Home Forums Hunting & Shooting Gunsmithing Advice sought on dark bore

I recently bought a Zastava 8x57 takeoff barrel on Ebay (yeah). The barrel is just perfect for use in replacing an 8mm-06 on one of my Mauser sporters...contour, weight, beautiful blueing...but when I got it and started cleaning it I discovered it is dark, frosted black bore. The seller didn't know, hadn't cleaned it, and he gave me a full refund instantly and told me to keep the bbl.
I'm starting to wonder if maybe I should put some effort into polishing the bore, I suspect that someone got their hands on some cheap corrosive 8x57 ammo, and not knowing better, didn't clean it after some fun blasting. The lands and grooves are well defined, and what I can see of the throat looks good.
I was wondering if any of you guys had tried to polish a neglected bore...what method? was it worth the labor? results on target?

I wrap a loose-fitting patch around a Parker-Hale jag, then add some superfine steel wool. I then charge this with some 400 grit lapping compound and go to work. 50 to 100 strokes should do it. I set the barrel up to keep the jag from coming out the muzzle. You will feel when the barrel smooths out. A somewhat better result can be had with a lead lap. Polishing with a resilient backing will perpetuate tight or loose spots while, with a lap, you can smooth them out. GD

Flintlock a few years back I had a zastava in 8x57 same problem. I read that they were imported as used sporters and apparently they all had poor bore condition from corrosive ammo and no barrel cleaning. No fix to it never got mine to clean up just get rid of it.mb

Greydog, I have 4 grades of Clover compound, some micro flaked sapphire compound (Dave Corbin's secret sauce for lapping bullet swages)...so the question is, for the lazyman, I wonder if fire lapping would slick things enough to avoid excess coppering? I could have a stroke at the thought of stroking a hundred passes. Snork.

OP,
A wet patch w/ bore solvent.
Silicon carbide oil base lapping compound of 120 grit on a patch & jag for 1/2 a dozen full passes.
A wet patch w/ bore solvent.
The above w/ 240grit.
A wet patch w/ bore solvent.
The above w/ 320grit.
A wet patch w/ bore solvent.
A dry patch.

Insert bore scope for verification.

Time invested....less than 20minutes.
Done

friend of mine has an Arisaka with a dark bore and it shoots incredibly well

Dark and/or pitted can still shoot good.

I'd start with Wipe Out.

I’d start with a bronze brush with 0000 steel wool with some oil on it before I begin anything aggressive. If it’s grooves are well defined and the throat looks good it might be fine as is. You remove something you don’t want removed.

Shoot about 100 paper patched bullets and it will shine right up

I'll repeat the advice to shoot it before passing judgement. I've had "dark" bores that lived up to their name accuracy-wise and for whom no amount of coaxing proved otherwise. I became an evangelist for denouncing dark bores as a reason to avoid rifles. Then six months ago I was gifted a nice solid Remington #5 M1905 Rolling Block 7mm whose bore was, naturally, quite dark but with sharply pronounced lands. Not being a complete idiot I accepted the gift and said "thank you very much."

Turns out it shoots quite nicely. No plans to change a thing with it:



That's five shots at 50 yards, issue sights, low vel jacketed bullets, a Lyman manual starting load.

Holy touching holes! I have scoped deer rifles that struggle to do that..you did that with irons at 50 yds. Feel free to share powder and bullet weight, LOL.
Back to bore appearance...I think you have convinced me to test that 8x57 barrel, it's been wave after wave of snow, wind, rain so I haven't defiled that bbl yet with abrasives.

Back to the 1905 roller....have you run into any anomalies with the chamber being a little different than SAAMI or CIP specs? I have a 1901 (maybe, hard to identify) around here someplace. Never really examined it, bought for the action, but I recall it had a dark but shootable bore. I recall reading something by John Taylor over at Cast Boolits, that there were a lot of 7mm rollers with chamber variations...ring a bell with you?

Yes, the one I had the issues you mention. Never could get it to shoot very well. It's now a 38-55.

https://www.thehighroad.org/index.php?threads/loading-for-the-7x57mm-rolling-block-rifle.829871/

Yeah #5 Roller 7mm chambers are all over the map. Some are pretty egregiously long as a matter of fact, and a lot of theories as to why. (Utter functionality in 3rd world sh*tholes whose illiterate troops were wont to cram any old crusty corroded ammo into their guns is a favorite one.) I was aware of this anomaly so I did a chamber cast before I did anything and sure enough the headspace was .030"+ longer than SAAMI specs. (And no, my action isn't worn such as to have developed sloppy headspace. The breech block and hammer pins are perfect with zero play. I doubt the rifle was fired much as opposed to neglected a lot.) To overcome it I used two approaches: 7x57 brass necked up to 8mm and then incrementally pushed into the 7mm die until the breechblock would just baaaaarely close on it. The second approach was to simply start with 8x57 brass and do the same trick. That little secondary shoulder is enough to keep the case head back against the breech face for the initial firing. After that it was neck size only. I suppose if I shoot it enough I might have to bump a shoulder back at some point but my loads are pretty mild and I shoot it so seldomly that it may well be a moot point.

I'm not home so I can't consult my records as to exact load but it was with 4759 powder, either 16 or 18 grains, and a no-name 139 grain jacketed seated way out. (Sometimes it pays to hoard bullets that you don't know who made them or have a rifle to shoot them in!) Next up I wanna try a 175 round nose a la original early military ammo. I acquired a 140 grain gas check bullet mold so I guess I have to try it sometime. Thankfully it casts a bullet sufficiently big to fill the throat, and cast hard it just might work (at least until the dark bore sandpapers enough lead off of the bullets to lead things up and cause accuracy decline).

Hah! I went and read that link and evidently like minds think alike!

One thing I'll strongly suggest to anybody with a Roller whose trigger pull is a fairly typical 6-10 pounds: get a replacement trigger spring made of music wire from rollingblockparts.com. They're only a couple bucks, easily fitted, and reduce trigger pulls to an honest 3 pounds or a bit less. Be aware though if you call the proprietor, Kenn Womack, he's a really nice guy who likes to chat and the call might last a while!

When I got mine I realized how utterly simple they are and said "cripes, give me some correct diameter piano wire and I'll finagle my own. But then I reflected on the cost of a roll of wire and the time to do it.....