A question for those who have re-chambered.

[Potashminer]

I am probably getting in over my head, but I want to try re-chambering a barrel. I have read much Internet discussion about the pilot on a chambering reamer - pros and cons of solid versus live pilots. So, what happens when a chambering reamer pilot does not even get to the bore - I am thinking like the 308 Norma Mags that were created from 30-06 M1917 and Springfield 1903. Does a chambering reamer actually need a pilot? If someone can explain how such a job was done, I would appreciate hearing about it.

 

[guntech]

In chambering a .30 caliber magnum from a 30-06 the existing chamber will guide the reamer until a pilot will engage.

If the old chamber is not centered on the bore the new magnum chamber will not be either.

No pilot is required if you pre bore the chamber 10 thou under size and then use a reamer. The reamer will follow the boring. Of course the pre bore needs to be concentric with the bore.

 

[Potashminer]

Thank you, Guntech. That BSA barrel that WhyNot was playing with is on the way to me. Apparently, .270" bore and .282" groove. Currently chambered in 270 Win. Several comments to "simply" re-chamber to 280 Rem. My 280 Rem finishing reamer has a .275" solid pilot, so it is not likely to fit down that bore. I believe I understand how the reamer will create the slightly longer and wider body, neck and throat - the pilot issue has got me stumped... I do not have the tools or skill to re-grind that pilot to match that bore, so I am considering removing it completely, or getting it chewed down small enough that it would do no harm.

Of course, that sacrifices the reamer, since I doubt there are many other barrels like that, unless of course, there emerges a great run on creating a "wildcat" 270-280 Rem - I am sure one could gain 20 or 30 fps over the parent 270 chamber, but even then, the neck and throat would be oversize for a .277 bullet...

 

[fingers284]

I take it your reamer is a "solid pilot" model. Your described problem is the reason I only buy "live pilot" reamers, their a bit more money but a new "pilot" is easy to cut if you encounter a tight or loose bore.

You should be able to find a "tool maker" somewhere close that can precision grind your solid pilot to fit your barrel bore (will be a few bucks but a lot cheaper than buying a complete new reamer), but as you say "its only good for that barrel or another just like it".

 

[Potashminer]

So, if I was to buy a "live pilot" 280 reamer, I could install a .270-ish pilot bushing on it?? That is .005" smaller diameter than "normal" for a 280 Rem. If so, I assume I could also just make the jump to 280 AI, and do the same?

 

[guntech]

^
Yes.