Copper and accuracy

[Elwood]

Right it's a given that copper fouling is a hinderence to accuracy, and for years I have been scrubbing barrels to get rid of copper.

 

So twenty years on, I'm now asking myself how does a copper build up effect the bullet and mess up the accuracy?

[1967spud]

at a guess i would say , can it build up to a point in the rifling to an extent to hinder the travel of the bullet in the lands

[auquhollie]

I found on my old 243 ack that when the copper built up so did the pressure, there for causing accurcy problems.

 

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[Andrew]

How did you detect the increase in pressure and tie to to the copper fouling? I have some rifles that have never had the fouling cleaned from them in half a century of use and they seem to function fine. Curious. ~Andrew

[Chris-NZ]

I guess I am still trying to wrap my mind around the term

"copper fouling".. my 1911 with 5,000+ ...will religiously cut the X from the the X ring.

 

So my question would be:

If I cant "copper foul" a barrel with 5,000+ rounds how is it

the ones that claim a problem do it in 1/10 the shooting?

 

308Panther

 

 

It's because it takes some high velocity on a decent barrel for copper to build up. Ever wondered why the copper is obvious down the muzzle end? The jacket material is obviously getting closer to molten as it exits the barrel.

 

I'd say the deleterious effect on accuracy come from stripping off variable amounts of jacket as the bullet passes, thereby destabilizing it.

 

Chris-NZ

[MarinePMI]

Interesting question...

 

Some say rifles shoot better clean than dirty. Some say no, their's shoots better fouled...

 

My hunch/thought is that its a happy medium. Copper, under pressure, becomes a lubricant (at least as I understand it). So I would say that some copper in the barrel may actually cause things to "settle down", by filling in the imperfections of the rifling process. Too much copper, and yes, I suppose pressures could rise, but I'd think they plateau at some point, as it would just get pushed out the barrel.

 

Powder fouling on the hand, I would think causes much more degradation of accuracy, as it is bulkier and thereby could cause enough of a blockage to cause pressures to rise, or bullets to not properly grip the rifling...

 

I don't think there's really any scientific way to prove or disprove this theory, but it is a theory I've often wondered about...

 

JMTCW...

[Guest Tiff]

I always like to keep my rifles clean. However my .308 Sako TRG will still shoot the same after 500 rounds in a weekend, as it does with only 5 down the bore.

 

Also when trying to burn out a factory .338 Sako TRG phosphate barrel, I fired 265 rounds through it in little more than 4 hours at Lydd!

 

The barrel barley got to touchable temperature the whole time! It certainly didn't get cleaned!

 

For the whole day the zero did NOT wander nor did the groups open up beyond 1 MOA at 1,200 yards! - (provided I did my bit with the winds).

 

After all of that use/abuse and 5,000+ rounds it still shoots 1/2 MOA cold bore shots!

 

For short range benchrest maybe copper does matter, but for me and my TRG's it seems to make little difference.

[Laurie]

It's because it takes some high velocity on a decent barrel for copper to build up. Ever wondered why the copper is obvious down the muzzle end? The jacket material is obviously getting closer to molten as it exits the barrel.

 

I'd say the deleterious effect on accuracy come from stripping off variable amounts of jacket as the bullet passes, thereby destabilizing it.

 

Chris-NZ

 

Absolutely true Chris. It's been long known that 3,000 fps is a critical MV. Virtually any gilding metal alloy bullet coppers the barrel more rapidly on or around that MV and above. Pistols rarely if ever copper because velocities / pressures simply don't reach critical levels.

 

Other alloys provide metallic fouling at different velocities / pressures. The original cupro-nickel jacket alloy was a demon fouler in early 20th Century military rifles at what we would now consider modest performance levels - eg early 0.303 Mk VII at 2,440 fps / c. 42,000 psi chamber pressure. The change to gilding metal (copper-zinc, in effect a low-zinc form of brass) reduced barrel fouling hugely - which was a GOOD THING as the military used such horrendous methods to get rid of it (mechanical methods as well as very strong chemical solutions) that they ruined no end of barrels prematurely in the process.

 

 

So my question would be:

If I cant "copper foul" a barrel with 5,000+ rounds how is it

the ones that claim a problem do it in 1/10 the shooting?

 

308Panther

 

Yes, but would you be able to say that after 5,000 rounds of firing roiunds loaded with a soft-lead alloy? I believe the traditional name for the .45 ACP 230gn RNFMJ bullet is 'hardball'. In my experience of the cartridge, this is an apt description of the standard .452" bullet. In the days when we could shoot such things here, I'd regularly find same on the sand backstop so little marked by either the rifling or impact with heavy wet sand that you were almost tempted to load them a second time. (In a similar vein, Terry Wieland recounts in his book 'Dangerous Game Rifles' that big solid bronze bullets have often been recovered unmarked from rhino and elephant and reloaded!)

 

 

My take on the effects of coppering is that it has all sorts of random, unpredictable effects on the bullet's travel down the barrel and how it subsequerntly behaves. In extreme cases it can act as a lubricant lowering pressures, but it usually has the effect that Chris mentions of any limited build-up damaging subsequent bullets and tearing small amounts of jacket material off. Where pressures and heat are extreme as in certain over-bore capacity rifle cartridges, it has been known to make bullet blow-up more likely.

 

My own extreme experience of coppering effects was my first ever 7.62mm Target Rifle, an ancient ex-club Enfield No.4 converted from .303 by Fultons of Bisley with one of those very hard / very tight-bore Enfield Lock heavy barrels. It was sold to me by the rifle club I was a member of and had performed about 20 years of sterling service with ordinary milspec 7.62 in its club-rifle role. The club 'keeper' had cleaned it after each outing with a bore solvent.

 

This rifle had a very odd trait. With a 'clean bore', the 1st shot would invariably be an outer at 12 o'clock, the 2nd a high-inner at the same position, and it would return to zero from shot 3 on. Nobody could explain this, until I read an article in the old 'Target Gun' magazine by Geoff Kolbe of Border Barrels about the need to de-copper with an appropriate solution. It took applications of Sweets every day for a full week to decopper the old Enfield! Then it shot to zero from shot 1. If I'd had a chronograph then, I'd probably have seen the first shot with very low MV (Enfields shoot high with low MVs because of the way the action / barrel flex), rising with the second, and reaching normal MV on the third.

 

On any account, any copper fouling is bad news accuracy-wise in most rifles. Speak to any BR shooter, and they'll tell you that allowing the slightest amount to remain in the barrel will increase group size. Normal practice for short-range BR shooters is to clean the barrel with something that also removes copper after 20-25 rounds.

 

Laurie

[Ronin]

Ian

 

 

see the recent 338 load post.

 

The groups shot (today) are through a barrel that has not been cleaned for 200 or so rounds, i'll take a pic of the muzzle / crown and post it if you like, the carbon build up is quite impressive

 

 

Shoot it untill it askes to be cleaned is my perspective on things (at the moment)

 

 

I do think it is down to individual barrels how frequently they require attention.

[DL.]

Ian

 

 

see the recent 338 load post.

 

The groups shot (today) are through a barrel that has not been cleaned for 200 or so rounds, i'll take a pic of the muzzle / crown and post it if you like, the carbon build up is quite impressive

 

 

Shoot it untill it askes to be cleaned is my perspective on things (at the moment)

 

 

I do think it is down to individual barrels how frequently they require attention.

 

Will rust not form in the rifling if the barrel is not cleaned and oiled before it is put away?

[shrek]

My 6BR is very accurate normally, however when it has had 70 to 100 rounds through it without cleaing it is supremly accurate, however as its often long periods of time between uses i tend to borefoam the barrle just so its sitting clean.

 

clean or fouled, the rifle is probably more accurate than i am, so i just shoot it!! im not a precision target shooter, however i know the rifle can shoot better groups than i can so im in a happy medium

 

DL. Have i convinced you into gettin a 6BR built yet?

[DL.]

Something about leaving a rifle in the safe with a fouled barrel doesn't feel right, I do when I am going to be using it again the same week, but otherwise, pull it through 'till it's clean and leave it oiled up.

With the copper solvent, I don't shoot thousands of rounds, so have only used it a couple of times, and couldn't say I noticed a difference with all the other variables that seem to happen with results on paper.

 

Shrek, I think 6BR fits the bill nicely for a Roe/Fox round at greater distances than the .223 would produce the goods.

Still, getting another rifle would be a great excuse to start load development all over again

[Ronin]

DL

 

I understand your concerns, if it were wet, I would have at least had an oiled patch through the barrel.

 

My cleaning regime pretty much depends on what rifle I am shooting.

 

Some get used alot, my 6.5x47 and 338 come into this category, they are target guns but surprisingly do not require a great deal of TLC to keep shooting accurately, the 6.5x47 for example has had at the last count 3000 rounds through it, (I buy my 123 scenars in 1k lots) so its easy to keep a check on what ive used (besides having - I am on the 4th box in maybe three years.

 

Last month I shot it in a BDS comp, I shot a .2" group off a bipod on the zero card (30 ex 30) and scored 119 ex 120 on the roe target seated, kneeling and standing.

 

It has not been cleaned properly since I shot at Warcop in July (I think) and I use it pretty much each week....

 

The same applies to the 338 although this has shot fewer rounds.

 

Conversly, if I left my 7mm /270WSM without cleaing more than 100 rounds accuracy deteriorates below what I consider acceptable, so it get cleaned after each comp or practice with great care.

 

 

My stalking rifles.

 

I have a few, they do get exposed to real sxxtty conditions and are cleaned, stripped and oiled after each outing reagrdless of being fired or not.

 

 

i don't like the idea of moisture in the barrel, but carbon and copper tend not to bother me much, untill accuracy is affected.

 

 

Ive said before and will repeat, the rifle will tell you when it needs cleaning (of copper / carbon), too much cleaning can have a detrimental affect on barrel life - especially if done wrong (no bore guide, not unscrewing the jag before retracting the rod etc)

 

 

All barrels behave differently, some need cleaning often, come not at all.

 

 

Like all things in life, everyone is unique