doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com reaming fixed chokes

Thanks for the thread, it's very informative and sorta makes you want to try it yourself (starting? of course, with a gun you might just as well throw away).

I've got a question concerning chrome-lined barrels - can you open them, too? I've been told that if you damage the lining, the corrosion is going to get under the lining, where you can't possibly clean it out, and is going to ruin the barrel - is there any truth in that?

Jim;
As I understand your post you were providing a positive means of assuring the reamer aligned with the bore. I presume you do understand I was not speaking of this, but my caveat referred to simply reaming with an unguided reamer, depending upon it to "Allign Itself". If only very light cuts are taken it will generally do a pretty good job of this when there is a parallel section to guide. In the case of the taper choke there is of course nothing to serve as a guide.
Statements made in Lefever catalogs actually said their chokes extended from "Breech to Muzzle". I suspect this was simply a poor choice of wording on the part of the writers, but many writers, without "Finding out for Themselves" have repeated over the years they were choked for the full length of their bbls. I have never seen one so made or have any knowledge of anyone else who has.

Alot of good information here. Thanks folks. The wheels are in motion and I've ordered the adj reamer and a D reamer + blades and a long handle. I'm a little vague on 'parallel surface' so if one of you could further explain I'd appreciate it. I like that idea of modifying a snap cap to use as a guide. I have the rest of the tools. I have a small lathe to create bore size guides. I'm going to make kinda like reverse pilots. Here are the first three candidates. 94 Rem, Flues and an AJ Aubrey.

2 Piper. I too was surprised to learn of the Lefevre being a full length choke. I knew that my H grades / 2 1/2"s were indeed tapered full length but I thought it was a flukey thing. My bores above the cones are .747 and taper to the last 2" inches where they dive to IC an XF right and left repectively.

I do not want to argue with the experts; I am just an "amateur" gunsmith basically because I need to be my own gunsmith, but I never have a problem with an off-center cut opening a choke.
Perhaps just plain luck or, as you said, the chokes I opened have some parallel at the end of barrell (Winchester 101, Browning A-5, Ugartechea sxs, Remington 870 and some others I do not remember now).
What I noticed is that my 3 reamers (Expanding reamer made by Taylor and Jonnes, England) H6, H7 and H8 size, have some conical shape in the blades. If you measure them in the tip, you obtain about 0.005" less diameter than in the center or at the end. I think that this conical shape in the reamer helps to "autocenter" the blades and cut straight.
If you do this cutting by hand I can not see how you can cut off-center, because the reamer has the blades opposite to each other, so one blade can not cut if there is some "pressure" from opposite side.
I do not want to be a "hard head", but I still think an adjustable reamer is made to "autocenter" and made parallel cuts.

Anyway good luck with your shotgun´s choke opening proyect, you will enjoy to do it yourself and I am sure you will do in right!

Best,

What kind of comic was that in? If the ribs are loose then any work can loosen them further. I've bored hundreds of chokes and never had it happen.

Jose;
The two major types of choke constriction encountered are the conical/parallel & Taper. On the first type you have a cone section which reduces the dia of the bore which is followed by a short parallel section at the muzzle. On the later the entire choke section is a cone ending at the muzzle.
Imagine two bbls both having .729" (18.5mm) bores & choked to .690" (17.5mm), one having each type of choke. Then imagine inserting a solid rod which will just enter the choke to a depth equal to the length of the choke from the muzzle end. If you then tried to "Rock" that rod the one in the parallel choke would be un-movable, but the one in the taper choke could rock until it hit the angle of the choke wall, as it only has that one point of contact.
I can assure you that an adjustable reamer can do the same & will cut at what ever angle it happens to be started in this case. After the first few cuts create a parallel it will then tend to follow that parallel whether it happens to be in line with the bore or not. Those first few cuts however are totally dependent upon "EyeBall" alignment to the outside of the bbl, one can't see the bore while doing the reaming.
Of the guns you mention I know that some of them had & highly suspect they all had the conical parallel chokes, which would account for your positive results.
I do appreciate your input on this & hope my explanation clears up what I was saying. Successful operation of one of these adjustsble reamers for this task is dependant on taking only very light cuts & being very careful "Not" to apply any sideways pressure. If enough sideways pressure exists to hold the cutting edge into the meatal they can cut on one side only.

2 Piper:

Thank you for your explanation.

I just had good luck when I cut those chokes! No change for point of impact, but wider patterns that helps a lot to be a better shotgun shooter.

Best,

2 Piper: If I were to insert the adj reamer from the breech and as I insert it I place turned bore size 'pilots' at intervals, do you think that there would be enough support/guidance to keep the reamer centered in the bore/choke?

The PILOT BUSHINGS go on the REAMER not the reamer drive handle. You will need a smaller "pilot bushing" in the forward position on the reamer and a larger "pilot bushing" on the rear position of the reamer. For more details call me at 703-855-1110.

Good Shooting To You, Jent