Throat Wear - Rifling gone, but minimal fire-cracking?

[MikeMcCasland]

Hey Guys,

I want to clarify before I post my question that this isn't a problem I'm trying to solve; more that I'm wondering if my observations are consistent with what others have seen.

That said, I've got a 6.5CM Krieger with ~2,400 rounds on it. The barrel continues to shoot really well, however by round count alone it's obviously nearing the end of its useful 'competitive' life.

I've had to do all the usual things to keep the rifle in tune; I'm up on charge weight about .5gr, and the throat has grown .040" the last time I took a measurement.

Tonight I got some free time on my hands so I decided to clean it up, and I happened to have my bore-scope out; after giving it the usual cleaning I scoped it (last time I scoped it was probably at the 200 round mark) and I noticed something interesting.

I didn't observe much of any 'fire cracking' that I would expect to see with this many rounds, however it looks as though the rifling is just 'gone' from a decent portion of the throat (maybe 1"); it's actually difficult to tell rifling had ever been there.

This leads me to my question...is it common to see barrels that have worn away rifling in the throat, but not to see fire cracking/chucks of metal missing from the rifling?

For what it's worth, it lived off a diet of H4350 almost exclusively.

 

[dnellans]

pictures?

 

[rwj]

.This leads me to my question...is it common to see barrels that have worn away rifling in the throat, but not to see fire cracking/chucks of metal missing from the rifling?

Not in my “relatively” short time shooting rifles...

 

[Dusty Stevens]

Some barrels do not firecrack. Good steel i guess.

 

[300_whisper]

I think you’re over thinking it. Just keep shooting it until it gives up the ghost. Borescopes are your enemy.

 

[MikeMcCasland]

I think you’re over thinking it. Just keep shooting it until it gives up the ghost. Borescopes are your enemy.

I want to reiterate, I'm not trying to solve a problem here; I fully intend to keep shooting this barrel until it gives up the ghost. I'm not going to swap just because of what I see in a borescope.

What I'm wondering about is regarding how common it is to see no firecracking, but rifling worn smooth in the throat.

 

[okie]

I have seen it. A chamber cast will show great detail. I had a hummer .22-250 that lost an inch of rifling and still shot well...2400 rounds

 

[DirtySteve]

I am guessing a slow rate of fire helped your barrel life and prevent the fire cracking.

 

[Doug Beach]

I have a take off barrel, not mine. It’s a Krieger 1/8 6mm, made sometime in the 90’s. It was used on a x-course & prone rifle. I believe it started life as a .243, then was set back, and chambered in 6 International. A piece of tape stuck to it says 6500+ total rounds. The piece of tape also says that it shot well at 1200 yards, immediately before being removed.
There is no visible rifling for at least 3”, possibly farther. Nor is there any apparent char, or cracking, just smooth steel.
They definitely don’t all wear the same way.

 

[billlarson]

When it did quit shooting I would set it back,as much as needed..
OMHO...
bill

 

[AckleymanII]

Look at post #27

http://forum.accurateshooter.com/threads/is-this-barrel-worth-rechambering.3965776/page-2

 

[MikeMcCasland]

I am guessing a slow rate of fire helped your barrel life and prevent the fire cracking.

What's odd is that this barrel wasn't really fired all that slowly.

Best I can figure, feeding it a steady diet of single base powder, and not trying to push 140s to 3,000 may really help with wear.

I shot mostly 142s @2820 and 147s @2800 through it.

That or Dusty is right, and Krieger just had a really good batch of steel.

Maybe a combo of both.

May actually set this one back and rechamber it w/ a shoulder on a savage for fun.

 

[300_whisper]

This might be a dumb reason, so bear with me, do you think that the cracks were filled with jackets deposits or shot so much that the rifling is smoothed out?

 

[MikeMcCasland]

This might be a dumb reason, so bear with me, do you think that the cracks were filled with jackets deposits or shot so much that the rifling is smoothed out?

I can see some cracking; it doesn't look like freshly chambered barrel, but it could easily pass for a barrel with ~300-400 rounds on it (in terms of fire cracking).

I ran some JB through the bore this morning, and I don't think it's jacket material filling in pits. BoreTech Eleminator isn't coming out blue, and the borescope doesn't show anything copper looking.

I guess it's just a magic barrel. It is a 6.5 Creed after all, so this should come as a shock to no one.

 

[okie]

This might be a dumb reason, so bear with me, do you think that the cracks were filled with jackets deposits or shot so much that the rifling is smoothed out?

on mine the rifling is definitely gone--verified with chamber cast. I set it back to a .223 and it still shoots great. The riflings are tapered towards muzzle. Post 11 link explains it exactly with plug? gauges

 

[tmwinds]

I think you’re over thinking it. Just keep shooting it until it gives up the ghost. Borescopes are your enemy.

To late, he's already looked at it...It will never shoot again.

 

[MikeMcCasland]

I mean this lightheartedly, but you guys kill me with your talk about never looking through a borescope; it's pervasive in all borescope threads on here. I can't think of any other aspect of precision shooting that we don't monitor (likely beyond what is reasonable) variables/change etc., yet for some reason looking through a borescope causes everyone to lose their minds.

If anything my confidence is at an all time high; feels like a fresh .250fb 6.5CM chamber to be honest.

Bring on those 150s and 156s!

 

[shoot4fun]

I have a Barlein 6 Dasher barrel that shot a 4.4" age in its last 1,000 yard match in 2016. It has no rifling for almost 5" past the throat.
I did quit shooting it because of that but, in all fairness, it looks like a dried out riverbed.

 

[AckleymanII]

Shoot4fun, you need to go and buy a fist full of lott3ry tickets with your luck!

 

[K22]

My Rem 700, 243, stainless, has a similar condition. I have 3,856 rounds through it, exact count. I have never fired in a rapid succession during range practice and only rarely at game for a follow up shot. During range practice I'm only interested in the cold barrel shot since I'm primarily a hunter so I allow the barrel to cool between shots, i.e. it's rare I fire out of a hot barrel. During the life of this rifle I've used somewhat modest loads of IMR 4350, i.e. 40 grains w/ a Sierra 85 BTHP because this load combo shoots the tightest groups for me. Rifle was purchased new in 1996.

In 2017 was getting some erratic shots and since I don't have a bore scope I had my rifle smith examined the bore with a bore scope as a prelude to a potential barrel replacement. He advised me that there was "noticeable throat erosion but little to no fire cracking. He suggested that I give a thorough cleaning with a copper remover before replacing the barrel.

I was all prepared to have the rifle re-barrelled but decided to perform an extensive treatment with a Bore Tech's copper remover (Cu+2) to see if it helped. I applied it over a period of several days about 30 times. I obtained considerable amount of dark blue patches initially then a "robins egg" light blue color at the end of the process. I'm only recently a convert to Bore Tech products. Throughout most of the life of this rifle I used Shooter's Choice, cleaning every 25 to 35 rounds; apparently it didn't do a great job of removing the copper.

I was quite surprised at the results when I started my winter program in 2018. I was getting five shot groups in the 1 1/2 moa range with no flyers which isn't going to win any matches but is adequate for deer hunting at the ranges I hunt i.e. 200 yards and under.

I know I'm near the end of the life of this barrel but until it shows it on paper I'm going to keep shooting it.