Is the CZ 416 Rigby barrel thick enough to bore to .470"? It mikes .736 at the muzzle.

Rich

It will make a real light gun, good for
kicking. My 458HE in the Ruger is .92"
at the muzzle.In enfield .95". If you
load it hairy it will need weight.Ed.

Are you measuring the front sight barrel band too?

The muzzle without the band is only 0.670" on mine.
Too light for a .470, IMHO.

RIP,

you are correct sir! As far as that question I had...never mind!

Rich

Measure the barrel about 2 or 3" back from the muzzle... you don't HAVE to use it that far forward.

short answer
the 416 and 458 (and I belive the .375) have the same contour. at 23", it's a fairly think .458 barrel.

jeffe

okay, 3" back it mikes .706". Still a little spooky boring a hole .475" in it...with .135" for wall thickness.

"Hello Steve (@Bauska), make that TWO .475 barrels.".

Rich

My rule of thumb was always leave at least .200 each side of the hole. I've gone as tight as .180 but thats it.-Rob

but it's ONLY .0085 thinner walls than the 458 would have...

and has a sight island.

i tried to call steve yesterday.. Les was in, of all things, steve wasn't

jeffe

yeah, I know...I tried to call him as well.

And, waht Rob said. Personally, I think the 416 barrel is about 1/8" too thin.

Rich

No, 0.15" wall thickness should be considered minimum.

quote:

Originally posted by ScottS:
No, 0.15" wall thickness should be considered minimum.

scott,
you realize, of course, your position, as normal, is unsupported by fact or proven works?

READ THE FIRST SENTENCE in this thread..
.736
subtract .458
divide by 2

and you'll soon find your position untenable.

again,
(sigh)

the industry accepted minimum (scott, call a BARREL MAKER AND ASK.. this might be a new thing for you) is 1/8" wall ...

but that's frequently ignored ... see savage 99 in .358 winchester for example

jeffe

Man this galls me to say Jeffe; Scott is right! I measured the barrel band, not the muzzle as RIP said. Muzzle is .669" or so, and is only .703" 3-inches back. New barrel or love it as is.

Rich

Rich,
what's your barrel at the muzzle? in .416?
.669?
-.416
______

.244
/2
.122 ... on each side... not even close to what scott said... that's .003 less than 1/8", right? or right at the rule of thumb.


yes,the rifle would be light for a .475, but knock off 3", and you are at .114 for a .475...

heh, EVER seen a double rifle with .150" thick barrels at the muzzle?

jeffe

Jeff,

0.669" - 0.416" = 0.253"

0.253" / 2 = 0.1265"

So your math is flawed, again!

I will concede that an ultra light may have a barrel wall thickness of 0.125", but that is an ultra light contour. My statement regarding a wall thickness of 0.150" was to allow for a favorable (matter of preference) barrel heft.

Regardless of the wall thickness argument you have with me, (0.669" -0.475")/2 = 0.097" is too darned thin!!

By the way, Robgunbuilder suggests a wall thickness no less than 0.200", so you have a larger issue with Rob's recommendations than my own. Here is a quote so you don't have to bother yourself with attempting to read the entire string.

Robgunbuilder said:

quote:

My rule of thumb was always leave at least .200 each side of the hole. I've gone as tight as .180 but thats it.-Rob

quote:

Originally posted by ScottS:

I will concede that an ultra light may have a barrel wall thickness of 0.125", but that is an ultra light contour. My statement regarding a wall thickness of 0.150" was to allow for a favorable (matter of preference) barrel heft.

Scott
rob actually BUILDS guns... you've got what, or did you sell it, a beowolf?

.150 is very large..
the AB 458 barrel, which finishes at .720(ish)..
.720
-.458
.... .131" and it's HEAVY ..

.150 is not realistic, for a .475, or even a .500

for example, the pacnor #6 if you take it full length, is .750..
.1375 a side in 475.. and it is HEAVY


You might re-read rob's post.. his rule of thumb .. rub doesn't build anything smaller than .550,

you state .150 a side as a minimum.. in a sub 50 sporting rifle, that's just too dang heavy. It's nto an "ultralight".. no person on this forum will say a cz 458 lott is an ultralight...

So, please, Scott, would you actually post pictures of the DGR 22 you promised to build?

jeffe


Perhaps your beowolf barrel is .150" thick...

Rob build real guns alright and he recommends a barrel wall of 0.2" Jeff!

I sold my 50 Beowulf to a gentleman from Tennessee. It was a real bad ass big bore though

Have a nice day and keep up the good work.

Scott,
Sorry to hear you don't have a big bore any longer. Rob builds guns that MUST be 12#+.. and taking that advice, yep, a .200 is a great idea.

building a 475 caliber, that should be 9.5 to 11, users choice, a MINIMUM of .150, as you suggest, makes a gun too heavy from the field.

Don't worry, it all takes time to learn and take out and use to get it... and .150 certainly is safe, but perhaps impractical

I agree, the beowolf is a nice big pistol class round. essentially a 45/70 class thing.. big hole, for sure, but not a 4000+ft/lbs class rifle (375 HH)

jeffe

Cliff LaBounty told me once that many of the English double guns he was sent for reboring were as thin as .080 at the muzzle (bottom of groove to outside wall). Needless to say, there was no room to grow but it is how they refined the balance so well. It is also one of a few reasons why they get damaged with monometal solids; not enough wall thickness to take the stress.

Hey Jeffe, my 458 AR is .715 at the muzzle of my 24" #5 Shilen. Finished out at 9-9.5 lbs.

.715 - .458 = .257 / 2 = 128.5

Pics

I guess it works fine for me. Now if I were up in the 550 arena there would be more barrel to be sure.

quote:

Originally posted by tiggertate:
Cliff LaBounty told me once that many of the English double guns he was sent for reboring were as thin as .080 at the muzzle (bottom of groove to outside wall). Needless to say, there was no room to grow but it is how they refined the balance so well. It is also one of a few reasons why they get damaged with monometal solids; not enough wall thickness to take the stress.

That is thin indeed, even for a British double. I measured a .465 Holland not long ago that was .086". Most of the British guns are .090" to .100". A min wall of .125" is too thick for a DR.
-----------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

FWIW, the SIGARMS Mauser 98 Magnum in .450 Dakota has a muzzle diameter of only 0.670" at the 25" muzzle. This is treading on thin ice, but it is sporty for a bolt action: 0.106" walls at the muzzle.

0.125" wall diameter at the muzzle is an accepted minimum in some circles, for bolt actions. Heavier is better for sutained accuracy in prolonged rapid fire, considering barrel heating sensitivity of the skinny barrels.

Free-floated accuracy will be better with the heavier barrels too, hot or cold.

My .375 H&H has a 0.625" muzzle at the 24" point. that is 0.125" wall thickness, in the grooves. I would go no thinner.

EVER seen a barrel burst? They do it from the muzzel pealing back. 30Kpsi in a double rifle is a far cry from 65 Kpsi in a .600OK. I've always been very conservative and I was taught by an old New Jersey gunsmith (Mr. Selner who I worked for, for three years while going to college)who always said .200 each side of the hole. He built probably a thousand guns in his career and never to my knowledge had a single complaint! His teachings have never never failed me. However, its more myth than actual expoerience. I suppose you can calculate the actual muzzel pressure for any given cartridge and barrel length and figure out a safe limit. I'd never consider anything less tan .100 . I.m sure you can go smaller. just how far is unknown territrory and someplace I don't want to go. Barrels are cheap why skimp? I also don't really like reboring. Too many opportunities for a bad outcome. Again new barrels arde cheap why take a risk here? I also kinda like barrel heavy guns. They swing beautifully on running game.-Rob

Jeff,

quote:

Sorry to hear you don't have a big bore any longer. Rob builds guns that MUST be 12#+.. and taking that advice, yep, a .200 is a great idea.

I may still have a big bore or 5 laying around.

I think mr Selner had the right idea; .200" sounds just about right to me, and there is plenty of for end wood on the CZ to take a larger barrel. At the dognut for the real sight it mikes nearly .950". A 550 Gibbs would look good tapering to .900" at the muzzle in a 25" barrel.

thanks Rob, et al

Rich

Idahosharpshooter,

A 0.900" muzzle 505 Gibbs would be a tad (way) barrel heavy, in my opinion. Something around .800 to .805 would be best, again in my opinion. It is afterall your rifle though so you build it the way YOU want it! That is the true beauty of custom rifles!!

My .505 Gibbs is .905 at the muzzel band. Weight in the barrel on a heavy kicker is a good thing as you'll find out for yourself. Too bad my .505 is too damn beautiful to shoot. One piece of advice. Build working guns not masterpieces. then you can shoot the crap out of them and have fun. Kinda like hot rods vs show cars. Much more fun.-Rob

Rob,

my favorite rifles all have dents and dings and shiny spots that tell stories. My friends know that if they see an un-marred rifle at my house it is:
a. somebody else's.
b. brand new.
c. taken in trade and getting ready for a little abuse.

Agree with you 100% on the barrel dimensions.

thanks again

Rich

Just for the exercise, I mic'd my Verona O/U 30-06 at the muzzle because I thought it would be as thin as anything I have. Boy, was I right!

Muzzle was .444 on a .308 bore, leaving .068 per side!

My Merkel 141 8x57jrs is .488 at muzzle that makes the walls about .0825. They really LOOK thinner. Never really thought much about it before but if it LOOKS too thin it probably is in my opinion.

Zim,

that 8x57R is probably in the low 40K PSI range, that makes it look a lot better to me than an 8mm Remington Mag would in that rifle...please don't rechamber it, ok?

Rich
DRSS

I believe it's better to maintain some ratio, as such...the thinnest 30 cal barrel I have has a 1/8" thick, so the ratio of .125/.308=.405 so a .475 caliber should have a minimum thickness of .405 X 475= .192....pretty close to what Robgunbuilder has predicted.

The muzzles on my 470NE double mike out at .750" if that helps!

quote:

Originally posted by MacD37:
The muzzles on my 470NE double mike out at .750" if that helps!

(.750" - .475)/2 = 0.1375" wall thickness in grooves.

The strength of that Merkel is beyond doubt, and makes it balance well with a little weight added inside the buttstock, comes out at about 10.5 lbs. for a .470 NE double. Good.

I think that is a perfect muzzle diameter for any bolt action .475 caliber rifle as well, like my .470 Capstick and my .470 Mbogo, which are both .750" at the muzzle.

This allows a 9.5 pound M70 or standard Mauser and a 10 pound Magnum Mauser with similar wood and barrel, bare weights. Add a tiny scope, rings, and ammo and they become about 11 pounds and 11.5 pounds respectively. I would want them no heavier.

Take the fat barreled old Ruger RSM in .416 Rigby, 24" barrel with .810" muzzle:

(.810" - .416")/2 = 0.197"

This is too fat a barrel for a general use .416 Rigby! It weighs about 10.75 pounds bare weight, and if you add 4 rounds of ammo, Ruger rings, and a 2.5x Leupold, you are at about 12.5
pounds. Use a scope any heavier than the midget scope and you are well over 12.5 pounds. No thanks. It is muzzle-heavy. Ruger changed it to a 0.750" muzzle with a 1" shorter barrel and dropped the bare weight down to 9.5 pounds, as the market demanded: 0.167" wall thickness in the grooves at muzzle.

The bigger bores do not have to be kept proportional to the smaller bore wall thickness. The bigger bores will be proportionally stiffer with the same wall thickness as the bore size increases, seems to me.

My BRNO ZKK 602 (bolt action) .500 A2 has 0.180" wall thickness with a 0.870" muzzle diameter for the 23" long barrel (straight taper). It weighs 10.5 lbs. bare.

My Ruger No.1 (single shot) .500 A2 has 0.245" wall thickness at the 1.000" muzzle diameter of the 27" long barrel (straight taper also and not much taper for sure). It weighs 10.5 pounds bare and is the same overall lenght as the bolt action. Perfect.

Muzzle diameter and barrel taper and length should be chosen within the needs to balance the gun at that desired barrel length, for a well balanced and sporty piece that is not so heavy as to take the liveliness out of it.

Take home message: 0.200" wall thickness on everything does not work and is undesirable sometimes.

0.125" wall thickness is enough on .375 caliber and larger rifles.

Heavier barrels than that are a matter of taste, recoil intolerance, other special requirements, AND the owner is an accomplished "gunbearer" for those all day jaunts with rifle in hand.

when I moved to Idaho in 1978 I did not have the AR forum for guidance. That left me to pack a 35" barreled eleven pound Hawken rifle around hunting for a couple years before I read that it was too long a barrel to negotiate in thick timber, that it was too heavy to pack 10-14 hours a day (no sling) and that the crescent butt plate would cause permanent damage to my shoulder system. Oh yeah, and that a puny .520" diamter roundball simply did not have enough energy to kill a pine marten past 25 yards. On the other hand, I did manage to kill every elk I shot at, along with deer, both types, and one antelope a little over 100yds away for four years. What a waste of time...

The exposure here also left me wondering how the average soldier in the 1870's, at 5'7" and 140 lbs packed a springfield trapdoor rifle hundreds of miles chasing indians...?

I will be packing a 10+ pound rifle next summer for buffalo, zebra, and antelope...somehow I will tough it out packing that brick about the Lemco hunting area of Zimbabwe.


Rich
DRSS

Yep,
11 to 11.5 pounds field ready with scope ammo and sling is cool, or a 10.5 pound double rifle that balances and swings like a shotgun is cool.

It is just those 12.5 to 14 pound field ready .416 Rigby's and .577 T-rex's that are a bit tedious at the end of a long day.

thanks RIP,

that was my thought; eleven-five, loaded and slung over my shoulder.

Rich
DRSS

quote:

Take the fat barreled old Ruger RSM in .416 Rigby, 24" barrel with .810" muzzle:

(.810" - .416")/2 = 0.197"

This is too fat a barrel for a general use .416 Rigby! It weighs about 10.75 pounds bare weight, and if you add 4 rounds of ammo, Ruger rings, and a 2.5x Leupold, you are at about 12.5
pounds. Use a scope any heavier than the midget scope and you are well over 12.5 pounds. No thanks. It is muzzle-heavy.

If you bore it out to .475, it'll only weigh a hair over 12lbs, including 4 rounds of ammo, Ruger rings and a 3x Leupold.

Cheers,
Canuck

quote:

Originally posted by Canuck:

quote:

Take the fat barreled old Ruger RSM in .416 Rigby, 24" barrel with .810" muzzle:

(.810" - .416")/2 = 0.197"

This is too fat a barrel for a general use .416 Rigby! It weighs about 10.75 pounds bare weight, and if you add 4 rounds of ammo, Ruger rings, and a 2.5x Leupold, you are at about 12.5
pounds. Use a scope any heavier than the midget scope and you are well over 12.5 pounds. No thanks. It is muzzle-heavy.

If you bore it out to .475, it'll only weigh a hair over 12lbs, including 4 rounds of ammo, Ruger rings and a 3x Leupold.

Cheers,
Canuck

Z-hat says .250" larger than the hole so at .810" you can rebore to 510 for a 500-416 Rigby or 500 Mbogo or even a 550 magnum/550 Gibs

Canuck,
Pretty cheeky of me, eh?
Fred Zeglin agrees with me, eh?
Remember when you taught me to spell "eh?", eh?

I like Fred.
He wrote a neat book on wildcats and gave the 470 Mbogo a whole page.

Fred should rebore "Ol'Purple," the most accurate .416 Rigby in the world,
to .510 caliber.
I need a third 500 Mbogo made from a rebored RSM.

Does Fred do the rebores himself? ... Headed for his website now ...

quote:

Originally posted by Robgunbuilder:
My rule of thumb was always leave at least .200 each side of the hole. I've gone as tight as .180 but thats it.-Rob

Wow this thread was brought back from the dead! I do have a question that has been burning ever since I read this post in 2006: Rob, using your rule of thumb would mean that a 308 would need a muzzle diameter of .708".

Seems pretty dang heavy.

Does your rule only apply to big bores?