doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Opening chokes on chrome lined barrrels

pretty sure this has been asked before but does the board know of a good 'smith that can open chrome lined barrels?

I have heard this gentleman does good work, and I believe he also works on Chrome bores. I have no personal experience with him.

Mike Orlen, 79 Salem Street, Amherst, MA 01002

Phone: (413) 256-1630 Fax: (413) 253-5665

michael.orlen@verizon.net

The whole chrome choke "problem" is so much bovine waste. The chrome is only a couple molecules thick and the tungsten cutters that any respectable smith uses goes through that like butter. But the myth is always good for a sweet additional fee.
Have a day
Dr. WtS

Skeet's Gunshop, Tahlequah, OK. Dean Harris, best there is.
JR

You will be wise to follow advice of John Roberts on this issue.

Other than being pleasantly surprised by the excellent condition of the bores when I cleaned them of 2 well used 12 bore over and unders (a Valmet and an SKB - both I assume made with chromed bores) I have little experience of the benefits of the process.

Do members find that factory chromed bores offer a real protection, particularly in humid and/or salty conditions?

If so, given that opening the chokes must lose that protection for at least an inch or more at the muzzle, would it not be better to try spreader loads instead?

I’ve seen chrome lined barrels have the chrome stripped out of them like a potato peel by inexperienced gun modifiers.
Seldom does anybody attempt to polish the surface finish in the choke area that was modified to match the mirror like finish the chrome provided prior to removal.

Time is money, so if you want a nearly invisible choke reaming, you have to pay for it.

Dr Wonko is inaccurate on this matter.

FWIW, chrome is hard, it takes a piloted reamer w/ carbide cutters to cut it precisely. Is it always best to make sure the gun modifier has the right tools before you hand over your barrels. Or disappointment will follow.

I was told by Orlen that chrome lined bores will not peel off, regardless whether you ream the chokes or not. He said that the chroming process is totally unlike a chrome car part, such as a bumper, which it is plated over another alloy. He said that the process used in barrels alloys the chrome with the steel bore, and it can never peel off. It is not plating, said he.

Just saying what I was told.

Chrome lined rifle, machine gun, and shotgun barrels have bores that are indeed chrome plated. The process electroplates a very thin plating of chrome on the inside surface that is done for wear resistance, and in the case of rifles, inhibits erosion from hot powder gasses during rapid firing. The very smooth surface also makes cleaning and maintenance easier.

The process for the bores of firearm barrels is specialized, and much different from the process that was used for decades to chrome plate bumpers and automotive trim. That was a multi-step process that involved an extremely thin electroplating of copper, followed by a much thicker layer of nickel, and then followed by a very thin layer of chrome. When this process was not done perfectly, sometimes the chrome would begin to delaminate, flake, and peel off. The exterior of some handguns were also plated this way, and we often see older ones that have the chrome flaking off.

https://faxonfirearms.com/blog/frequenty-asked-questions-nitride-vs-chrome-lined/

The chrome is not alloyed into the barrel steel. It is only deposited onto a surface that has been etched and prepared to ensure very good adhesion with the steel. However, there are alloys such as 4140 Chrome-Moly steel that contain roughly 0.1% chromium, along with molybdenum, and manganese that provide more toughness, corrosion, and abrasion resistance than the earlier low carbon barrel steels found in our vintage guns. Opening the chokes on a Chrome-Moly barrel will not remove the chrome. It is indeed alloyed into the steel.

Many gunsmiths charge more to open chokes of chrome lined barrels simply because tooling such as the carbide reamers or cutters mentioned by Dr. Wanker are not used by most gunsmiths that do a lot of this work. Instead, they prefer to use something like a rigid Sunnen sizing hone. Also, the chrome plating, although very thin, is much more than "a couple molecules thick". And it simply takes a bit longer to properly get through the harder surface deposit of the chrome than it would to open the chokes by an equivalent amount on a vintage shotgun barrel with mild steel barrels. Time is money, and most gunsmiths charge for their time. Some may charge more, or even refuse to do the job, based upon myths and misconceptions about the job. When the surface layer is removed from your chrome lined chokes, the new polished surface in that area will be whatever alloy of steel the barrel was made from. Since the chrome lining is seldom much over .0015" thick, opening the chokes is going to completely remove it in that area. It is unlikely to be very evident if done correctly. But over time, the bare steel could begin to oxidize or show the effects of corrosion while the rest of the bore maintains its' chrome plated surface.

Absolutely correct. It's also called chrome hardening and has a multitude of industrial applications

Have a day
Dr. WtS