DaveMc wrote:Barry - to quote several (well respected and experienced) gunsmiths I have been talking to recently - "carbon fouling is the most common cause of loss of accuracy they are seeing lately"- whether it is different additives in the powder or some of the newer cleaning systems simply not working. There is also a trend to let barrels go for 200 rounds between cleans.
One gunsmith stated a 308 barrel was returned to him as a "dud" that was that bad that when he slugged it the slug measured 0.303 - now imagine that wobbling down the rest of the bore. After scrubbing and pasting it returned to full size.
I don't disagree with you on technique. Somehow I think the old bronze brush and Hoppes (tried and tested system) is better than many "modern day miracles" that only require nylon or patches. A pasting every few hundred rounds seems to work with this and gives proven long barrel life and effective results. After trialling most of these new carbon removers I also believe many of the other cleaners will work with the bronze brush (as you say - short scrub) as well.....just hard to get it out with a patch or nylon.
ps I also believe it is exagerated by "overbored cases". I originally faced a problem with the 6.5*284 and 2213 and a few guys up here with 243AI were seeing the same. The 7mm magnum seems worse than the 284 which in turn seems worse than the 308. I imagine the extra heat concentrated in the first few inches is the cause.
No doubt bore scopes come to play here and it appears as maybe more barrels are indeed being lost to overcleaning as much as carbon fouling causing accuracy issues.....???
To add to what DaveMc said and some others I will tell you what I see here.
One I don't believe in not cleaning at all. I say I shoot the gun I clean the gun. It's being pushed more and more over here by some tactical shooter/instructors to not clean the gun at all. I don't agree. Carbon build up will cause accuracy issues as well as pressure issues.
Not cleaning a .308win. type gun....as an example. This round is a very forgiving round but when you compare it to other calibers (especially over bore/over capacity type cases) the problem gets worse. Also differently types of powders will foul differently as has also been pointed out. Some powders just burn more dirty/carbon build up then other types of powders. Possibly even from lot to lot they can vary.
Just recently I had two different customers send in .30BR chambered barrels which have even less case capacity than a .308win. both customers complained that the barrels shot great when new but wouldn't shoot now. Barrels had a low round count as well and not even close to being shot out. Both barrels had a really heavy carbon build up in the bores and it was the only thing I could think of as causing the problem but I don't shoot a .30BR at all.
So first we cleaned the barrels some and then we gave the barrels a light relapping of the bores. First thing Jeff noticed here was how rough the bores felt when he first started relapping them. He said the first approx. 10 strokes the barrels felt like they hand sand in the bores and then they smoothed right. He finished them up and we cleaned them out and looked at them again and all of the carbon build up was out and they looked normal again and we returned them to the customers. Accuracy came right back and no complaints. I told the guys to keep up with the cleaning.
Also the ammunition test barrels we make for the military .300 win. mag. sniper ammo. Same scenario but concerning pressures. The military ammo is loaded very hot. Above normal working pressures. The ammo maker has found if they don't keep the barrels in check in regards to the carbon build up pressures will start to spike and go thru the roof.
I will say on one hand I see more damage from cleaning then from physically shooting the rifle but I do say you have to clean it. Just pay attention to how your doing it and don't do stupid stuff like not using a bore guide or even worse using a cordless drill to clean the carbon out of the throat etc...
Later, Frank
Bartlein Barrels
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