I am thinking of using a M70 in 375 to make a 404J (375 IMO is too heavy anyway at 9.25 lbs). What kind of wall thickness is required for such a task?
I rebored another M70 in 375 to 416 a year ago and the barrel thickness is still .168 to the lands so going up to 423 from 416 should give me enough what do you think? What I've heard before is .100 in. is enough which if I did the 375 to 423 I should have .160 in. barrel thickness.

I forgot a very important item. I cannot rebore a 375 H&H to 404J, the shoulder on the 375 will not allow me to rechamber, I'll have to get a new barrel, or make it a 458 Lott.

Min wall of .160" is plenty. Some large bore Nitro Express double rifles are half that.
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"Serious rifles have two barrels, everything else just burns gunpowder."

most palces won't go less than .100 per side... TOO HEAVY in most cases.

A minimum of .125" wall thickness in the grooves at the muzzle of the rifle is a rule that many of us live by.
Many do not.
That is why antique double rifles begin to show the rifling on the outside of the barrel, or bulge or split their barrels.

My .375 H&H with a .625" muzzle diameter satisfies this perfectly, and it will shoot 3/4 MOA for three shots. It weighs 6.75 lbs with a 1 pound stock and an M70-Pre-64 action, perfectly balanced.

.125" wall thickness does not make for a heavy rifle in any caliber, if proper balance is observed.

Accuracy problems and strength problems will be avoided if you go .125" or bigger.

Depends mostly on the material specification. Make your barrel out of Bubba brand 4130 generic imported steel with unknown specification and you better make it phatt! Use something more serious then you can do pretty much anything (if you have the $$$$ of course).

Get the dope on your barrel makers material and get the certification. Do some hoop and radial stress calculations to be sure.

quote:

Originally posted by RIP:
That is why antique double rifles begin to show the rifling on the outside of the barrel, or bulge or split their barrels.

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"Serious rifles have two barrels, everything else just burns gunpowder."

A minimum wall thickness of .125 at the muzzel has been the accepted std for many years. given the muzzel pressures of many of our beloved big bores, this did and does continue to make very good sense.-rob

Many thanks guys for the imput. I've decided to make it a 458 Lott which I'll end up with a barrel thickness of .128 so it should be strong and well ballanced and I'll be using my original hammer- forged Win. barrel for Danny Pederson to cut and rechamber. Rifle should weigh in at 8.5 lbs but I'll be shooting it at reduced velocities around 2150 so I won't be seperating my AC joint in the near future.

Dirk

quote:

Originally posted by 400 Nitro Express:

quote:

Originally posted by RIP:
That is why antique double rifles begin to show the rifling on the outside of the barrel, or bulge or split their barrels.

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"Serious rifles have two barrels, everything else just burns gunpowder."

Oh yeah,
I forgot to mention the weaker, lead containing old barrel steels of the antique guns that were heavier than modern steels for any given wall thickness of barrel.

Weaker steel in a thinner barrel = rifling showing on the outside of the barrel, splits, and bulges, etc.

Dirk what is the price difference between boring out your existing barrel and just buying a whole new barrel? ie. why choose one way rather than the other.
Peter.

Pacnor's number 5 is the same profile as the factory 375 H&H model 70. That is what I used for my 470 capstick and I had them do all the work. Best and quickest $450 I have spent on this project. Made a matched pair in 375 and 470 stainless. Now if I can just get back to Spokane to pick them up from the Biesens with thier new stocks

Peter,
I can get my Winchester barrel rebored and chambered for 250.00. Plus, the barrel steel is hammer-forged thus making it a good barrel to rebore.

If I were to buy a good barrel for the work it would start at 250 dollars. I've had Danny Pederson rebore and rechamber three rifles to date, if they were not good shooters they became good shooters after his work, all sub-MOA with 3 shot groups.

Dirk

I'd agree with a .125 minimum thickness after 20" of barrel.......

quote:

Originally posted by Peter:
Dirk what is the price difference between boring out your existing barrel and just buying a whole new barrel? ie. why choose one way rather than the other.
Peter.

a rebore and rechamber is about $220 bucks, and it fits your stock as well before as after.

a new barrel is about 180, +chamber+stock work.

and if you have sites, or anything "cool" about the barrel, the price of duplication is offset.

and, if you have a 30-06 and rebore to 9,3x62, you have done the world a service

I am doing a post 64 Safari express 404 Jeffery.

The best I can determine the contour is listed by Lilja as a win375b contour. The muzzle I beleive is .750 but they show .720 at 24 inches. The chamber end at 1.220 which is correct.

quote:

Originally posted by jeffeosso:
...and, if you have a 30-06 and rebore to 9,3x62, you have done the world a service

Jeffe,

Don't insult one of God's Chosen Cartridges (the other two being the .338 WinMag and the .375H&H!)!

George

I'm with George on that one...as much as I like the 9.3x62, I still like the 06 better. It will do it all...

I don't understand the thinking of having a light big bore? I want that barrel weight to steady my aim fast and the swing on running shots. The light rifles bounce around and are slow on target after you make a short run.

All for a couple of pounds, go on a diet and lose the extra pounds or do some weight lifting prior to your hunt.

Ray,
I do like a rifle a little barrel heavy myself and totally agree with you on the benefits of it. I don't want to come across like I'm tooting my horn. FYI, as far as losing some pounds or doing some weight lifting, an AMEN to that, I am 6 foot tall, weigh 175, and workout five days a week with weights, bike, run, and speed hike 5-7 14,000 ft. peaks every summer in Colorado. I just still prefer a light weight rifle for caliber.

quote:

Originally posted by jeffeoso

and, if you have a 30-06 and rebore to 9,3x62, you have done the world a service

................You da man Jeffeoso

McGowen/local gunsmith was suppose to make my 458 barrel 0.1" wall thickness at the muzzle but someone pussed-out along the way. The muzzle diameter is 0.778", giving a wall thickness of 0.160". But the rifle should still turn out about 7.8 lbs.

They did test fire it to see if it would blow up! These guys are living in the deep, deep past.

I see no virtue in heavy rifles.