A Note on Chamber Reamers
To non-experienced amateur like me who has (with various degrees of success) tried to make various simple pieces on a lathe, a chamber reamer is a mysterious wonder of manufacturing. For about $100 you get a razor sharp form tool capable of cutting steel manufactured to something like 0.0002" dimensional tolerance.
Brands:
I've bought Clymer, Manson Precision, and JGS new. For cutting by hand, Clymer
and Manson reamers were great. The JGS reamers seemed not to cut as smoothly
but still cut a nice chamber. I've bought other reamers used with various
outcomes. Manson precision is apparently a small company, and if you email
them or call you will probably end up conversing with Dave Manson. Manson
Precision is also unique in that they will sharpen anybody's reamer for a
fairly nominal charge ($30 last time I checked).
Whatever the brand, it is important the reamer be sharp. If not, it will cut a rough chamber and it will be very hard to get it to cut by hand (as in finish chambering a Mauser barrel) at all.
Where to Get Them:
Before the internet, a chamber reamer represented a lifetime investment. (I
fully intend to hold on to my 223, 6mm and 308 reamers. However, I can't see
much further use for the 35 Whelen reamer I have and will most likely sell
it.) Now thanks to the internet there are three options for a hobbyist who
doesn't want to hold on to a reamer for a lifetime. These are buy new and
sell, buy used (eBay) and sell, and rent.
For common chamberings that are currently out of favor (like .270 Win or 25-06) you can't beat the prices you find on eBay. However, watch out for "I don't know anything about this.." or "It was my Dads..." disclaimers followed by "All sales are final." I bought a reamer that was mad dull like that. I'll be sending it off to Manson Precision for sharpening. The seller claimed to "not know anything", but the package had a "---------- Guns" business return address. Look for info like "Bought last month and cut one chamber..." or somebody willing to stand behind his sale.
For chamberings that are "in style", like any of the WSM or benchrest ones, they sell on eBay for only like 10% off retail. Better to buy new. Keep your sale documentation in order to document the reamer is fairly new and you will be able to sell it on eBay for almost what you paid for it. As far as where to buy new, I buy mine from Brownells, even though they are not the cheapest source. I have been buying from them for more than 25 years. They also have a technical support number you can call and talk to a real person who will try to answer your questions.
For an odd chambering that you won't see come up on ebay often, you should rent the reamer. Renting is not cheap but if you buy something like a 7mm Mauser reamer you won't be able to sell it for much. I rented reamers a couple of times from Shawnie Tool (www.reamerrentals.com) when they first got started. There was a couple of mix ups as far as what they sent that I attributed to them just getting started. However, whether it was inefficiency or they were just trying to make things right, they undercharged my credit card for the rentals, so I can't complain.