Barrel Flaw or other?

[outlawkyote]

Several years ago I purchased a 7T .224 Shillen 30" and chambered it 223AI.
When it was chambered new the bore scope showed a barrel with impressive qualities and looked really uniform and crisp. The bore scope didnt lie, during load development I couldnt get a group larger that .5MOA and most groups were in the threes and my best group was in the .1s,
For a couple years that rifle shot in the 1s and 2s with ease but recently it has started to open up to the 5s and sometimes 7s.
Im guessing I have 2k rounds through it and it has been taken care of however I started seeing a little alligator scale for about two inches off the lands. Nothing bad, in fact after a thorough cleaning they almost became invisible.

A few weeks ago I decided to set the barrel back a little (1/2") so could rechamber with a new reamer with longer freebore. I had figured I could likely regain some youthfull accuracy by getting fresh lands again. The chamber job went smoothly and the bore scope said I did a great job. The cuts looked very symmetrical with no chatter marks.....etc,etc.
I was wrong, accuracy still suffered but I noticed that the accuracy was great for the first few rounds then progressively got worse.
Back at the house I decided to put the bore scope in the other end of the barrel and was surprised to find a big glob of copper between tow rifeling. About 1.5" from the crown all the way to the crown copper looked caked on.
So what could have happened to my barrel to cause this? I cleaned the copper blotch off and looked for a blemish in that spot but couldnt see anything?
After another trip to the range the blotch returned between the same two rifeling.
I decided to cut 2" off the end of the barrel and recrowned it but havent made it back to the range because of cold weather. Im assuming I got that problem fixed but just cant think what could have been causing it.
As a side note, I have older 223AIs that are looking pretty sad compared to this barrel yet they still shoot lights out.

 

[FisherT&C]

That part of the barrel has probably been worn too smooth. The crown area makes sense because that is where the bullet is fastest in the bore. You may have fixed it with removing that portion, however if your bore is on the low end of the tolerance you may be able to lap it a little and get some life back. You can cigarette roll a cleaning patch on .17 cal brush and use 180 grit lapping compound to scratch it up a little and that may prevent serious copper fouling.

 

[outlawkyote]

I wonder if JBs bore paste would rough it up a little?

 

[flyright]

A friend of mine had an old .223 varmint gun/barrel that shot exceptionally well - .1's pretty regularly. At an estimated 3000 rounds it started to open up to .6-.7's. He cleaned it well and accuracy returned for about 150-200 rounds. Having great confidence in that barrel, he had it set back a couple of inches and re chambered/re crowned. Accuracy was lackluster after that - about 1 moa - so, he had it cut a small amount and re crowned. It still shot about 1 moa. He then had it re barreled and it is now a .2-.3 shooter that he can live with.

Long story shortened - After I watched that process - I'll never mess with that stuff, straight to a re barrel for me. Just MHO.

 

[briang7511]

any chance you could cut the 1.5in off the end and re crown? may not be the length u want but may bring more life to the barrel.

 

[outlawkyote]

any chance you could cut the 1.5in off the end and re crown? may not be the length u want but may bring more life to the barrel.

Yes actually
I cut 2" off the barrel and re crowned it but between having a bad weather weekend and work haven't allowed me to get out to shoot it yet to see if I've cured the problem.
If this doesn't resolve my problem I'll likely have to re barrel.

 

[outlawkyote]

Shot it today. I think its time to re barrel. Still only getting .7"
Well I tried, too bad it was an excellent barrel.

 

[swampbuck]

2k rounds on a 223 Ackley isn't a bad life. I'm with flyright. The cost of machining recrowning and chambering doesn't appeal to me and is cost prohibitive. If you plumb your own then I guess it's worth it.

 

[outlawkyote]

2k rounds on a 223 Ackley isn't a bad life. I'm with flyright. The cost of machining recrowning and chambering doesn't appeal to me and is cost prohibitive. If you plumb your own then I guess it's worth it.

Yeah, I do my own.
Spun the one in question up from a blank and it turned out really nice. Im used to getting 3000-3500 from a 223AI but I might have taken too good of care with this one? I can almost see a reflection on the steel with a bore scope. Maybe need to rough house them a little more?

 

[ajridgedell]

I never had good luck "setting a barrel back". I'll just stick to putting a new barrel when it goes south.

 

[Greg Langelius *]

My approach would be to (piloted) counterbore the muzzle end of the bore down to just past the blemish.

My reasoning; to disturb the barrel harmonics by the absolute possible minimum. A minimum bore expansion and the counterbore will change the bore length, but the barrel harmonics should be very close to the original. The net effect could include some of the benefits(?) of a linear compensator, directing sound more toward the target, allowing some sound redirection without adding a muzzle device, which can be prohibited in some competitions.

Note that the actual physical crown will be at the bottom of the counterbore, and not at the muzzle end of the barrel.

Please note that ths is a totally theoretical proposition.

Greg

 

[Greg Langelius *]

Shot it today. I think its time to re barrel. Still only getting .7"
Well I tried, too bad it was an excellent barrel.

It's probably still a good barrel, but the load is/was optimized for the the original barrel harmonics; or did you redevelop the load already?

Greg

 

[outlawkyote]

It's probably still a good barrel, but the load is/was optimized for the the original barrel harmonics; or did you redevelop the load already?

Greg

I did not re devolp a new load and still waiting on a new barrel. You might be on to something. I will try that and let you know. Its too cold right now though but will try it before replacing the barrel.

 

[Greg Langelius *]

Shorter should, in principle, be proportionately more accurate. But a barrel needs a matched load.