7mm SAUM Rechamber/Barrel Life

[Azzopardi]

Just had a barrel fall of the cliff at 546 rounds. The barrel was 'KG2'ed' prior to the shoot (3 x 10 shot). Up until the 546 round, it held 1/2 of the X ring. It has shot about 12 to 15, 15 shot matches. Balance were 10's. In the end, when I ran a patch down the barrel, it felt like a gravel road.

The attached photos are after 568 rounds. I patched out the barrel with hoppes and cleaned prior to taking the photos.

Photos starting with 'A' are taken from the action end and those starting with 'M' are taken from the muzzle. The number represents the inches from the starting point.

A-1.0.JPG

A-2.5.JPG

A-3.0.JPG

M-0.JPG

M-4.0.JPG

azzo

[Azzopardi]

Let me do that again.

A-1.0.JPG

A-3.0.JPG

A-5.0.JPG

M-0.JPG

M-4.0.JPG

[ajvanwyk]

Azzo, I'm no barrel whisperer and maybe other, more experienced opinions will be offered... but to me, there seems to be a lot of copper.... I use KG2 but have found KG12 to be better at removing it all.

Albert

[Azzopardi]

G'day Albert,
Copper, that's seams to be the key indicator. When speaking with 2 other 7mm SAUM users in the Cairns club, they had the same pattern when their barrels let go.

What I noticed was, just before it let go, the groups got better and better, refer to the time line below. On Saturday I notice lots of copper so I completely removed it as well as most of the carbon. On Sunday it shot a 60.4 then fell of the cliff the next range. The 3rd range was not that better. All 10 shot matches. Got it home, patched it out with hoppes and shot the photos above.

Time line in order of left to right:
90.8, 90.10, 90.11, noticed copper 2" to 3" in and at the muzzle, Eliminator & KG2 clean, 60.4, let go.

[BRETT B]

Hey Azzo , Hard to tell with photos but looks like a lot of hard carbon underneath that copper in A3 and A5.

[Pommy Chris]

That really does look like a lot of copper. Any pics after a pasting?
Chris

[Audax]

Looks more like rust pitting to me, particularly noticeable in A-3 & A-5. Pitting will do the same as fire-cracking in respect of copper fouling. The muzzle end has quite a different look.

Water base solvents may be good for the environment, but I suspect they may leave amorphous residues in your barrel.

[Azzopardi]

Hey Azzo , Hard to tell with photos but looks like a lot of hard carbon underneath that copper in A3 and A5.

That’s correct mate. The barrel was clean after the clean, how quickly it built up over 3 x 10 shot ranges.

[Azzopardi]

Looks more like rust pitting to me, particularly noticeable in A-3 & A-5. Pitting will do the same as fire-cracking in respect of copper fouling. The muzzle end has quite a different look.

Water base solvents may be good for the environment, but I suspect they may leave amorphous residues in your barrel.

No rust, I’m constantly looking after my barrels due to the humidity in Cairns.

[Azzopardi]

That really does look like a lot of copper. Any pics after a pasting?
Chris

G’day Chris,
None taken prior to the shoot after the pasting and I haven’t JB’ed it yet.

[Azzopardi]

Oh well, there’s more new barrels in the cupboard ready to go, woohoo.

[Pommy Chris]

That really does look like a lot of copper. Any pics after a pasting?
Chris

G’day Chris,
None taken prior to the shoot after the pasting and I haven’t JB’ed it yet.

It might be worth pasting it with something like KG, see if you can really clean it up and try it again, you might be lucky and get accuracy back for a bit longer.
I am also curious about 7mm and moly use. Moly seems to extend my 308 barrels life, I cant help wondering if it might extend 7mm barrel life too?
Chris

[watrob]

If that was my barrel, then the first few inches is the start of fire cracking with carbon laid in with copper on top. Would use a hard nylon brush with a piece of 2" square chucks wrapped around the brush coated in JB Red bore paste . Anywhere from 20 to 50 shorts strokes in the first 5" to 7" of the chamber area. The patch out with Bore Tech Copper remover.

With mild fire cracking carbon gets into the hairline cracks with in turn grabs copper, at close to 600 rounds barrel condition is about right but way to much copper in there. Hoppes is fine but try the BoreTech you will be surprised how good it works. To me that looks like a barrel that has not been cleaned and has just shoot 50 to 70 rounds thru it.

[BRETT B]

Hey Azzo , If it is VERY heavy carbon you can get it out just takes some work. If your going to re chamber I would try it anyway but you will need clean it bare and maybe Iosso may be the only thing that will touch it!! ALL the carbon needs to come out so soaking for a few days may help but all depends how baked on it is.Cap 1 end of your barrel, fill with hoppes to top of the muzzle and cap that end , stand upright in the corner for a week. Capping keeps the solvents from evaporating, this could help soften up the carbon. JB Red does work but only after you get most of the carbon out as its just not abrasive enough if carbon is baked on hard. Saums with 2209 are ANGRY hence require a more sturdy cleaning approach than typical calibres.

[Azzopardi]

That really does look like a lot of copper. Any pics after a pasting?
Chris

G’day Chris,
None taken prior to the shoot after the pasting and I haven’t JB’ed it yet.

It might be worth pasting it with something like KG, see if you can really clean it up and try it again, you might be lucky and get accuracy back for a bit longer.
I am also curious about 7mm and moly use. Moly seems to extend my 308 barrels life, I cant help wondering if it might extend 7mm barrel life too?
Chris

Tried moly when I was shooting F-TR and it reminded me of a lady I used to know; messy and I had to clean up, often.