Do you use a roughing reamer? Do you pre bore? Or do you do the whole chamber with a finish reamer?

Does it make a difference to you if you use a piloted reamer our no?


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No, No, Yes, and definitely YES!!!

I drill and taper bore to a bore that is indicated beforehand. Lack of a bushing would not bother me as my reamer is following the taper bored hole. Several ways to skin the cat.

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Several ways to skin the cat.

Yes Sir there sure are!

I mostly wonder why the pre-boring thing when using a piloted reamer? If you pre-bore it seems to me that there is nothing for the reamer to follow until the chamber is quite deep.....



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My indicator will reach the throat area of most chambers. If I indicate the throat area and taper bore to that point, That is my goal. I want the reamer to follow my taper bored hole that is indicated to the bore. Get the word"taper bored". I want my chamber to be concentric with the bore at the throat. If your bore runs out a little an your bushing follows it instead if my bored hole, I will probably have a slightly crooked chamber that is a little large at the base of the cartridge. This method is a little over kill for other than a precision competition barrel, but the little things help.
You might contact Gene Bukys in Crosby and see if he will show you his chambering method. Gene is a Hall of Fame shooter, won the last 2 World Championships, and is by and far the hottest BR shooter in the World the last 4-6 years.

The theory is that the reamer will follow the true hole; I have done it that way but it makes me nervous; I would rather have the pilot riding on rifling. You can alternate between the two methods so as to never cut deeper than your pilot can reach. I admit to drilling some clearance holes on big fat small bores to remove some meat....

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You might contact Gene Bukys in Crosby and see if he will show you his chambering method.

You know I really ought to do that. He is a member at our gun club and I have talked with him, he seems a very good sort.

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I will probably have a slightly crooked chamber that is a little large at the base of the cartridge.

I have had a couple of factory rifles with this problem. You can see and measure the enlarged base of the cartridge. Hard on case life.

Butch, I think I am following you with the taper bore. How much taper do you use and how do you arrive at the angle.

I only do my own work and am not limited by time to make a profit. If your reamer is in the tailstock, indicate your compound to follow your reamer. That will give you the proper angle. Below are my chambering tools.

I push my reamer and don't allow my tool to push it off to the side. A floating reamer holder ain't bad, but it does influence by a little the travel of the reamer.
I think I understand what I am doing from a machinist point of view.

Thanks for the follow up and pictures.

Yes! Very much so!


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With support from a bored start, a reamer can even correct a misaligned chamber; given enough setback (1/2 inch or more).
I rough with a drill bit about .015 to .020 under the diameter of the cartridge at the shoulder and drill to a depth which allows the pilot to engage.
BR and "F" class rifles, I bore to an indicated throat. Regards, Bill.