Velocity Extremely Slow

[Cfshooter]

I have noticed one of my 26” 223 bolt guns sent loads much slower than another 26” 223 bolt gun I have. The other day I took both of said bolt guns and a 20” gas gun out and fired the same load with all of them.

The slow barrel was about 140 fps slower than the other 26” and only about 75 fps faster than the 20” gasser.

Any idea of why this barrel is so slow? Is it shot out? I picked it up used so not sure of exact round count, but over 2000 if I had to guess. It does have some copper fouling but even after I gave it a thorough cleaning the last time I tried to figure out why it was so slow, it did not seem to do any to velocity.

The barrel still shoots pretty good though, no noticeable loss of accuracy.

 

[6BRA]

What are you cleaning with? Factory bbl? Freebore and neck differences?

 

[Cfshooter]

What are you cleaning with? Factory bbl? Freebore and neck differences?

It goes through the same cleaning procedure as everyone of my barrel, so no difference is there. I picked it up used but supposedly it is a Bartlein. I am sure the freebore is different than the others, but not enough to make that much of a velocity difference I would not think. I don’t have any other barrels that show that much difference.

 

[GLShooter]

I have shot same lot FGMM 308 stuff through various batches of 20 precision rifles. I have seen the results from barrel to barrel vary as much as 150 fps with same length 24" tubes.

 

[Webster]

I have noticed one of my 26” 223 bolt guns sent loads much slower than another 26” 223 bolt gun I have. The other day I took both of said bolt guns and a 20” gas gun out and fired the same load with all of them.

The slow barrel was about 140 fps slower than the other 26” and only about 75 fps faster than the 20” gasser.

Any idea of why this barrel is so slow? Is it shot out? I picked it up used so notView attachment 1523839View attachment 1523840View attachment 1523841 sure of exact round count, but over 2000 if I had to guess. It does have some copper fouling but even after I gave it a thorough cleaning the last time I tried to figure out why it was so slow, it did not seem to do any to velocity.

The barrel still shoots pretty good though, no noticeable loss of accuracy.

All 3 of your images show some erosion of the lands. Top the least, 2nd. more, 3rd. the most of the 3. Judging it by how far the lands start from the case mouth. In a sense it increases the free bore. All 3 show what some people call fire cracking in the groves. Keep shooting until the accuracy goes bad. Can you increase the powder charge on the slowest without pressure? I hunted GH with a 6mm Rem with about 2" of rifling missing. It still shot under 1". Whats the touch OAL with the same bullet in each rifle? About 12 years since I took the images.


My rifle maybe 20,000 shots? Correction probably closer to 7000 shots (23yrs x 300?)
At the case mouth. Zero rifling or land grooves.
2nd image 6" from the case mouth.









Nasty area 2" from case mouth. Higher mag. Don't remember. I think the upper half of the image is the grove , lower half the land?

 

[TrapperBR549]

This is probably a dumb question, and yes there is such a thing, but is it possible that it isn't the "barrel" that is slow but rather the chamber is bigger? Could that result in a slower muzzle velocity?

 

[markm87]

This is probably a dumb question, and yes there is such a thing, but is it possible that it isn't the "barrel" that is slow but rather the chamber is bigger? Could that result in a slower muzzle velocity?

I think it could be a part of it. Bore diameter and/or chamber dimensions.

I went through this scenario recently with a 14.5 AR barrel that out shot a 16" AR barrel by 30 FPS.

 

[Cfshooter]

All 3 of your images show some erosion of the lands. Top the least, 2nd. more, 3rd. the most of the 3. Judging it by how far the lands start from the case mouth. In a sense it increases the free bore. All 3 show what some people call fire cracking in the groves. Keep shooting until the accuracy goes bad. Can you increase the powder charge on the slowest without pressure? I hunted GH with a 6mm Rem with about 2" of rifling missing. It still shot under 1". Whats the touch OAL with the same bullet in each rifle? About 12 years since I took the images.


My rifle maybe 20,000 shots?
At the case mouth. Zero rifling or land grooves.
2nd image 6" from the case mouth.

View attachment 1523906



View attachment 1523905


View attachment 1523911
Nasty area 2" from case mouth. Higher mag. Don't remember. I think the upper half of the image is the grove , lower half the land?

Thse are some crazy pics, love seeing what it looks like with that high round count.

Touch is different for all as one is Wylde, the other factory savage and the subject unknown reamer.

I am at the limit with charge with that load in the other 26", not sure i want to add more.

 

[Ned Ludd]

There are certainly potential reasons that one barrel might be slower than another that have nothing to do with cleaning issues. Chasing down the exact difference(s) between the two barrels is likely to be an exercise in futility, assuming that there even are any. In your shoes, I might be tempted to give the "slow" barrel a thorough cleaning that included treatment with a fine abrasive such as KG2 to get the excessive carbon out of the throat and smooth out the fire-cracking just a bit. That's probably the best you can do. If that causes the velocity to increase to close to that of the other barrel, fine, but I wouldn't necessarily be expecting that kind of result. Mainly you would be doing it to get the barrel clean and perhaps to reduce the copper fouling to some extent.

 

[Benchrest Braxton]

There are certainly potential reasons that one barrel might be slower than another that have nothing to do with cleaning issues. Chasing down the exact difference(s) between the two barrels is likely to be an exercise in futility, assuming that there even are any. In your shoes, I might be tempted to give the "slow" barrel a thorough cleaning that included treatment with a fine abrasive such as KG2 to get the excessive carbon out of the throat and smooth out the fire-cracking just a bit. That's probably the best you can do. If that causes the velocity to increase to close to that of the other barrel, fine, but I wouldn't necessarily be expecting that kind of result. Mainly you would be doing it to get the barrel clean and perhaps to reduce the copper fouling to some extent.

polishing and smoothing out a barrel should not add velocity (pressure=velocity). and smoothing out the bore will do nothinh to increase your pressures.

 

[Ned Ludd]

polishing and smoothing out a barrel should not add velocity (pressure=velocity). and smoothing out the bore will do nothinh to increase your pressures.

That's exactly what I said, that I would not expect that result.

 

[Cfshooter]

There are certainly potential reasons that one barrel might be slower than another that have nothing to do with cleaning issues. Chasing down the exact difference(s) between the two barrels is likely to be an exercise in futility, assuming that there even are any. In your shoes, I might be tempted to give the "slow" barrel a thorough cleaning that included treatment with a fine abrasive such as KG2 to get the excessive carbon out of the throat and smooth out the fire-cracking just a bit. That's probably the best you can do. If that causes the velocity to increase to close to that of the other barrel, fine, but I wouldn't necessarily be expecting that kind of result. Mainly you would be doing it to get the barrel clean and perhaps to reduce the copper fouling to some extent.

That was the conclusion I came up with last time I shot it prior to this, but after this time I figured I would ask around here as it still baffles me that it is that slow. Maybe I will find a remage to screw on it until I grab my next 223 blank and move on.

 

[Benchrest Braxton]

That was the conclusion I came up with last time I shot it prior to this, but after this time I figured I would ask around here as it still baffles me that it is that slow. Maybe I will find a remage to screw on it until I grab my next 223 blank and move on.

couldn't you just make a separate load for the slow gun?

 

[Cfshooter]

couldn't you just make a separate load for the slow gun?

Yeah, but already going 2900 with the same 80.5 load in my other 26”, not sure how much more I could get. It shoots good so I will just keep letting it be used as a plinker for my 10 year old. Will keep my eyes open for a replacement barrel.