CHROME LINED BARRELS

[James Storm]

Why is chrome lining of barrels not used more, especially in high power shooting?

[Tim S]

I'd say simply, because it's not necessary on a civilian target rifle. Chrome-lining is common for military rifles to prevent corrosion, whether due to the chemical composition of the ammo (chlorate primers) or environmental conditions. These aren't factors for the civvy market. Modern 0.22LR ammo isn't corrosive, rifles are used in sheltered ranges, and shooters can clean easily. Accuracy is more important than minimal maintenance.

For CF shooting much the same is true, although ranges may be less sheltered. I have heard anecdotally that when lined barrels go (due to the inevitable thermal damage from 45,000+PSI pressure) the deterioration in accuracy is quicker and more severe than with an unlined barrel.

[James Storm]

I often hear numbers like 900 to 1500 rounds for gilt-edged accuracy from a top grade center fire bench rest barrel. I would think that chrome plating the barrel would extend the gilt edged window. I wondered if plating degrades accuracy. Jim

[James Storm]

I often read about numbers like 900 to 1500 rounds as the limit for gilt edged accuracy from a top grade bench rest barrel. I thought that chrome plating might extend this period of gilt edged accuracy. I wondered if in practice the chrome plating tended to degrade accuracy instead and if this were the case, by what mechanism? Jim

[NMC_EXP]

When the M14 rifle was used by the US Army and USMC rifle teams: (1) Standard issue barrels were chrome lined. (2) Special National Match barrels were made by the same suppliers and these were not chrome lined. These barrels were used for the accurized M14 rifles. Toward the end of the M14 the military teams used commercial match grade barrels as well.

I have not seen any data regarding either barrel life or precision on target regarding with vs w/o chrome lining. I'd assume there was no advantage or a disadvantage to the chrome otherwise the military teams would have used it. These teams did a lot of R&D to get the most precision out of their rifles.

It seems to me that plating the ID of a tube and maintaining tight, consistent tolerances would be a challenge and another source of variability.

[Tim S]

I often hear numbers like 900 to 1500 rounds for gilt-edged accuracy from a top grade center fire bench rest barrel. I would think that chrome plating the barrel would extend the gilt edged window. I wondered if plating degrades accuracy. Jim

James,

BR shooters buy premium grade barrels from small boutique makers. It's unlikely that these shops have the capacity to chrome plate a barrel, and will chrome plating affect accuracy? The major military contractors won't want to bother with small runs with obscure twist rates that require special mandrels.

I think 100-200 yard group shooting barrels have such a short competition lifespan is 1) accuracy, and B) pressure. The 6mm PPC that dominates is very high pressure, about 60,000psi.

[James Storm]

Do you think that chrome plating, if available, would reduce the erosion in the barrels used with these high pressure rounds?

[Tim S]

Perhaps, but you'd have to find someone willing to try, and someone willing to make one to BR spec. Would the chrome need to cover the chamber too? From what I know few serious BR shooters would accept a pre-chambered barrel, so it's possibly moot. You might get a better response on a BR specific firearm.

Perhaps meloniting would be more successful. This appears to treat the metal, rather than plate it. However for 50m 0.22LR shooting, comparatively few shooters will put enough "mileage" on a barrel that the cost of any treatment to extend the accurate life is justified.

[bill guinn]

Go to any center fire match, be it benchrest, F-class, 300 meter etc. and count the number of barrels that are NOT stainless steel. Guess what makes stainless steel not stain.

Better to put the chrome in the steel than on it.

[marky-d]

I suspect that this common observation is more related to trends and availability than data-supported decisions related to accuracy or durability. Plus it used to be that a stainless barrel (of similar quality) was typically cheaper than carbon steel + bluing. That may no longer be the case with the protective finishes available today.

I think it's similar to the whole hammer-forged versus button-rifled debate. Walk down any competition line and count how many hammer forged barrels you see. Some interpret that to mean button rifled barrels are inherently more accurate, etc., etc. But from what I've read, there is no such cause-and-effect relationship. Really, all the 'best' barrels come from relatively small manufacturers. Hammer forging machines are very expensive and only make sense if you're making huge quantities, so the low-volume manufacturers use other technology. Both methods CAN produce accurate, long-lasting barrels, but economic factors push them to different consumer markets.

marky-d

[Tim S]

I think it's similar to the whole hammer-forged versus button-rifled debate... Both methods CAN produce accurate, long-lasting barrels.

marky-d

Mark,

Soviet made rifles, like the Ural 5, were built with hammered barrels, and were certainly competitive during the '80s; the first 600 on the 1989 targetswas shot with a Ural. It would be interesting to see how one of these would perform with a decimal score, possibly from one of the modern more rigid actions.

[marky-d]

Yeah, the CM-2 I bought for my son is hammer-forged too. I can't verify how accurate it actually is -- probably not comparable to a 'real' precision rifle -- but it is definitely more accurate than him or me!

marky-d