Hello
For you gunsmiths, a question.

It may be redundant, but I cant find the thread.

Lets say you have a reamer that has a fixed pilot.
A customer wants you to run the reamer into an already-chambered barrel with a bore diameter larger than the pilot. To make a wildcat by changing the body and shoulder of the existing barrel's chambering, but leave the neck alone.

Can you do it? Is there some way to make a little bushing to adapt the pilot to the bore diameter?

Joe, even if you could make little bushing you'd still need a throater (reamer) to cut the throat for the new bore dia. Removable pilot reamers may allow for what you want to do, but you'll still need throater.

Biggest problem is the shoulder area of the reamer starts cutting before the pilot can reach the bore. If you are lucky it may work, but look for a non concentric chamber, maybe chatter, maybe a cooked throat.

But, I have done just this by reaming a 30-06 out to 300 Win Mag. Worked fine. Reamer cuts on the shoulder far before the pilot gets to the bore. And a good floating reamer holder helps.

Would not use this method for a match rifle, but, usually start with a new barrel and a match reamer designed for the purpose.

JoeM,

Of course the best way to do the job for a "paying customer" would be to have the correct tooling that would accept interchangeable "live" pilots to start.

However lacking these, then yes, it is possible to make a "slip on" bushing that will fit the bore. The quickest way to accomplish this would be to make an oversize bushing of heat treatable material, heat treat it then attach it to the existing pilot using either cement or a low temp, soft solder so as not to change the heat treating.

Place the reamer on centers and with a carbide cutter, turn it to within .001 of the desired diameter. Polish it the rest of the way making sure the edges are rounded and polished also, so as not to damage the bore.

For heat treating, take the bushing and stick it to a magnet and hold it over a bucket of cold water. Take a propane torch and slowly play the heat evenly, until it drops into the bucket of water. At this point it should be quite hard and brittle.

Clean off the scale and lightly polish it so you can watch the colors as you lightly reheat the piece. As you apply the heat, the first noticeable color seen will be yellow. When you see the yellow start to appear, quench it. That should be sufficient for this purpose.

Good luck,

Malm