to 400 degrees F barrel temperature increase with .224" groove diameter:

(400 x .00000633 x .2240") + .2240" = .2245672" ~= .2246"

And so one ...

Talked to Harlan with Triple River. He did not slug the barrel but said that he talked to the person at McGowen who said that the barrels measure .4241. He said McGowan is looking into the issue and they may need to replace some of the barrels.

quote:

Originally posted by MJines:
Talked to Harlan with Triple River. He did not slug the barrel but said that he talked to the person at McGowen who said that the barrels measure .4241. He said McGowan is looking into the issue and they may need to replace some of the barrels.

Holy Cow!

Thanks for the update.

quote:

He did not slug the barrel but said that he talked to the person at McGowen who said that the barrels measure .4241.

That may be the story but you still have to measure the barrel to know what it really is.
Not even the benchrest barrel makers hold to a specific dim ±.0001

Mike

.4241"

If that measurement is accurate, you're screwed for even standard sized landed solid bullets.

Don't you just love it when a barrel/bullet-maker gets "creative" on diameter?
I feel for ya' MJ! Now I know why I don't have one...

Rich
NRA LifeMember
DRSS

RIP,

Have you slugged your barrel? Mine is a McGowen barrel, 1-in-10 twist and Triple River says that McGowan maintains that the rifling button (?) used to make mine is what they use on all of their barrels.

Mike

MJines,
I have not slugged the barrel on my CZ but my gunsmith slugged the barrel of my stainless McGowen .404 Jeffery on the M70, and he said it was .423", but now I am wondering a bit about the precision of his measurements. My high velocity, low pressure .404 Jeffery African Sheep Rifle could be sloppy too? Well it sure works well with the bullets I have for it, and I certainly would not change that barrel!

My .423 Lapua uses a McGowen Stainless barrel and it is very accurate with North Fork and GSC bullets. Haven't had that one slugged either.

I'll have to get my CZ slugged, as all I have tried in it are Woodleighs that did not give any keyholing.

I may have to have a barrel replaced too, if you do, it seems. That is a bummer.

Ah, well, I'll be waiting for a .395 barrel that slugs .395 hopefully, and the rifling button for that is a special order.

Until further notice it would seem that .404 Jeffery CZ rifles and McGowen barrels in this caliber should be avoided. Shite happens.

Good to have MJines on the case, getting to the bottom of this, sorting it out.

Lothar Walther barrel sales in .404 Jeffery with 14" twist were never in jeopardy anyway.

At my machine shop we make an internal splined gear that is mated to a splined shaft.

Because of tolerances, we heat the gear in the oven and we pack the splined shaft in dry ice.

They have to be aligned and pinned. We only get one chance!

From our point of view, when heated, bores expand.

RIP

First, you have to differentiate between softs and monolithic landed solids. The two have nothing to do with each other, when talking about precision fit between bullet and barrel . Virtually all soft points will "bump up", at least a little. For instance, when I shoot my 411 softs in my 405 Win that has a .4131" groove diameter, there is no problem at all. The recovered bullets measure .4131". I would not expect any issues with 423 softs in a 424 barrel. To the best I can measure, mono solids don't bump up at all. The fit you start with is as good as it will get.

Whether there is a problem with the bullet coming up to rotation or not, basically boils down to two issues, material and volume displacement.

A harder material such as the brasses and bronzes are stronger and it takes less total volume displacement for them to get a good purchase on the rifling. All else equal, a softer material would require more volume displacement for a proper purchase. The Barnes is of a harder material and there is rarely a problem gripping the rifling, even with their usual ~.001" undersize condition IF the barrel is of the nominal size one would expect the bullet to be fired down. The bullet at .001" under and the barrel .001" over is a little too much to ask.

If anyone cares, I consider a barrel with a groove diameter of + or - .0003" and a rifling height of .003 to .005" to be "on spec". Outside that range and you might have to be satisfied with conventional solid bullets. They have worked for a long time and still do.

The second issue is volume displacement. Volume displacement is a symbiotic relationship between the bullet design and the barrel design. Assuming that the bullet design is fixed, then what characteristics of the barrel determine whether the bullet will or will not work? This one is more complicated than just groove diameter although groove diameter is usually the smoking gun.

It boils down to whether the rifling design displaces sufficient material (cubic inches, cubic centimeters, cubic cubits, or whatever way you wish to measure it) to provide the needed grip on the bullet. In addition to the issue of the match of the bullet's OD and barrel's groove diameter, rifling comes with wide lands or narrow lands, tall lands (small bore diameter) or short lands (large bore diameter), and to some extent, even rounded or worn lands. Any combination of the above conditions that bring the total volume displacement below the level which is needed for (the material and design of the bullet) the bullet to be properly gripped, will, at best, be inaccurate and, at the worst, cause the bullet to tumble, meaning the engagement was so poor that the bullet never came up to rotational velocity.

If the bullet is smooth sided, it is rare that there is insufficient volume displacement, no matter what the rifling looks like. The smooth side provides plenty of material to be displaced, even on an undersized bullet such as a Barnes X (pre TSX), or a Woodleigh steel jacketed solid (usually ~.0005+" undersize).

FYI, I have never seen a problem with bullet rotation IF the bullet OD and the groove diameter are a good match. The strength or weakness (shallow or narrow) of the rifling only comes into consideration when the fit of bullet and barrel is marginal. I made a special run of solids for a gun with an off-spec groove diameter (small) and matched the bullet to the barrel. The slug indicated the shallowest rifling that I have ever seen, probably not much more than .002". Still, there was no accuracy or stability problem because of the proper bullet/barrel fit. But with rifling that weak, even a .0005" mismatch would have been disasterous.

I am not surprised that the BArnes worked fine at lower velocities and not at higher velocities. It is obvious that you have a marginal dimensional situation and increasing the speed of the bullet, in combination with the relatively fast twist, pushed it over the edge, and the bullet stripped the rifling. Before this devolves into another twist pissing match, I have not seen any issues with fast twist barrels, again IF, the bullet and barrel are a good match. If they don't match, twist is just one more small straw than can break the camel's back.

Mike

mike...great info. thanks

p.s. you should have "worlds greatest bullets" in yer tagline...

quote:

and you might have to be satisfied with conventional solid bullets. They have worked for a long time and still do.

Now that is from an upfront guy if I ever saw one!

Not that I want to be loaded down with details, what is the best way of slugging a barrel? It would seem that slugs (lead) would be subject to shrinkage, expansion, or distortion when removed from the barrel. 0.0001"? Seems like this would be tough to measure.

Will,

lead is an inert, non-elastic material, ie it has no "spring-back". If you slug a barrel, you will get as exact a number as you can read on a mike. I know this from slugging a couple hundred single shot and Schuetzen rifles over the last thirty-five years. Slugging is pretty easy, run a moist patch w/gun oil down the barrel and then push a pure lead slug down from the back end with a square nose cleaning jag. If you want to get fancy, LBT makes a "slugging kit" that is invaluable for cast bullets. They make a brass rod that is about .001" under casemouth ID and about half a neck length shorter. They also supply some pure lead cylindrical slugs. You push one thru the barrel from the breech end and get your bore land/groove dimensions from that. The other uses the brass case rod. Put the rod in a fired case and set a slug in it. Chamber the case and run that flat nose jag down from the muzzle and upset it with a mallet. That gives you the throat dimensions.

Rich
NRA Life Member
DRSS

North Fork Mike,
Thanks for taking the time to respond in such detail. Plenty of food for thought there. I might learn something here, eventually.

Has anyone had there mikes checked lately. Measuring to 1 ten thousandth of an inch can be iffy unless in a controled envirement especially with some of the mikes reloaders use

Mike, Rich, thanks for the information!

RIP. .00000633 is the coefficient of linear expansion in carbon steel. That is, the increase of length of any section of the metal in any direction for an increase in temperature of 1 degree F. In a cylinder, the circumference is a unit of length.

Shrink fit temperature calculations are based on a 1 inch bore diameter unit. Working the formula backwards, we get the following:

100 degrees F. .423 diameter
100 X .00000633 X .423 =.0002664 increase in diameter.

400 degrees F. .224 diameter
400 X .00000633 X .224 = .0005644 increase in diameter.

OK math class is over, you can go back to talking about guns.

Dave

RIP. Looked at your calculations, you got it. Guess I'll have to admit to belaboring the point.

Dave