Hand loading for a worn out barrel/ throat

N

Nosler guy

New member
Almost every sportsman/woman is or should be concerned with the barrel life expectancy of their rifles. I say rifles because a man or lady ought to own several. This post is here to help encourage folks that there's a chance that worn out rife of yours that doesn't shoot so well may have some life left.
I have an old and very shot out Mauser. 243 passed down from my grandfather. The throat is so worn that there's no chance of chasing the lands and a 95 gn boat tail bullet just barely hits before it falls out of the case. While first hand loading for this rifle I could still get nice groups, with a lot of effort, but the velocity was a few hundred fps slower than what most data was showing. With a little help from some expert ballistic techs I started finding a solution to getting better velocities and accuracy. Instead of worrying about having too much jump I started seating bullets deeper in the case. Another thought was that a worn out rifle will produce less pressure, which turned out to be the case with this Mauser. In the end I learned that I could seat bullets with literally a quarter inch of jump and fill the case with up to 2 or 3 grains of powder over published max and not only shoot straight but achieve the velocities I wanted, which were usually on the high end of published. Most all of my pet loads are compressed, and powder charges are far over max published and seating depths are far under saami specs but I've had great results and little or no pressure signs.
Now I'd never encourage someone to throw a couple extra grains of powder in and head out to the range. Obviously you need to work up to wherever your rifle shows pressure signs in a safe manner. It took a lot of work and frustration but I firmly believe that there's new life in (most) worn out barrels if you're willing to reinvent the wheel, so to speak.
 
I agree. The rifle mentioned was recrowned by hand with a burr type hand crowning tool. I also forgot to mention that I wanted this rifle in original condition for sentimental purposes. I wanted to use it as my grandfather left it to me rather than rebarrel it, even if rebarreling it may have been cheaper than powder and bullet costs through extensive testing.
 
I get keeping a family rifle, hang it over the fireplace and be happy with it.
I can't recommend continuing to fire it.

There is an option for throat erosion...
I have done it on countless rifles, new with a bad chamber to very old.

First off, don't guess, or use 'Eyeball mk1',
Find an actual bore scope and evaluate the rifling,
If the rifling is decent,
Then pull the barrel, cut two or three extra threads where it threads into the reciever.

This sets the bad chamber back, closing up head space.

You are only losing the thickness of a thread or two in barrel length,
And you aren't swapping out the Origional barrel.

Then simply trim the chamber end the thickness of the threads you added, cut in an extractor grove if your barrel had one,
And RE-chamber the barrel.
This will remove excessive free bore, returning the throat taper to its proper position relative to rifling.

A gun smith will charge about $100 (if he's reasonable) to do the work, since it all gets done in the lathe without repositioning the barrel several times.

I do this ALOT on the current crop of 'Factory' rifles since most factories don't headspace or cut chambers on the lathe, the chambers are often misaligned with the bores, or cut way too shallow or too deep...
 
This was simply a post for folks that have a shot out barrel on a rifle in, otherwise, good working condition. Great info on what can be done at the gunsmith and i sure appreciate the reply. There are some hand loading techniques to bring some barrels with throat erosion back to life without sending it in to the smithy. Also said Mauser was throughly inspected and found to have heavy erosion at the throat. The rest of the barrel, after having been hand recrowned, was in good shape. There's a long list of info out there on what a gunsmith can do to fix your rifle but the list is pretty short on techniques to fix the problem yourself.
 
Only barrel I ever wore out was on my 220 Swift. I had to start chasing the lands and loading heavier bullets, in the hope that the heavier bullets were longer. You long time reloaders already know how that worked out for me. That was my first enlightening encounter with bullet stability and what will and won't stabilize in a 220 with a 1 in 14 twist. I finally decided to have it rebarrelled.
 
I've been there too 603 country. You don't always have the option to drastically change the way you load because some bullets are just too short to do much with. If you ever have a slow barrel, or just want to experiment try seating lower when you're tuning a load. You might be throughly surprised in velocity and accuracy. The only negative effects I noticed with a quarter inch of jump wastart higher sd's, in the 10-18 range with h4350. I usually get sd of 5 or 6 in a Weatherby .243 with that powder. Some bullets like the accubond long range work best with .100 jump or even higher.
 
I can't be too specific, since the model of rifle wasn't posted.
The old 1898 Mauser large ring was plentiful, cheap and the basis for bench rifles for years & years.

*IF* its a '98, then its already got an aftermarket barrel in it since all the actual '98 Maisers were 7.92mm (called 8mm Mauser) from the factory.

I've owned dozens, and rebuilt hundreds of them down through the years,
For what they were, you won't catch me saying a bad thing about them,
Probably the finest military bolt rifle ever made.
The civilian versions were a virtual work of art,
Nothing quite like owning a 'Butter Kinfe' Mauser!

Doesn't much matter what condition a Butter Kinfe bolt handle Mauser is in, when I find them I restore them, just great rifles all the way around.

I say it pretty often,
'I don't have an opinion, I have a bore scope'
If its just the throat, its real simple to set the barrel back two or three threads,
Re chamber the barrel, and it will function/shoot just like new.
Finding an actual 'Gun Smith' is fairly difficult anymore since firearms have gone the way of everything else, disposable.

I try and tell people, when you buy a modern rifle, its a starting point.
The money you 'Save' with a production, off the shelf model is where you START,
Most of them need the reciever squared, threads strightened, bolt lapped in, chamber re-cut & barreled action fitted to the stock.

That puts you up to the cost of a 'Custom Shop' rifle where you should have probably started in the first place.

I look at classic rifles like classic cars,
If you shoot them, you will have to put money into them,
But they aren't making classics anymore, so its more than worth the money!
 
Set the barrel back and use a 105. Won't make up 1/4" but being off the lands isn't necessary anyway.
"...achieve the velocities..." Velocities are not as important as safety and accuracy.
You could re-chamber it to 6mm Rem if the rifling is ok. 419 thou case length difference. Mind you, finding that brass might be problematic.
 
6mm Rem brass hard to find????

Just do what I do for the 257 Roberts... Neck down 7mm Mauser brass...

Problem solved.
 
Nosler guy,

You might appreciate the item numbered "3" of this old web page.

You can, of course, make a rifle shoot like new by setting it back and re-finish reaming the chamber, but if, like the grandfather's rifle described in that link, it shoots better than new with your adjusted loads, then that could be counterproductive. Starting with Franklin Mann's experiments about 120 years ago, many folks have found easier bullet centering in the bore with more gradual leade angles than are standard for their chambers. In his 1998 book, Rifle Accuracy Facts, Harold Vaughn described making his own chamber reamers with throat angles about half what SAAMI has for most rifle chambers at about 0.75°.

A shallow leade angle is, of course, what a worn throat already has. The main problem with worn throats is not necessarily the shallow leade angle or the bullet jump, but asymmetry. This is due to the surface developing an alligator skin-like topography from differential heat stress between the surface and underlying metal (aka, the substrate metal). The little squares of that skin eventually fatigue their bond with the substrate and start to chip off, and that's usually what causes asymmetry. They can break off on one side first, for example.

The main thing is getting the bullets to go straight into the barrel. Being close to or even touching the throat is one strategy for this, but other dynamics like gas bypass complicate it so that doesn't always work best, with many accuracy loads turning out to jump a good bit. This is described in this Berger article.

The Tubb Final Finish product cleans those little squares out and gives you a clean, if slightly elongated throat. David Tubb is, IIRC, 10 times national Highpower Champion, and he says he doubles normal barrel life this way. The advice to use a Borescope (currently on sale at Bruno Shooter's Supply, I believe) is good. It will know more exactly and control how many of the FF bullets need to be fired to clean off the throat. Look near the muzzle, too, as a gun with a lot of rounds through it can start to funnel there and the cleaning marks from the FF bullets will tell you if you have that issue. You can always counterbore the muzzle a short distance if you don't want the outside contour altered by cutting it back.

As to your uneven start pressure, if you haven't already, try deburring flash holes and try a magnum primer (load needs to be worked up over again with the magnum primer). You can also experiment with crimping if you want to. I find it is adequate just to spin a bore brush inside the neck enough to get the surface clean and evenly brush-marked. YMMV, but it's a starting point.
 
UncleNick.
I do very much appreciate it. It was a good read, even if it was a different English he was writing. I do remember seeing the "alligator skin" and it reminded me of bead blasting with glass media. Thank you for the advice and interesting info. If I ever wear out the 300 or seven mags I might have to try this out. And yes I'm mostly aware of the solutions for a worn barrel I just wanted to write something for other folks as stubborn as me. We spent quite a bit of time with this rifle in the nosler lab tinkering and coming up with different theorys on what all was taking place in the chamber.
 
Barrel wear.

Most important-
The main thing is getting the bullets to go straight into the barrel.
Click to expand...
My vintage Rem 40x is well worn, but does well with this method. FL size using a bushing die. Adjust the bushing to only size 1/2 of the neck. The unsized neck area will expand to the chamber, centering the round in the chamber, after 3 firings. Do use a brush when cleaning, to remove carbon/misc fouling that attaches to the fire cracking. There is no need to load to a longer OAL in my 243 Win. Bullet jump works for me.
 
243winxb,

Yes. That's usually called partial resizing. It works better in some cases than others. If your cases have uneven neck wall thickness, partial sizing will still leave your bullet off-center by the amount of neck wall runout. You can improve on it by outside neck turning first, if you are relying on this for centering. There was one example in the Precision Shooting Reloading Guide. The author said he'd never found outside neck turning to make a difference in most of his rifles, but he had one 300 WM that was stuck at 1.5-2 moa no matter what he did until he outside turned necks, after which it became a 0.75 moa gun.

At any rate, if you can find a seating depth your gun likes best for lining the bullet up, then even if your bullet has a little runout, it will correct on the way into the throat. Why that can happen isn't really understood, but not only did Berger find it to be true with VLD's, but that same Precision Shooting book (1995) had a description by the late Dan Hackett of having a 40X in 220 Swift that would never shoot 5 shots below 0.5" and many 5-shot groups were as much as 0.75" from it. He always seated bullet 0.020" off the lands, which was one of the several "right" bullet jump numbers that have appeared over time. Then one day he was switching bullets to a Nosler BT from something with 0.015" longer ogive and turned the micrometer that amount, but in the wrong direction. As a result, Nosler BT was seated to a jump of 0.050" instead of 0.020". He got 20 rounds loaded before finding the error. He considered pulling the bullets, but elected to just shoot them in practice and forget how they grouped. To his surprise, that 20 rounds gave him two 0.25" 5-shot groups and two true bughole groups in the 1's (under 0.20").

You can argue that all that happened what the greater seating depth increased the pressure and shortened barrel time just enough to be on a better sweet spot in the barrel "vibration". The problem with that is that if it were true, he'd have found the same barrel time just by adjusting his charge weight, but he didn't. Same as with Berger's early experience, even though they had people touching the lands for alignment, some guns just wouldn't shoot their secant ogive VLD's well until they backed them up to create some jump. So there's another factor involved. AFAIK, nobody has yet identified it or correlated it to any observation other than tightening group size.
 
"You could re-chamber it to 6mm Rem if the rifling is ok. 419 thou case length difference."

IIRC
6mm chamber will not clean up .243 chamber. .243 is bigger diameter at the shoulder than 6mm at same distance from head. Operation would still require setting barrel back approx .25"(minimum).
 
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