shot-out barrel
I've just started using a pre-64 Win M70 fwt in .243 for coyote hunting. It's a beautiful old gun which I'd like to keep original and pass down to my kids. I'm using 55 grain ballistic tip ammo with a stated velocity of over 4000 fps. Recently I read that bullets traveling faster than 4,000 fps rapidly wear out barrels. My question is: how fast? I've sighted it in using less than a box of shells. And when huning for yotes I shoot very rarely (unfortunately). Does the rapid wear occur from extended shooting with a hot barrel, or does it also wear rapidly when only shooting once or two shots a day/wk? I look forward to your expertise.
When your only tool is a hammer, all problems begin to resemble nails.
When your only tool is a hammer, all problems begin to resemble nails.
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Unfortunately, at that velocity (4000 fps), throat erosion is going to occur rapidly with any pre-64 Winchester barrel. The early Model 70s in 220 Swift were often shot out with fewer than 500 rounds down the pipe. If you want to maintain that rifle, stop shooting the ultra high velocity cartridges and stick with typical .243 hunting loads. If you want a high velocity long-range coyote rifle, buy a new Model 70 in 22-250.
Bert H.
Real Men use a SINGLE-SHOT!0 -
As usual, Bert is right on target.
Strangely enough, handling high-velocity loads is probably the only area in which the modern Model 70s are superior to the pre-'64 ones.0 -
Since it's only the throat that gets eroded, why not shoot it till the accuracy starts to fall off, then get it rechambered?
"Qui non est hodie cras minus aptus erit" --OVID0 -
Good points all! I would avoid pushing a .243 that hard anyway! You could shoot until it starts to fall off and rebarrel and rechamber to a different round. Personally, I would get myself a cheaper 22-250 and shhot it out before I made a mess of that pre-64. Throat erosion just happens FASTER than barrel/crown erosion, but it is still ocurring at a faster rate further down the tube as well. Some of the more modern powders (Vitavouri comes to mind) do alot of what the older standbys do at a lower temp, so that will obviously extend the serviceable life of such a barrel as well. Most of the new high velocity chamberings have SS barrels, which are harderand more resistant to gas cutting/erosion than the "softer " steels of your pre-64. The later production 220 Swift barrels were stainless steel, and they seemed to have a much longer life than their earlier siblings. When all is said and done though...limit your time between shots to no less than 1 a minute (with an extended cooldown period of around 15 minutes after each 10 rounds) and barrel life will increase trigonometrically.
"When I cease learning...I'm dead"(Me)
"When I was 14 I used to marvel at how ignorant my old man was...by the time I was 21 I was truelly amazed at how much the old bugger had learned in the intervening 7 years!" Samuel Clemens
"History is written by winners"(Patton)
"You get a lot farther with a kind word and a gun than you do with a kind word alone!"(Al Capone)
"There is nothing lower than the human race...except the French" (Samuel Clemens)0 -
have SS barrels, which are harderand more resistant to gas cutting/erosion than the "softer " steels of your pre-64.
In regards to the quote by another poster on this topic, I wonder if that is exactly true. I work with a guy who used to manage a machine shop. One day I mentioned to him about stainless steel being harder than carbon steel. He corrected me and said that was not true.
I said I had read whereas the machining tools for processing stainless steel had to take more abuse than they did when machining carbon steel.
He told me that was only because stainless steel is more "sticky" to work with than carbon steel but SS is not actually harder than carbon steel.
Now I don't know what to think.
Quote "Somehow government decided that the Constitutional Bill of Rights has become the Bill of "Suggested" Rights and are to be rationed to the citizens as the power elite sees fit"0 -
If you have a decent gunsmith in the area why not get him to pull the original pre-64 barrel and install a modern barrel in the same contour. Put the pre-64 barrel on the shelf so the rifle can always be restored to original. That way you can have your cake and shoot the song dogs too. If you don't have a gunsmith you trust, send it to Harry Mcgowen in the Chicago area. He can make you a new barrel and cut it to the same exact contour. 0 -
Thank you all for your response and fine suggestions. One last question: at what approx. velocity does greater wear begin for the older, pre-64 barrels?
When your only tool is a hammer, all problems begin to resemble nails.0 -
I am not aware of any published data that correlates exact barrel life versus bullet velocity. That said, bore wear begins the instant you fire the first bullet through it, and it continues with each successive shot. The faster (and greater pressure) that you push a bullet through the rifling lands, the faster the wear will occur. Other things that contribute to faster wear are barrel temperature, and the chamber & bore cleanliness.
Bert H.
Real Men use a SINGLE-SHOT!0 -
JUST MY .02 WORTH. I KNOW A FEW SHOOTERS THAT SHOT THE .243 QUITE A BIT. THEY USUALY REBARRELED AFTER 4000/5000 ROUNDS, PRAIRE DOGS/CROWS ECT. 0 -
Thanks again for the replies and education. Glad I found out sooner than later. Damn the bad luck, now I'll have to buy another gun!!
When your only tool is a hammer, all problems begin to resemble nails.0 -
Pushing the bullet is a result of pressure and temperature. To get the bullet to move faster, particularly in a short distance- like 23-4", getting the speed from 0 to 4000fps takes exonentially more pressure/temperature. There is nothing magical about 4000fps, it's just that at about that point the curve of the graph plotting velocity to necessary pressure/temperature is really getting steep. At that point the gains in velocity from additional increases in pressure/temperature are slight, and the effect on the barrel steel are increasing at the same rate. If such loads are fired, it is wise to get the barrel temperature back to cool before each shot as possible. It allows that much more heat to be absorbed by the barrel as the shot is being made, so allows for reduced barrel wear. 0
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