doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com How Thick is the Chrome on Beretta 686 O/U Bores?

Gunsmith Question -- I want to open the chokes on a Beretta O/U (686). They have chrome bores, right? Can I cut this chrome in a controlled way with a regular HSS adjustable reamer(piloted for concentricity?), or do I have to grind through it first with a hone,and then ream to final dimension in which case I worry about concentricity of resulting choke with bore. Anybody know how thick this chrome is, by the way, and when it is put on? My guess is bores are chromed after the choke, chamber and forcing cone are finalized. Is the chrome just a flash coat, or something thin and fairly uniform in thickness?

Thanks for any help you can provide.

You need carbide reamers to open chrome lined bores. You will ruin HHS reamer blades. I have never tried honing off the chrome but I think it would be tough.

I do lots of choke work but when I get one with Chrome I send it to Mike Orlen. He has the right tools for the job.

Mark

http://www.mbabllc.com

I'm not sure that all (or any) 686's have chrome bores. I have three early 686 Onyx guns (with the black frame, steel grip cap, and Mobil Chokes) and I'm pretty sure that none of these have chrome bores. I also don't think I've ever seen a U.S.-spec 686 with fixed chokes that would need opening. I believe there were Euro-spec guns (S56E?) with fixed chokes. These look like 686's, as I recall. The BL-series guns also had fixed chokes, as I recall.

Yes, the barrels on the Beretta 686s and 687s are chrome plated to prevent corrosion from steel shot. Good luck.

I think you will find that all 680 series guns have chromed bores.

Steel shot was not the reason, as the design predates steel shot and early Mobil-Choke guns were not suitable for steel shot - that fact I know for sure.

It's easy to find out. Just use some cold blue in the choke area. Cold blue will not color chrome.

Thanks for the replies. The bores in question are chromed, are on a 686S, are fixed choke, and are 24 gauge, F and IM, of all things. I had spoken with Mike Orlen quite a while ago on this. He wouldn't do it, and I don't blame him a bit, as it really is an oddball job. He didn't have the right sized carbide reamer, uncommon gauge and all, and I think he only uses bushing guided reamers, which is the right way. He stated carbide or grinding was the only way through the chrome, and wasn't confident any hone grinding would stay concentric. I can definitely see how it probably wasn't going to be a profitable exercise for him.

In asking my question above, I was thinking about taking my chances with the chrome by grinding through with a hone, and wondered if anyone out there really knew how thick or uniform the chrome plating is. Other alternatives are to either have a custom reamer made, or make some carbide blades to fit an adjustable reamer -- no small task, and probably over my head. Failing that, there are always spreader loads, I guess.

MS,
The thickness of the chrome will be very thin. How thin would be a guess. I'd guess less than a few tenth's of a thousandths. The problem with honing is that as the hone cuts thru the plating, it will almost undoubtedly cut thru one are first. This will then allow faster cutting in the steel and cause a shift in the cutting concentricity. How much? I dunno. Maybe not significant, maybe really significant.

MS, Charlie Boswell at 912-829-3936 regularly reams chokes in chrome lined bores. I doubt very seriously if he has a reamer for 24 gauge but all it would take would be a phone call to see. He has done several for me in 12 gauges, and I have gotten perfect results on the pattern plate every time.

Yup, you got the picture Chuck H. That's what I'm worried about, Once you've ground thru the hard stuff in one place, the soft stuff wears at the highest rate. That's why guided reamers are preferable.

Stan, thanks for the contact for Mr. Boswell.

Not to start an argument, but, I had to check this out to be sure-Beretta Worldwide Catalog, page eight -the page with the 687 Silver Pigeon Field Grade- "Internal chrome plating offers maximum protection against corrosion and resistance to barrel stress caused by the firing of cartridges with steel pellets."