Barrel Wear

[Graham M]

Back to the subject in hand….as far as shooting out a barrel is concerned, it isn’t so much the wearing out of the actual barrel or the wearing down of the rifling, but more to do with throat erosion that causes the rifle to become inaccurate.

As Mry pointed out in an earlier posting, it isn’t so much the barrel being worn out due to friction but more to do with the throat being slowly burnt away over a long period of time. This is a slow process and something along the lines of the process that happens at waterfalls where the water slowly wears a hole at the base of the fall. It isn’t perceptible but it is ongoing and will not be seen until one day the hole forms into a pool.

The same happens with throat erosion and can take anywhere form 2000 rds to 7000 rds depending on how much powder and how fast the bullet runs.

This process starts from the very first round and continues throughout the life of the barrel. The heat produced from the initial firing is incredibly high and as Mark pointed out last for only a millisecond, but that is enough to give the steel a small abrasive shock that is repeated over and over until a small amount of wear starts to become noticeable as the POI begins to shuffle around.

This isn’t caused by the bullet not spinning properly due to the rifling being worn, but is caused by a process called “Gas-cutting”. This is where the bullet jumps into the rifling over this small area that has been eroded. At first the erosion isn’t enough to cause a problem, but in time the bullet gets to a point where complete obturation isn’t taking place at that point and the gas that normally expands behind the bullet (which is what pushes it up the barrel) suddenly, for a tiny millisecond, finds its way past the bullet and starts to travel up the bore in front of the bullet.

The bullet will of course become fully obturated as soon as it seats itself into the rifling, but the damage has already been done and that small blast of gas is now in front of the bullet, and as it exits the muzzle it acts as a tiny force on one side of the bullet causing it to yaw to one side. This is where the odd flier comes from in a worn barrel.

As time goes by and the gas-cutting gets worse, then the fliers become more frequent until a point is reached where none of the shots will stay in a group at which point the barrel can be deemed to be shot-out.

The barrel can be set back if there is enough material, but in this country this operation is probably in the same price bracket as re-barrelling, which costs as much as a new rifle at times.

Best thing to do is not to run the rifle using “Top loads” with light bullets, but to download slightly and use heavier bullets.

My .243 uses 70grn bullets using 46grns of Hodgden’s H414 instead of 50grns. Only a small change, but the rifle should last a little longer and the foxes can’t tell the difference.

G.M.

[deadeye ive]

 

 

The best life can be expected from the 22 long rifle barrels with 5000-10,000 accurate rounds to be expected.

That is absolute piffle. My Anschutz 1913 has had over 80,000 rds through it and still shoots into the X-ring.

The test rifles at Eley have even more put through them before they are changed.

Blimey, at that rate you would be changing barrels on your .22rf every 12 months.

 

See you fancied a change gemini ...............Out of curiosity why do you think Lilja make this assumption ,Is is to drum up more trade do you think or are they speaking from experience with evidence to back it up from the use of HV'S rds ?

[Graham M]

 

 

The best life can be expected from the 22 long rifle barrels with 5000-10,000 accurate rounds to be expected.

That is absolute piffle. My Anschutz 1913 has had over 80,000 rds through it and still shoots into the X-ring.

The test rifles at Eley have even more put through them before they are changed.

Blimey, at that rate you would be changing barrels on your .22rf every 12 months.

 

See you fancied a change gemini ...............Out of curiosity why do you think Lilja make this assumption ,Is is to drum up more trade do you think or are they speaking from experience with evidence to back it up from the use of HV'S rds ?

Dunno......unless they missed a zero out and it should have read 50,000-100,000 rds. But even then it would be miles off the mark.

Told this story many times and was told to me by Keith Irving who was MD at Eley et the time. A few years ago Eley used 4 rifles on their test range at Witton. They used to change them once they had put 1,000,000 rds through them, but on one occasion someone got the rifles muxed-ip and they change the wrong one. It was only when they came to change this rifle the next time around that it was discovered that it had had 2,000,000, rds through it.

It was still shooting reasonable groups and would have made a nice long-range bunny basher.

The pressures are so low in a .22rf that it is almost impossible to shoot one out in a normal life times use. As I said, my Anschutz has had over 80,000 rds through it since I bought it new in 1988, and it is still shooting as well as it ever has.

Makes me laugh when I see some of the dafter shooters in my club forking out £500 to have a stainless barrel fitted, and then can’t understand why they aren’t shooting any better.

Breaks their little hearts when I tell ‘em its because they have to put the bullet in the middle because the rifle can’t do it on its own. It soon dawns on them that they have probably just wasted £500

G.M.

[Frank]

Ok, about rimfires. From my experience, i have only ever shot one out and that was a semi-auto Brno, an old Brno. I put just over 80,000 rounds threw it using mainly high velocity ammo from new, as the subsonics, seem to jam a lot.

I got the confirmation off a rifle smith, that it was shot out.

Frank.