How To Do It Right

[DakotaMan]

[
This is the one I was referring to. Both the groves and the lands still have carbon on them and it should be removed from both. For precision shooting, you don't want this much carbon on these as it deforms the bullet. It is tough to remove and it tends to bake on at the rear (i.e. the back 6-8 inches of the rifling) of the barrel. You got the ring just ahead of the case pretty well. The .308 is that depth in the grove and any amount less than that on the lands that the barrel maker prefers.

I went through this several years ago and finally broke down and bought a tube of Semichrome.

[jhjimbo]

Re: your posted pics. How did they get so many cut marks across the lands. Almost looks like some kind of ccutter was used.
As far as cleaning the groves it would be nice to have a button specific for the barrel to make cleaning much faster.

[jhjimbo]

When I looked up the SemiChrome I recognize the box so I know I have some, just don't know where. Last time I remember using it I had my Mother polishing silver - something to keep her busy. Have to look aorund the china closet.

Started working on the rem 742, .308 one application and it seems half done. BTW, J-B ;makes a different paste for SS. Don't know the difference except it is maroon or dark red. (My tool maker buddy said SS gauls so maybe that is why it is different. (my tool maker buddy used to make the triggers for nuclear bombs at Cherry Hill - he showed me an old funny paper he made one from and honest it looked like it had more edges and sides than a Rubiks Cube)
Muzzle, locking lugs,extractor, ejector

[DakotaMan]

Re: your posted pics. How did they get so many cut marks across the lands. Almost looks like some kind of ccutter was used.
As far as cleaning the groves it would be nice to have a button specific for the barrel to make cleaning much faster.

I always wonder as well when I see bad bores like this. I believe it is a cut rifled barrel and the cutter was chattering as it moved down the barrel. Of course no lapping at all was done either so that left the mess pretty well as is. I've also seen a raised line go all the way around the rifling apparently from a broken tool during hammer forging. You never know what you will find.

[DakotaMan]

Muzzle, locking lugs, extractor, ejector

jimbo, I prefer to inspect the crown from inside the bore. Take a look all around the crown to ensure that the front edge of each rifling land is perfectly square and sharp as a razor. It looks like this one might have severe wear on the leading edge of a couple. That allows high pressure gas to bypass the bullet upon exit, causing the bullet to yaw. I can ruin accuracy.

[jhjimbo]

jimbo, I prefer to inspect the crown from inside the bore. Take a look all around the crown to ensure that the front edge of each rifling land is perfectly square and sharp as a razor. It looks like this one might have severe wear on the leading edge of a couple. That allows high pressure gas to bypass the bullet upon exit, causing the bullet to yaw. I can ruin accuracy.

Two at the muzzle with mirror and two at the chamber with the mirror.

How do they look from the inside? Muzzle and lock lugs

[jhjimbo]

It is slow going. My rifle barrel has a lot of pock marks in the groves. First 3 are rifle. Last two are carbine barrel.

have not started the carbine barrel yet.

[DakotaMan]

[QUOTE=jhjimbo; How do they look from the inside?/QUOTE]
The crown appears to have uneven wear on the rounded fronts of the rifling. It's a little hard to tell in these pictures but the thing you are looking for is uniformity in the front edge of the rifling. Rotate your bore scope slowly all around the perimeter of the crown from inside the bore. Try to observe the depth of the wear and consistency of the shape of the crown. You are looking for any opportunity for high pressure gasses to pass the bullet on one rifling but not the others. On all my precision rifles, I re-crown every 400 shots to keep the crown perfect. For hunting, you need only be able to achieve acceptable 100 yard precision. When your groups seem to be growing, it might be time to re-crown. You can do that with a crowning tool at Brownells.

The lead to the bore looks good... minimal wear. Good luck! Looks like you are having fun with your new bore scope.

[jhjimbo]

I picked up a tub of Semichrome from Amazon and a tube came with it for an additional $3. I have a lot of cleaning to do. I am thinking once I get them cleaned it won't be as hard to keep them clean. Hope I get my order before the storm hits Sunday night to Monday. maybe 3" of snow and cold.

I forgot to ask, do different powders leave different amts of residue ? I know some powder kernel shape is harder on the steel than some of the flake poders.

[DakotaMan]

I Do different powders leave different amts of residue?

I'm anxious to hear how Semichrome works for you. You are right that once you get the bore very clean, it will be easier to keep clean. That is the main advantage of a bore scope. Most of us think that if we cleaned it, it must be clean. As you have shown, it can take a lot of work to clean up a barrel, even after we have cleaned it several times. I'm hoping you will find that Semichrome helps you remove the baked carbon much more quickly.

Different powders DO leave different amounts of residue and your bore scope will help you determine which ones are easiest on barrel maintenance. I've found that having a mirror smooth, lapped barrel really reduced the amount of fouling that any powder produces. I really don't worry about fouling too much in those rifles. However, the blowback carbon on ARs makes me real fussy about what powders I use.

[jhjimbo]

I'm anxious to hear how Semichrome works for you. You are right that once you get the bore very clean, it will be easier to keep clean. That is the main advantage of a bore scope. Most of us think that if we cleaned it, it must be clean. As you have shown, it can take a lot of work to clean up a barrel, even after we have cleaned it several times. I'm hoping you will find that Semichrome helps you remove the baked carbon much more quickly.

Different powders DO leave different amounts of residue and your bore scope will help you determine which ones are easiest on barrel maintenance. I've found that having a mirror smooth, lapped barrel really reduced the amount of fouling that any powder produces. I really don't worry about fouling too much in those rifles. However, the blowback carbon on ARs makes me real fussy about what powders I use.

I was surprised to read Semi Chrome has no particles in it, all chemical. I will see how it goes, just thinking, I might try mixing some J-B with the Chrome.
I read in the J-B instructions to run the coated patch in and out between 40 and 60 strokes. I do about 10 and put on a new coated patch.

[DakotaMan]

I use J-B for normal cleaning and it does a good job. I mainly use it for very dirty carboned up barrels like the Valkyrie barrel in my pictures above. It doesn't cut the carbon ring though. I suggest trying plain Semichrome first and mixing later as an experiment. I caution anyone mixing chemicals to be careful unless you are a Chemist because you could harm your bore with chemical reaction. As you say, Semichrome is simply a paste with no abrasives. J-B is paste and abrasive.

[jhjimbo]

Pulled out another rifle - thought it was clean.
This is Win '94

[jhjimbo]

I got the Semichrome today but need a replacement - the tub froze and popped the top off and spilled all over the package. At least I can get started.

Here is a after pic .30cal ranch rifle with 1 semi treatment.

[DakotaMan]

Much better Jimbo.