Getting a well-used tool accurate again

[Wapiti]

I thought this might be of use to you guys who love to use well-used or older stuff,
maybe old military firearms with really dirty barrels that just have carbon'ed up to hell.

My well used 7600 pump 308 has been around since I had to sell my M14 and L1A1 off to a well-known theft of many of our useful firearms.
It's fired 1000's or rounds, mainly in the bush and it's been out in pouring rain, gummed with dust mixed q\with oil, lent to knew shooters keen to try it, everything, for 30 years. The first original pump forend was ripped off after being chewed off by getting in a tractor loader mechanism (don't ask), it was lost from a ute and cartwheeled down the track, ripping the 6-48 screws out of the action that hold the mount on.
I got another forend online secondhand, but it now wears a Lucky13 adaptor to fit a Magpul 870 forend the same colour as the rear stock that I fitted because it has extra heights for the cheekpiece to get my eye in line exactly with the scope for lightning fast on-target aim.
It still wears that 3-9x VX2 scope, which hasn't missed a beat even though it's been hammered.

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It used to easily shoot MOA with 45gns 2208 and 150gn Taipan bullets (remember how absolutely perfect they were from 2600-3000fps on huge pigs?)
in the old days.
But lately it's been terrible, shooting 3" or worse for three shots. I tried everything, clean, clean, clean with different bore chemicals, scope mounts, barrel float clearance (these things have full-floating barrels), tightness of barrel in the action, everything.


So I tried this... the chemical paste that made the awfully finnicky Howa 243 stainless I made the mistake of buying, actually consistent.

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So, on a jag with a tight patch coated in this stuff, maybe 20 strokes back and forth.
Then another one, about 20-25 times.
Both came out black as coal as could be expected. This was from a barrel cleaned with copper solvent first, until no green came out at all.
then a super-clean with good 'ol Hoppes 9, until patches and chamber were clean.
A look with a Teslong borescope I bought showed a chrome-like mirror finish, with rifling lands still sharp and crisp after all this time and use. Unbelievable.

Well, first 3 shots was under 25mm at 110m, so another 3 over the top of those once it had cooled. Group didn't get bigger.
Then I tried some 150gn hollow-point Sierra "Varminter" flat-base projectiles, 3 shots over the top exactly.
The old girl is back!

Don't underestimate the poor results a huge amount of use allows this bastard carbon to gunk up the rifling in front of the chamber and wreck the consistency and the accuracy.
This awesome stuff is available even smaller towns like ours, at Autobarn, Repco and SuperCheap. Do not think you need to buy special "bore paste" at huge prices, or never be able to get any.
Just a heads-up here.

[tuknal]

interesting
i have howa 223 that can be a bit the same with about 1500/2000 through it/and a sako thats starting to open up too ,im assuming the barrels on its way out cos i bought it 2nd hand not knowing how much its done ,even though i was told itd done not much and is in excellent condition ,a barrels ordered and coming for it ,
so do you think this polish got rid of fouling the hoppes and copper solvent couldnt
ive seen that polish around might have to give it a go before i rebarrel just for interest sake
do you recon a nylon brush coated in it would do the trick ,ive only got an eyelet type jag but i guess thatd work too

[Wapiti]

I can only assume that all the carbon in front of the chamber was upsetting things, because nothing else had changed.
Over the last few years it got worse, I even changed the scope, to a newer one but that did nothing either.
I'd read about this stuff called Bore Paste that the yanks always go on about, which I could not find. So a bit of looking around showed it was just metal polish. So I tried some Autosol from Repco in town, and that took out all that black carbon crap and now the bore is really shiny and the accuracy came instantly back.

I have this stainless Howa 243 that's always been really bitchy about what it will shoot, just wouldn't group with anything basically. It has a few issues. quality control ones, worst one was a really short chamber, would only easily chamber cases that had been over-full length sized and shortened, the first 20 or so shots from new badly galled the locking lugs from trying to close the bolt on 3 different brands of factory loads.
Anyway I used this stuff also to slick up the locking lugs and polished the hell out of the barrel with this metal polish and that made a huge difference.
It's still a disappointment with a short chamber, but it's way better at keeping groups good enough now.

Anyway, maybe it's a coincidence.
I use a spear jag, a pointed one, with a patch that is tight when in the bore. I just rub the paste into the cotton patch on one side, insert it and give it about 20 strokes each way, ditch the patch then use another impregnated one. do it a few times.
A first when it's taking off the carbon, it will be jet black and filthy, like graphite grease. after a few goes that stops, when the crap is all out the patches still are black but way less so, because it's polishing after all, but you'll see what I mean.
If you can, use a bore guide to prevent the white paste from getting in the action and causing you extra clean-up.
With the pump I had to do it from the muzzle but used the brass centering cone that came with the rod to keep it from rubbing on one side of the bore, and I also used a carbon-fibre cleaning rod which just doesn't bend.

It's worked for me a few times, so i just put this up as it might help others with similar issues.

[Fester]

Yeah, I think a snug patch on a jag is best for the JB bore paste or other metal polishes, as other methods may not polish so well.
On bikes, I used a tube of Autosol for a coarse-roughing polish, then the Mguires fine stuff to finish.
With metal polishing, the cloth always goes black even without carbon.

Carbon sure seems to be the enimy the barrels and the chamber carbon ring area.
After getting a Teslon scope, it became more obvious how hard carbon is to remove if left to build up.
I think the only real way is to polish it out.

I am a fan of maintenance cleaning to try and not let it start, and still thinking of adding the JB polish about yearly.
My borescope now still shows a black ring mark, but not an actual ring buildup, I think only a good polish will see if that mark can come back to a shiny metal finish.
I just haven't found the time to be assed doing it yet, and maintenance cleaning is keeping them shooting fine.

The borescope also showed how thorough we must clean out polish residue.

[ButchDDG41]

I used to get roped into polishing all my dads mates harley's with autosol when I was a young fella. I bought a tube the other day to revive the chrome on my ZD fairlane I recently picked up. Works a treat. What also works awesome but probably has no relevance here is a hunk of aluminium foil with water, polishes up old spotty chrome well, and if you combine autosol and foil its great as well.

[Wapiti]

I used to get roped into polishing all my dads mates harley's with autosol when I was a young fella. I bought a tube the other day to revive the chrome on my ZD fairlane I recently picked up. Works a treat. What also works awesome but probably has no relevance here is a hunk of aluminium foil with water, polishes up old spotty chrome well, and if you combine autosol and foil its great as well.

Ahh, does the alum foil rub a bit of silver colour into the rust spots?