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Discussion Starter #1
I purchased a beretta 682 barrel with mobile choke that has been backbored to .740 it only came with one (.022 constriction ) choke tube who would you use to make a couple for it? Thx Jerry
 

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i started shooting comp n chokes-- man do they smoke rocks and pattern very well--
generally on backbore barrels- it makes chokes one size tighter
 

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Jerry, if you deal with Briley, speak with their choke tube guru and specify that you have a specific bore size and want Mobil type choke tubes to fit that barrel/bore size.

Pat
 

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Pat[/QUOTE]
Jerry, if you deal with Briley, speak with their choke tube guru and specify that you have a specific bore size and want Mobil type choke tubes to fit that barrel/bore size.

Pat
Who is the choke tube guru at Briley? Lester
 

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Jerry.
The first thing that I would do is to check your barrels with a bore gauge to give you the exact internal diameter bore sizes along the whole of the ID of your barrels. It is usual that the back boring of barrels do not extend into the "ORIGINAL" choke tube section of the barrels. Is the only choke tube that you have "a original unmolested Beretta choke tube" with only the mouth of the choke tubes tapered entrance diameter being enlarged to be slightly larger than the back bored barrels diameters. You might not need "completely new custom choke tubes" if you only need "choke tube mouth entrance work undertaken" on standard original sized replacement tubes. Have a diagram drawn of your barrels inside diameters from forcing cones up to a "few thou" before the choke tubes mouth seating faces
I will measure the mouth of a new original mobil choke tube and get back to you. It is precision work but not rocket science.
Thanks
Phil
 

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Try and see if a Mobil choke will screw into your barrel. Then run a rod (a new pencil or a small blade screwdriver) down the edge of the inside of the barrel, to see of the ID of the installed choke is a larger diameter than the barrel. You should be able to feel the ridge in the barrel, and can also see it with a flashlight. If that is the case, then the overbore tapered back to the original bore before it got to the threads, and you should be able to use normal Mobil chokes. That ridge will keep the wads from catching on the choke tube. You just have to do the math, to see what the total constrictions are with the chokes you install. They will be tighter than what is marked on the choke.
 

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Jerry
There are some details on the internet stating that some of the Beretta 682 models e.g. "the competition modes" were available from the factory with the larger back bored barrel sizes ???
Your new starting point is that "you need to be sure" that you either have "factory over bored barrels" or "aftermarket gunsmith over bored barrels" You need to know that first ?
(standard bored Beretta 682 factory barrels measured 0.722 to 0.724) with the "completion barrels" being up to 10 to 18 thousandths larger.
Thanks
Phil
 

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There are some details on the internet stating that some of the Beretta 682 models e.g. "the competition modes" were available from the factory with the larger back bored barrel sizes ???
Your new starting point is that "you need to be sure" that you either have "factory over bored barrels" or "aftermarket gunsmith over bored barrels" You need to know that first ?
(standard bored Beretta 682 factory barrels measured 0.722 to 0.724) with the "completion barrels" being up to 10 to 18 thousandths larger.
I competed with 682 Sporting,which is considered a "competition model" which was fitted with custom tubes from Kolar. This gun has Mobile Choke barrels with a bore of .723.

This is the first time I have ever heard of "factory over bored barrels" being available for 682 models. Is this just internet talk" (as I suspect), or is this FACTUAL. If so, it would be great if you could provide information as to official Beretta documentation to this.

Yes, there are gun shops that will over bore barrels, but I am not aware of Beretta providing such a service.
 

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Discussion Starter #12
The barrel has a money maker rib on it and I assume they did the backboring.the barrel mics at .740 and the entrance to the choke tube is .738 and is a factory mobile tube marked IC the constriction end is .718 it's the only tube that came with the barrel,it surprisingly breaks 27 yard target well Jerry
 

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Measured a new in the box Extra Full Mobil choke tube for your information Jerry.
Diameter of the OD of the skirt of choke tube is 19.80mm which is 0.7795276 inches.
Choke tube skirt wall thickness is a gnat's whisker over 0.50mm which measured 0.02047244 inches.
Diameter of the ID of the mouth of the choke tube is 18.70mm which is 0.7362205 inches.
You "PROBABLY" have a "Factory Mobil Choke Tube" that has had it's choke tube mouth enlarged so that it would have "SUFICIENT" tolerance to match your 0.740 inch bores ??????? Check and then "TREBLE CHECK"
ID diameter of the muzzle exit of the Extra Full choke tube that I have/measured is 17.35mm or 0.68307087 inches which could give as much as 0.036 thou of choke from a standard 0.724 inch bored barrel.
Relative easy job to sort out as long as you can measure accurately etc. ???
Good luck and read my above posts with this post.
Phil
 

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If the bore diameter at the start of the choke tube recess is .738 and the inner diameter of the choke tube mouth is .775 wouldn't a standard mobil choke tube work? However I cannot make your dimensions work. If the choke tube skirt o.d. is .779 and wall thickness is .02 how can i.d. be .775? Not arguing, just trying to understand. I work with a mobil choke barrel overbored to .738, but it was left at .725 just before the start of the threads, so mobil chokes work ok, but of course shoot tighter patterns than would be expected from a stock barrel.
 

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Jerry only a bore gauge is going to tell you the exact bore measurements from the back of the forcing cone diameters through to just before the start of the choke tube seating faces, it is a common practise for back boring to only run from the back of the forcing cones to near to the choke tube seating faces "NOT EXACTLEY UP TO THE CHOKE TUBE SEATING FACES" because it is a far more expensive job to alter original choke tube machining dimensions. Yes you can alter choke tube ID dimensions as long as you have enough "meat on the bone" that the OD of the choke tube will allow you to machine off the ID of the choke tubes etc. ???
"A BORE GAUGE WILL ANSWER A THOUSAND QUESTIONS" Picture the back bored section of the barrels as a extended taper running from the back of the forcing cones running to no enlargement of the bores just short of the choke tube seating faces e.g. similar to "A EXTRA LONG GRADUAL TAPER"
Phil
 

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My scribbling's are unreadable to me, need better glasses. Sorry.

19.80mm or 0.7795276"
18.70mm or 0.7362205"
-------------------------------
1.10mm or 0.0433071" divide by 2
0.55mm or 0.02165355"
-------------------------------

Phil
 

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My scribbling's are unreadable to me, need better glasses. Sorry.
19.80mm or 0.7795276"
18.70mm or 0.7362205"
1.10mm or 0.0433071"

Phil
Use the significant digit rule and avoid confusing yourself.
 

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Thanks Flashmax.
She who must be obeyed has stolen my Vernier gauge batteries for an "EMERGANCY ???" with one of the grandchilderns games ??? and I am reduced a DTI gauge, nothing is safe, and I dare not moan as I am not in her good books anyway :anim_rofl2:
Phil
 

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Discussion Starter #19
Phil,I did use a bore gauge on the barrel the maximum bore dia. is .740 it tapers to .738 where the choke tube seats,I'm a mechanic so "mics" is just the term in my brain that refers to fine measurements...LOL .Jerry
 

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If your bore ID at the choke tube cut is .738, and the ID of a factory Mobil choke is .736 at the receiver end, then you can't use factory choke tubes in your gun. The wad will catch on the ridge, and cause major problems, IMO. I would call Briley and see what they suggest.
 
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