I am considering boring/rechambering a rifle barrel from .375 H&H to .458 Lott.

It is a Browning Stainless A-Bolt Stalker with synthetic stock.

The barrel measures .785" at the muzzle and is 24" long.

If my math is correct, that would leave .163" barrel thickness at the muzzle.

Is that plenty of barrel?

thanks,

Rich

Unequivocally yes. Rule of thumb is .125. I have seen as little as 0.085 that didn't fail either. When they do its like a banana peeling back from the muzzle. Really depends on muzzle pressure, but from a .458 lott, no issues. -Rob

May I watch you shoot it the first time?

quote:

Originally posted by lawndart:
May I watch you shoot it the first time?

Charlie,

Knowing Rich, I suggest that you stand well back if you do!

465H&H

quote:

May I watch you shoot it the first time?

Yes, from a distance :-)

quote:

Originally posted by Robgunbuilder:
Unequivocally yes. Rule of thumb is .125. I have seen as little as 0.85 that didn't fail either.-Rob

+1


There are factory rifles with .100 per side that have been in use for decades.

.100 is a pretty good rule of thumb in your standard cartridges. Some of the lower pressure stuff you can go thinner.

You guys are funny. You get all scared to fire a rifle with a muzzle wall thickness of .125" or .100" yet many of these same nervous nellies think nothing of picking up a Rem 700 with factory sights and firing it.

Under that rear sight the barrel thickness often measures a mere .070" at the bottom of the screw hole. This is maybe 6" ahead of the receiver,if that, where the pressure is still pretty high. Yet, you get all nervous about the thickness at the muzzle being darn near twice that at a point where the pressure curve is at its lowest.

Silly boys.

quote:

Originally posted by z1r:
You guys are funny. You get all scared to fire a rifle with a muzzle wall thickness of .125" or .100" yet many of these same nervous nellies think nothing of picking up a Rem 700 with factory sights and firing it.

Under that rear sight the barrel thickness often measures a mere .070" at the bottom of the screw hole. This is maybe 6" ahead of the ,if that, where the pressure is still pretty high. Yet, you get all nervous about the thickness at the muzzle being darn near twice that at a point where the pressure curve is at its lowest.

Silly boys.

That is good to know.

I had thought so, but thanks to all for the advice.

Lawndart; I am expecting you to fire the first three proof loads, followed by my good friend 465 H&H!

quote:

Originally posted by z1r:
You guys are funny. You get all scared to fire a rifle with a muzzle wall thickness of .125" or .100" yet many of these same nervous nellies think nothing of picking up a Rem 700 with factory sights and firing it.

Under that rear sight the barrel thickness often measures a mere .070" at the bottom of the screw hole. This is maybe 6" ahead of the receiver,if that, where the pressure is still pretty high. Yet, you get all nervous about the thickness at the muzzle being darn near twice that at a point where the pressure curve is at its lowest.

Silly boys.

Yes, good to know.
McGowen barrels wanted to use a barrel band front sight for a similar reason, not wanting to screw into .15" of barrel. The rear sight was no problem because it sits on a "CZ" style island.

Sam and I were testing a pretty thin 458 caliber barrel back a few months ago...... This one is pretty thin, I would not recommend going this thin, but it does make for a VERY LIGHT WEIGHT rifle



We were doing some test work, and even shot oversized STEEL bullet down the bore..........

We hacksawed this section of barrel out to study..... and get accurate measurements....





This is PRETTY THIN.... Damn near thin as piss on a rock!

I once saw a rifle built by one of the great gunsmiths that had a rear sight hole that got drilled a lil too deep I.e. through the barrel about 2 inches from the physical end of the chamber. The great gunsmith fixed the problem by tapping the hole and lock tighting in a set screw. A slighly short screw to hold the sight on and wahla! Another big payday!!! I Only found it by accident using a bore scope. Gun was actually quite accurate and after the residual bullet brass filled the hole was darned near impossible to find. Some Boo Boos rant all that painful!-Rob

My Zastava Mauser in 458 Win Mag measures .625" at the muzzle. That's a wall thickness of .0835"

Interesting article from 1955 on barrel thickness, including pic of rifling impressed thru to outside of barrel (which was a topic on this site ages ago). Starts on page 16.

http://www.gunsmagazine.com/1955issues/G0255.pdf

And a link to more of the classic magazine issues.

http://gunsmagazine.com/classi...s-magazine-editions/

[QUOTE]Originally posted by michael458:
Sam and I were testing a pretty thin 458 caliber barrel back a few months ago...... This one is pretty thin, I would not recommend going this thin, but it does make for a VERY LIGHT WEIGHT rifle



We were doing some test work, and even shot oversized STEEL bullet down the bore..........

We hacksawed this section of barrel out to study..... and get accurate measurements....

michael458;

I love these kind of post and I admire guys like You that get into this experiences, somebody has to do !!! remembers me Mr. Ross Seyfred cutting rifle barrels on velocity tests (Guns & Ammo Magazine)
Thanks for sharing !!! My major concern will not be how it will stand the pressure, but bring an aceptable grade of accuracy.
Kind Regards
G.

quote:

Originally posted by Robgunbuilder:
I once saw a rifle built by one of the great gunsmiths that had a rear sight hole that got drilled a lil too deep I.e. through the barrel about 2 inches from the physical end of the chamber. The great gunsmith fixed the problem by tapping the hole and lock tighting in a set screw. Rob

Rob, why won't you name the gunsmith?

And here I was thinking that one needed .1000" thick walls for safe shooting...

For max double-base powder 458 loads you need more than .085"
thick walls at the muzzle, because pressure down the barrel
is higher. like .140", for max 458 safety. Double-base hot loads
can nearly double the muzzle pressures.
On my 585 I like about .180" min thicknes. When you check less than
these measurements in the hoop strength formula,
you see why this much is needed.And extra barrel wweight helps take
up recoil.Ed

quote:

Originally posted by hubel458:
For max double-base powder 458 loads you need more than .085"
thick walls at the muzzle, because pressure down the barrel
is higher. like .140", for max 458 safety. Double-base hot loads
can nearly double the muzzle pressures.
On my 585 I like about .180" min thicknes. When you check less than
these measurements in the hoop strength formula,
you see why this much is needed.And extra barrel wweight helps take
up recoil.Ed

So if I am getting this...
.180
.180
+.585
_____
.945" outer muzzle diameter.
You might just as well go one inch Ed.

I am sure my friends on here who are gunsmiths might have an insight into this.

I heard of a 416 Remington blowing up in Africa. The reason apparently was that the custom made rifle had the flutes cut too far back over the chamber.

Personally I have never seen anything like this. But the information I got was that the flutes did not stop until they were at the chamber!

Oh boy! Like a fluted Winchester M70 Featherweight contour that was set back even farther than ridiculous!
Gunsmith fluted it, chambered it, then had to cut off the barrel threads and re-chamber it again and again ...

I like to keep the cylindrical breech knox form at least as long as the chamber.

And does Dan Lilja start his fluting about 6" from the breech and end it about 3" from the muzzle?
I will go measure that ...


The Dan Lija fluting at muzzle end, before cutting down to 26" length:



I subscribe to the Minimum-of-0.125"-muzzle-wall-thickness-in-the-groove school of thought.
Add 3 contour numbers to the minimum plain-barrel contour if you want to flute it.

Though I do have one .510-caliber with a muzzle diameter of 1.000" at the 27" muzzle, and it is a straight taper from the 6"-long, 1.2"-diameter breech knoxform cylinder.

That one could use some fluting.

DR- Yes I make the 585s .95 to 1.00".
You read report of fellow in TX with 585 on
a NEF he go from me, running pet load of 650gr
at 2400 and he said it shot real comfy.
Heavy barrel little extra in the butt and thick
pad and you have recoil comfort. and no worries
about barrel bulges.On other forum a guy bulged skinny
shot barrel on an old classic Kreigoff O/U with our
12ga sabot developing loads. And we tell them that
you must have certain minimum for slug/sabot loads
It is easier to leave metal on for right thickness than
having to add more.Ed

I like Dan Lilja barrels, and use quite a lot of them.

No problems with the flutes on the ones I use.

Here is how the 1.350"-shanked .408 No.7 sporter contour barrel compares to the 1.250"-shanked .375 No.6 sporter contour,
regarding fluting.
The six flutes on each barrel are about 0.090" to 0.100" deep.
On these 28" barrels, about 1/2" is cut off the breech and about 1.5" is cut off the muzzle to make a 26" barrel length.

I checked the "Saeed Barrel" aka:
Dan Lilja No.6 sporter, stainless, .375-groove, 1:12" twist, for finish at 26" length.
Assume that 0.5" is cut off the breech, and 1.5" is cut off the muzzle end to finish the 28" supplied down to 26".

As pictured above, below the fatter .408 barrel, the minimum wall thickness occurs in the flute at the 23" barrel length line.
The O.D. of the barrel is 0.775" at 23" length.
The flute is 0.095" deep at that point, might be as deep as 0.100", tough to measure.
So wall thickness in the groove is 0.105" at the 23" length, or as little as 0.100", maybe.

It is thicker everywhere else, including the muzzle with diameter of about 0.750" to 0.755" at 26" length.
Minimum wall thickness in the groove of the last 2.25" of the barrel is 0.1875" to 0.1900".
Thus the barrel is very unlikely to split at the muzzle and peel back like a banana.

Saeed has not yet split his barrel that is only 0.100" to 0.105" wall thickness in the groove and flute at 23" length despite heavy use,
including extensive shooting by Walter and many other hunters and shooters.

My impression is that chrome-moly barrels might be even stronger in this respect than stainless steel barrels.

0.125" barrel wall thicknes in the groove at the muzzle should be plenty strong, for a plain, non-fluted barrel.

That means a non-fluted No. 3 sporter contour cut to 24" maximum length is the minimum barrel contour for a .375-caliber rifle.
That is 0.625" at muzzle. 0.125" wall thickness in groove at 24" length, Douglas No.3 sporter contour.

I do not think any modern barrel maker will supply us with anything slimmer than No. 3 sporter for a .375 barrel, whether chrome-moly or stainless.

I was very happy to find that Shilen supplied a No. 4 sporter contour, stainless, .411" grooved rifle barrel
that will be cut down from 28" length to 650 mm (25.59") finished length.
This will be pushing the envelope.
Will see sometime this year,
400 Whelen Berry of 2013.

thanks for the research RIP.

Rich,
Welcome, my pleasure in measuring the Lilja barrel out of my own curiosity.
Your barrel is about like a No. 6 sporter contour and more than big enough to re-bore to .458 Lott.
You could go on up to .510-caliber.