Barrel life...

Like sand through the hourglass, so are the days of our barrels.

I've read quite a lot about barrel life. Most say this or that cartridge will produce X-hundreds or thousands of rounds of accuracy life or something similar. In actuality, each and every shot erodes molecules of barrel steel from the throat or leade. This slowly accumulates over time as more rounds are sent down the barrel.

I got a bit of a surprise the other day when I checked loaded overall length in my 223 with a recently bought box of Nosler 50BTs. Twenty years ago, the same bullet produced a cartridge length of 2.320" when the bullets were seated a couple thou off the lands. I was surprised at the OAL I needed now to get the same land/bullet measurement.

At first, I thought that perhaps Nosler had changed the ogive. So, I pulled out a box of bullets I'd had from 20 years ago (not 50BT) and had used to check/record OAL back then. The rifle is still very accurate - hasn't changed much, but the leade has opened about .030" since the early days of the rifle, some 2000 rounds ago. The varmint weight barrel has been warm quite a few times, but never hot.

For those who want to keep track of leade wear, keep a few bullets to use for OAL measurements on down the road. Or, maybe ignorance really is bliss.... BT

Good summation of common assumptions that are wrong. Thanks for the wake-up, BeeTee.

Yup, I think maybe the ignorance is bliss!

SJB358":130k4twi said:

Yup, I think maybe the ignorance is bliss!

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Agree. Shoot 'em until they don't shoot good anymore, then replace 'em.

Barrels are like tires, even the good ones wear out eventually. A race car is going to wear 'em out faster than a grocery getter...

Gulp, I just realized that I don't have ANY spare barrels loafing around here anymore! I used to keep a couple ready to be chambered and installed... Better get with the program and order up a new tube or two!

Guy

ignorance is bliss! I agree

I think I stopped buying barrels when I was seriously considering re-barreling my .308 to something smaller, like a .260 or a .243... Then I waffled on that... And now I'm waffling on the waffle... Have so much .308 brass and so many .308 bullets on hand... Better order another .308 barrel! :mrgreen:

Maybe two. And a spare for the .25-06... I thought it was done once, but a thorough scrubbing seems to have restored it.

Wish I hadn't re-checked the bullet/land measurement... Ignorance is bliss, in this case. Makes me think that anyone looking at a used rifle should have the leade checked with a borescope before plunking down the bux.

The reality is that it took 20 years to shoot 2,000 rounds (90% of those in the first 5 years). My guess is that the rifle will still be accurate longer than I'll need it to be.

Guy, if I had that much stuff for a 308, I'd stick with it. Add another rifle if necessary, but keep the 308. An accurate 308 is the one rifle I plan to get... BT

I saw a link to SnipersHide about the 6.5 Saum mentioned in another thread here. See post #225 in the following thread link.
http://forum.snipershide.com/snipers-hi ... aum-5.html

There's a discussion about pressure and barrel life that I found interesting. Post #225 summarizes it pretty well. Also in that thread was a discussion about setting back/rechambering a barrel for about $150. This could add life to a well worn barrel that had been very accurate.

BT - yes, I've had barrels set back and rechambered. If a guy catches the barrel early enough, it works well.

Had one Hart that went many thousands of rounds, for two owners, after having each end of it chopped off at least once or twice! That thing started life as a .300 mag bull barrel for 1000 yard prone shooting and ended life as a short, stout, .308 Win barrel. It was mighty accurate too.

Guy

And yes, I'm kind of hung up on the .308 Win. It's been real good to me over the years.

Lots of match shooting with it, mostly in the 1990's & early 2000's. Quite a bit of hunting from varmint shooting to bear hunting. And I carried that rifle on SWAT for about 12 years too. We're sorta used to each other.

Guy

Barrel life is shortened by the intense heat applied to the throat during the very short firing sequence. If you shoot a gun repeatedly so that it gets too hot, then the burning powder has less heating to do in order to get to the barrel burning temp. So letting your barrel cool certainly helps a lot.

Also slower powders spend more burning time at the throat than faster powders. Milliseconds for sure but over 100's or 1000's of firing, it will add up. Hence this chart which should be used as a guideline only



Of course, what happens in a chamber is extremely hard to catalogue and analyze

Is there any good data on accuracy or life difference between stainless and cm steel?

I've heard that stainless will extend barrel life about 10%, but I haven't seen any real data. I also know that stainless is more difficult to machine. Does affect the accuracy potential? BT

No hard data, but it's been a long time since I've seen anything but a stainless barrel on the firing line at a match.

There is a lot of industry study by metallurgists on 400 series (SAE 416, 440C) stainless and Chrome Moly (SAE 4140, 4350) steels for wear on each other and wear by certain friction conditions with other materials. I do not know how much has been done on guns, per se, especially with jacketed lead in rifle barrels. There are some issues with rifles such as, bullet pressure, friction coefficient of that bullet in that barrel and latent heat when fired which makes wear on a particular barrel's life very subjective. I have seen Army Natick Labs studies that say 2000 to 3000 rounds or something, which may be as close as they can predict barrel wear.

I know from being in the Army Infantry that you can cook a barrel in a couple of hours, or less, of sustained automatic fire. Also, I have seen 50 year old Garand's that have been in combat and in infantry unit shooting that look pretty good for barrel wear.

I have read that in addition to keeping it cool, good cleaning procedures extend barrel life. I'm fussy in that respect and so far, although I don't shoot large amounts of ammo the barrels of my most used rifles seem to be in excellent condition and a borescope verification from a member of my gun club let me know that I've been cleaning properly.

My problem is, I have say a .270 Win, Model 70 Super Grade that was made in 1949. I have been shooting it about 100 rounds per year at full house velocity, for 40 years but not so much now. That however, is 4000 rounds with a barrel that I can't replace. Accuracy in that barrel is still sub MOA but is not what it was 20 years ago.

OT3, I don't understand, why can't you replace that barrel?

Not that it needs replacing.

Guy

Well to quote the late great Elmer Keith
"To heck with efficiency, its performance we want!"

I feel the same way about my 6mm-284

Guy Miner":2uocrdo9 said:

OT3, I don't understand, why can't you replace that barrel?

Not that it needs replacing.

Guy

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Guy, I can replace it but not and keep it a 1949 Model 70 Super Grade.

Oldtrader3":3dfeuxya said:

Guy Miner":3dfeuxya said:

OT3, I don't understand, why can't you replace that barrel?

Not that it needs replacing.

Guy

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Guy, I can replace it but not and keep it a 1949 Model 70 Super Grade.

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Aesthetics contra a utilitarian view--there'll never be complete resolution. I see both sides. FWIW, Charlie, I passed on a nice pre-64 .270 because I was looking for a donor and had no desire to destroy a collector's item.