What makes a barrel quit shooting

J

JRB

Guest
I can see that lapping a barrel, and getting perfect internal dimension will attribute to good accuracy, so what are the effects of barrel wear? why does it quit to shoot?
What happens to the bullet to give inconsistent results on the paper?
Can any of these wear factors be maintained or serviced if you like during the life of a barrel to hold accuracy a little longer?
Jim
 
.

JRB said:
I can see that lapping a barrel, and getting perfect internal dimension will attribute to good accuracy, so what are the effects of barrel wear? why does it quit to shoot?
What happens to the bullet to give inconsistent results on the paper?
Can any of these wear factors be maintained or serviced if you like during the life of a barrel to hold accuracy a little longer?
Jim
Click to expand...


Bore firecracking adjacent to the chamber area of the barrel.
 
All this assuming no mechanical damage caused by cleaning. This leaves excessive wear (e.g., erosion, corrosion etc.)

(1) The throat area,

(2) 2-5 inches up from the throat area, and

(3) the last 2-3 inches of the muzzle (maybe).

Three (3) may only apply to larger caliber, long range barrels. It was reported as early as that BlackStar guy (not the most reliable source), as applying to *some* .30 magnums. It does seem to affect some barrels, but not all.

Now, this may not apply to the "winning edge is over" 6-PPC barrels for international level BR competition (Super Shoot, World Benchrest Chapmionships, etc), where a barrel may start downhill at 250-300 rounds, according to Mr. Boyer. I'm not at that level, so all I can do is report. With these barrels, for this level of competition, I'm not sure we know why.
 
Last edited:
Sorry for being unclear, my meaning is that the group opens up to an unexceptable size, you can decide what that is.

I understand throat erosion from heat and friction, changes the smoothness and diameter of the bore, but why does the bullet not fly to the same point of impact? once this erosion has reached a certain level.
Is the bullet deformed to give inconsistent flight, or is the gas seal behind the bullet inconsistent by leakage?
What changes from shot to shot?
Jim
 
Charles E said:
All this assuming no mechanical damage caused by cleaning. This leaves excessive wear (e.g., erosion, corrosion etc.)

(1) The throat area,

(2) 2-5 inches up from the throat area, and

(3) the last 2-3 inches of the muzzle (maybe).

Three (3) may only apply to larger caliber, long range barrels. It was reported as early as that BlackStar guy (not the most reliable source), as applying to *some* .30 magnums. It does seem to affect some barrels, but not all.

Now, this may not apply to the "winning edge is over" 6-PPC barrels for international level BR competition (Super Shoot, World Benchrest Chapmionships, etc), where a barrel may start downhill at 250-300 rounds, according to Mr. Boyer. I'm not at that level, so all I can do is report. With these barrels, for this level of competition, I'm not sure we know why.
Click to expand...

Charles, you raise some very interesting points
On some older/ hotter and as you say long range barrels, I have noticed some roughness, when cleaning, some work required at the latter part of the barrel. More friction on the bronze brush.
Is this caused by the bullet starting to gain full velocity and thus terminal speed leaves fouling in its wake?
Also I was also amazed when I read of some of the top shooters never go to a match with more that a few hundred rounds on their barrels in fear of them quitting before the match is done.
What do they see, to say the barrel is done shooting? after only maybe 5-600 rounds
if a full inspection was done on one of these barrels, would anything be apparent? or would only a cast slug, show up some inconsistency?
Can any of this lack of accuracy be returned?
Jim
 
Last edited by a moderator:
One of the comments about muzzle end damage stuck a cord.
If a dry patch is first run down my 30BR barrel after a shoot, the normal expected resistance is felt until the last 2 inches where the resistance rises very noticeably.
It feels almost like the bore narrows. When cleaning is complete, the resistance is constant the whole way.
I couldn't guess if this is bore damage (accuracy killer) in the making. Just something puzzling.
 
I'll have to agree that the only thing that actually shows a barrel quit shooting is the target. I've got barrels that look awesome inside, really straight and won't print a competitive group. Then on the other hand, I have a barrel with over 6000 rounds on it that will still print in the mid ones, in competition. I've never seen a barrel look like this inside, there are edges of lands missing, not a fraction of any groove that isn't pitted (way beyond firecracking), etc, etc but I will be more than happy to bring it to a match and let someone shoot it and then look down at it with a borescope. 1980 production shilen 22cal.

The only two visible things I have ever seen that seems to consistantly point to poor accuracy, uneven throat marks on bullets and damaged crowns, outside of that, it's all guess work and both of those problems can usually be fixed.

Hovis
 
HovisKM said:
........ on the other hand, I have a barrel with over 6000 rounds on it that will still print in the mid ones, in competition. I've never seen a barrel look like this inside, there are edges of lands missing, not a fraction of any groove that isn't pitted (way beyond firecracking), etc, etc problems can usually be fixed......

Hovis
Click to expand...




This is such a true weirdness!!!

And Kevin's not the only one to have one of these.

How to explain those barrels that just keep on cranking.

And some for shore DO just that

al
 
fishbone said:
One of the comments about muzzle end damage stuck a cord.
If a dry patch is first run down my 30BR barrel after a shoot, the normal expected resistance is felt until the last 2 inches where the resistance rises very noticeably.
It feels almost like the bore narrows. When cleaning is complete, the resistance is constant the whole way.
I couldn't guess if this is bore damage (accuracy killer) in the making. Just something puzzling.
Click to expand...

This is just what I have seen also,
what is the cause of this?
is that normal or does the barrel need attention in this area?
Jim
 
HovisKM said:
I'll have to agree that the only thing that actually shows a barrel quit shooting is the target. I've got barrels that look awesome inside, really straight and won't print a competitive group. Then on the other hand, I have a barrel with over 6000 rounds on it that will still print in the mid ones, in competition. I've never seen a barrel look like this inside, there are edges of lands missing, not a fraction of any groove that isn't pitted (way beyond firecracking), etc, etc but I will be more than happy to bring it to a match and let someone shoot it and then look down at it with a borescope. 1980 production shilen 22cal.

The only two visible things I have ever seen that seems to consistantly point to poor accuracy, uneven throat marks on bullets and damaged crowns, outside of that, it's all guess work and both of those problems can usually be fixed.

Hovis
Click to expand...

There's always one smart guy!
how will we ever learn anything with reports like this. Ok Ok, I apologise, I guess that is possible, but How??

If none of us know what happens to a barrel to make it quit shooting, why do we just screw another on, and spend all that time and money on getting a new one to shoot, hoping that it will last 500rnds??
Are we missing something?
Jim
 
JRB said:
There's always one smart guy!
how will we ever learn anything with reports like this. Ok Ok, I apologise, I guess that is possible, but How??

If none of us know what happens to a barrel to make it quit shooting, why do we just screw another on, and spend all that time and money on getting a new one to shoot, hoping that it will last 500rnds??
Are we missing something?
Jim
Click to expand...

Accurate rifle barrels are like the tires on your vehicle, one day they are pumped and ready to go, then, suddenly, one day they just go POOF!!

Get used to it, nothing lasts forever, well, maybe "temporary" tax increases??
 
If none of us know what happens to a barrel to make it quit shooting, why do we just screw another on, and spend all that time and money on getting a new one to shoot, hoping that it will last 500rnds??
Click to expand...

Don't know about you, but when I go to a match, I want to win. In spite of all the sportsmanship talk, it's a lot more fun when you win.
 
There are a lot of good shooting barrels screwed off guns at 500-800 rds. But they are not normally tossed. They are kept and when the person gets his new barrels and they won't shoot, these older barrels make a reappearance because at that point, the chances of a barrel that stops shooting during a match is better than starting out with a barrel that isn't competitive in the first place.

I know of a "lot" of barrels tested this year (10ea) that not one was considered competitive. So out came some older barrels until a new batch was received in to try. Just the way it is sometimes. Great barrels will normally start right out that way and then tuning just makes them better. If you have to fight to get a barrel to shoot, that will generally be either a tempermental barrel or one that will flat out quit when you least suspect it and not know why.

Their are a few manufactures of Benchrest Equipment that got their reputation from the BR crowd but once the business gets so big and most of it is outside of BR, then they really don't care about us anymore. It's a sad fact.

Hovis
 
HovisKM said:
I'll have to agree that the only thing that actually shows a barrel quit shooting is the target. I've got barrels that look awesome inside, really straight and won't print a competitive group. Then on the other hand, I have a barrel with over 6000 rounds on it that will still print in the mid ones, in competition. I've never seen a barrel look like this inside, there are edges of lands missing, not a fraction of any groove that isn't pitted (way beyond firecracking), etc, etc but I will be more than happy to bring it to a match and let someone shoot it and then look down at it with a borescope. 1980 production shilen 22cal.

The only two visible things I have ever seen that seems to consistantly point to poor accuracy, uneven throat marks on bullets and damaged crowns, outside of that, it's all guess work and both of those problems can usually be fixed.

Hovis
Click to expand...

One thing that springs to mind, can we learn anything from this old barrel, what are its hidden secrets?
Have you had it since new? if you still own it, what has changed over its life?
Would I be guessing in thinking it is a .222 chamber?

what has been the change in velocity, ES and any other things from new to its worn state?
How many times has it been recrowned or rechambered?
is it possible to slug the barrel to see for any anomalies.
Just food for thought
Jim
 
Charles E said:
Don't know about you, but when I go to a match, I want to win. In spite of all the sportsmanship talk, it's a lot more fun when you win.
Click to expand...

Agreed!
But when the nascar team does not finish the race, does the team engineer say, "The Cars Broke"
Or do they understand why/how its broke?
Jim
 
JRB said:
One thing that springs to mind, can we learn anything from this old barrel, what are its hidden secrets?
Have you had it since new? if you still own it, what has changed over its life?
Would I be guessing in thinking it is a .222 chamber?

what has been the change in velocity, ES and any other things from new to its worn state?
How many times has it been recrowned or rechambered?
is it possible to slug the barrel to see for any anomalies.
Just food for thought
Jim
Click to expand...


JRB.... I hope you get your answer from the source but, while you're waiting, here are my opinions based on my (very limited) experience :)


One thing that springs to mind, can we learn anything from this old barrel, what are its hidden secrets?
Click to expand...
no

what has been the change in velocity, ES and any other things from new to its worn state?
Click to expand...
nothing re velocity/ES, barrel gets rougher feeling (most barrels, once they get rough start throwing shots IME, but not all....)


How many times has it been recrowned or rechambered?
Click to expand...
I recrown when I can no longer shave my nail on the edge of the bore


is it possible to slug the barrel to see for any anomalies.
Click to expand...
IMO, no


These opinions are based on owning ONE long-lasting barrel and knowing of three more, one of which was used at the Super Shoot to good effect

but they are still just uninformed opinions....

al
 
I had a Palma barrel that had groups open up, and just did a recrown, like 1/4" deeper, went back to bugholes at 100. Wrote a PS article about muzzle wear from shooting boattail bullets, and how to fix it. Davey B liked it.....around 2005, as I remember.
 
I got the barrel when buying a used gun. It came with a 6ppc barrel and a 22 waldog. The waldog had 2400 rds on it and shot very good. I put another 300 rds on it. I then had it rechambered to a 22 -.100 short and has had no further work done (no crowning, rechambering, etc). The 6ppc barrel (1980 shilen also) exhibited the same charactorists but when I sold the gun, the 6ppc had just over 2000 rds and was still competitive. I kept the 22 waldog and when I sold the gun, I had the barrel rechambered.

The 22 barrels shot no better or worse than it did before the rechamber.

The barrel has always liked the bullets at full jam. Velocity has stayed the same up to 4500 rds (last time it was checked). At 4000rds, the throat started to erode rapidly (around .040 per 250 rds). Bullets barely stay in the case now. The most notable change was wind drift. As the barrel wore, you could tell the drift in similiar wind increased.

I spoke to Wade Hull about this barrel at the shamrock a few years ago. He said, he had heard a lot of stories about these type of barrels from that timeframe. His opinion was two fold. One, barrel steel was better or at least more consistant (he did say that they have been trying to collect these types of barrels to analysis them) and two, he said, the barrels that they had looked at that seem to shoot better, had a slightly tappered bore and that the bore deminsions as a whole seemed to be on the small side. If I have mistated this, I hope Wade sees this post and corrects me or updates us on his findings.

As far as the NASCAR comparision. There are simulairties. But not really the one you stated. I had a friend who raced the lower truck races (below the old craftsman truck series) and he bought used engines from Hendricks. He would travel down there once a year and buy 2-3 engines. He said that they refresh a good/great engine between races and that they will normally only use one for two races. Why, the fear of failure during a race...kind of sounds familiar with what some top shooter fear about barrels. Also, they build cars in sets of three for the type of track it is made for. They can run the same drive train, shocks, etc in the cars and one of them will always stand out from the others. They look these over and just can not tell why, this also applies to engines. Sounds familiar again. Sure a lot of times they can tell why something broke...so can we, like when a land breaks loose in a barrel, or the chamber is crooked, crown bad, etc. But a lot of times, they are just scratching their heads like we do.

Hovis
 
You must log in or register to reply here.
Back
Top